subject:(Quantum information)

University of New Mexico

1. Norris, Leigh. Internal Spin Control, Squeezing and Decoherence in Ensembles of Alkali Atomic Spins.

Degree: Physics & Astronomy, 2015, University of New Mexico

URL: http://hdl.handle.net/1928/25808

► Large atomic ensembles interacting with light are one of the most promising platforms for quantum information processing. In the past decade, novel applications for these… (more)

▼ Large atomic ensembles interacting with light are one of the most promising platforms for quantum information processing. In the past decade, novel applications for these systems have emerged in quantum communication, quantum computing, and metrology. Essential to all of these applications is the controllability of the atomic ensemble, which is facilitated by a strong coupling between the atoms and light. Non-classical spin squeezed states are a crucial step in attaining greater ensemble control. The degree of entanglement present in these states, furthermore, serves as a benchmark for the strength of the atom-light interaction. Outside the broader context of quantum information processing with atomic ensembles, spin squeezed states have applications in metrology, where their quantum correlations can be harnessed to improve the precision of magnetometers and atomic clocks. This dissertation focuses upon the production of spin squeezed states in large ensembles of cold trapped alkali atoms interacting with optical fields. While most treatments of spin squeezing consider only the case in which the ensemble is composed of two level systems or qubits, we utilize the entire ground manifold of an alkali atom with hyperfine spin f greater or equal to 1/2, a qudit. Spin squeezing requires non-classical correlations between the constituent atomic spins, which are generated through the atoms' collective coupling to the light. Either through measurement or multiple interactions with the atoms, the light mediates an entangling interaction that produces quantum correlations. Because the spin squeezing treated in this dissertation ultimately originates from the coupling between the light and atoms, conventional approaches of improving this squeezing have focused on increasing the optical density of the ensemble. The greater number of internal degrees of freedom and the controllability of the spin-f ground hyperfine manifold enable novel methods of enhancing squeezing. In particular, we find that state preparation using control of the internal hyperfine spin increases the entangling power of squeezing protocols when f>1/2. Post-processing of the ensemble using additional internal spin control converts this entanglement into metrologically useful spin squeezing. By employing a variation of the Holstein-Primakoff approximation, in which the collective spin observables of the atomic ensemble are treated as quadratures of a bosonic mode, we model entanglement generation, spin squeezing and the effects of internal spin control. The Holstein-Primakoff formalism also enables us to take into account the decoherence of the ensemble due to optical pumping. While most works ignore or treat optical pumping phenomenologically, we employ a master equation derived from first principles. Our analysis shows that state preparation and the hyperfine spin size have a substantial impact upon both the generation of spin squeezing and the decoherence of the ensemble. Through a numerical search, we determine state preparations that enhance… Advisors/Committee Members: Deutsch, Ivan, Jessen, Poul, Miyake, Akimasa, Becerra, Elohim.

Subjects/Keywords: Quantum Information

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APA (6^th Edition):

Norris, L. (2015). Internal Spin Control, Squeezing and Decoherence in Ensembles of Alkali Atomic Spins. (Doctoral Dissertation). University of New Mexico. Retrieved from http://hdl.handle.net/1928/25808

Chicago Manual of Style (16^th Edition):

Norris, Leigh. “Internal Spin Control, Squeezing and Decoherence in Ensembles of Alkali Atomic Spins.” 2015. Doctoral Dissertation, University of New Mexico. Accessed February 22, 2020. http://hdl.handle.net/1928/25808.

MLA Handbook (7^th Edition):

Norris, Leigh. “Internal Spin Control, Squeezing and Decoherence in Ensembles of Alkali Atomic Spins.” 2015. Web. 22 Feb 2020.

Vancouver:

Norris L. Internal Spin Control, Squeezing and Decoherence in Ensembles of Alkali Atomic Spins. [Internet] [Doctoral dissertation]. University of New Mexico; 2015. [cited 2020 Feb 22]. Available from: http://hdl.handle.net/1928/25808.

Council of Science Editors:

Norris L. Internal Spin Control, Squeezing and Decoherence in Ensembles of Alkali Atomic Spins. [Doctoral Dissertation]. University of New Mexico; 2015. Available from: http://hdl.handle.net/1928/25808

University of Waterloo

2. McKague, Matthew. Quantum Information Processing with Adversarial Devices.

Degree: 2010, University of Waterloo

URL: http://hdl.handle.net/10012/5259

► We consider several applications in black-box quantum computation in which untrusted physical quantum devices are connected together to produce an experiment. By examining the outcome… (more)

▼ We consider several applications in black-box quantum computation in which untrusted physical quantum devices are connected together to produce an experiment. By examining the outcome statistics of such an experiment, and comparing them against the desired experiment, we may hope to certify that the physical experiment is implementing the desired experiment. This is useful in order to verify that a calculation has been performed correctly, that measurement outcomes are secure, or that the devices are producing the desired state. First, we introduce constructions for a family of simulations, which duplicate the outcome statistics of an experiment but are not exactly the same as the desired experiment. This places limitations on how strict we may be with the requirements we place on the physical devices. We identify many simulations, and consider their implications for quantum foundations as well as security related applications. The most general application of black-box quantum computing is self-testing circuits, in which a generic physical circuit may be tested against a given circuit. Earlier results were restricted to circuits described on a real Hilbert space. We give new proofs for earlier results and begin work extending them to circuits on a complex Hilbert space with a test that verifies complex measurements. For security applications of black-box quantum computing, we consider device independent quantum key distribution (DIQKD). We may consider DIQKD as an extension of QKD (quantum key distribution) in which the model of the physical measurement devices is replaced with an adversarial model. This introduces many technical problems, such as unbounded dimension, but promises increased security since the many complexities hidden by traditional models are implicitly considered. We extend earlier work by proving security with fewer assumptions. Finally, we consider the case of black-box state characterization. Here the emphasis is placed on providing robust results with operationally meaningful measures. The goal is to certify that a black box device is producing high quality maximally entangled pairs of qubits using only untrusted measurements and a single statistic, the CHSH value, defined using correlations of outcomes from the two parts of the system. We present several measures of quality and prove bounds for them.

Subjects/Keywords: quantum information

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APA (6^th Edition):

McKague, M. (2010). Quantum Information Processing with Adversarial Devices. (Thesis). University of Waterloo. Retrieved from http://hdl.handle.net/10012/5259

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

Chicago Manual of Style (16^th Edition):

McKague, Matthew. “Quantum Information Processing with Adversarial Devices.” 2010. Thesis, University of Waterloo. Accessed February 22, 2020. http://hdl.handle.net/10012/5259.

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

MLA Handbook (7^th Edition):

McKague, Matthew. “Quantum Information Processing with Adversarial Devices.” 2010. Web. 22 Feb 2020.

Vancouver:

McKague M. Quantum Information Processing with Adversarial Devices. [Internet] [Thesis]. University of Waterloo; 2010. [cited 2020 Feb 22]. Available from: http://hdl.handle.net/10012/5259.

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

Council of Science Editors:

McKague M. Quantum Information Processing with Adversarial Devices. [Thesis]. University of Waterloo; 2010. Available from: http://hdl.handle.net/10012/5259

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

University of Illinois – Urbana-Champaign

3. Christensen, Bradley G. Advanced tests of nonlocality with entangled photons.

Degree: PhD, Physics, 2016, University of Illinois – Urbana-Champaign

URL: http://hdl.handle.net/2142/90538

► In 1935, Einstein, Podolsky, and Rosen questioned whether quantum mechanics can be complete, as it seemingly does not adhere to a natural view of reality:… (more)

▼ In 1935, Einstein, Podolsky, and Rosen questioned whether quantum mechanics can be complete, as it seemingly does not adhere to a natural view of reality: local realism, which is the notion that an event can only be influenced by events in the past lightcone, and can only influence events in the future lightcone. This question sparked a philosophical debate that lasted for three decades, until John Bell demonstrated that not only are quantum mechanics and local realism philosophically incompatible, but they predict different statistical results for an appropriate set of measurements on entangled particles, which changed the debate to a scientific discussion. Since then, Bell inequality violations have occurred in a plethora of systems, hinting that local realism is indeed wrong. However, every experiment had imperfections that complicated the interpretation – the experiments had so-called "loopholes" which allowed local realism to persist. In this manuscript, we present our work in using optimized sources of entangled photons to perform the long-sought loophole-free Bell test. This landmark experiment invalidates local realism to the best that science will allow. Beyond answering questions on reality, these Bell tests have a important application in generating provably-secure private random numbers, which then can be used as a seed for cryptographic applications. Not only do we demonstrate that nonlocality must exist, but we begin an experimental exploration in an attempt to understand and quantify this nonlocality. We do so by considering all theories that obey no-signaling (or relativistic causality). In our experiments, we observe the counter-intuitive feature of measuring more nonlocality with less entangled states. We also place a bound on the predictive power of any theory that obeys relativistic causality. And finally, we are able to measure quantum correlations only attainable through complex qubits. This work merely begins to probe the quantum boundary, beginning a journey that may someday find evidence of a beyond-quantum theory. Advisors/Committee Members: Kwiat, Paul G (advisor), Eckstein, James (Committee Chair), Leggett, Anthony (committee member), Mason, Nadya (committee member).

Subjects/Keywords: Quantum nonlocality; Quantum information

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APA (6^th Edition):

Christensen, B. G. (2016). Advanced tests of nonlocality with entangled photons. (Doctoral Dissertation). University of Illinois – Urbana-Champaign. Retrieved from http://hdl.handle.net/2142/90538

Chicago Manual of Style (16^th Edition):

Christensen, Bradley G. “Advanced tests of nonlocality with entangled photons.” 2016. Doctoral Dissertation, University of Illinois – Urbana-Champaign. Accessed February 22, 2020. http://hdl.handle.net/2142/90538.

MLA Handbook (7^th Edition):

Christensen, Bradley G. “Advanced tests of nonlocality with entangled photons.” 2016. Web. 22 Feb 2020.

Vancouver:

Christensen BG. Advanced tests of nonlocality with entangled photons. [Internet] [Doctoral dissertation]. University of Illinois – Urbana-Champaign; 2016. [cited 2020 Feb 22]. Available from: http://hdl.handle.net/2142/90538.

Council of Science Editors:

Christensen BG. Advanced tests of nonlocality with entangled photons. [Doctoral Dissertation]. University of Illinois – Urbana-Champaign; 2016. Available from: http://hdl.handle.net/2142/90538

Louisiana State University

4. Roy Bardhan, Bhaskar. Topics in Quantum Metrology, Control, and Communications.

Degree: PhD, Physical Sciences and Mathematics, 2014, Louisiana State University

URL: etd-10052014-073714 ; https://digitalcommons.lsu.edu/gradschool_dissertations/3752

► Noise present in an environment has significant impacts on a quantum system affecting properties like coherence, entanglement and other metrological features of a quantum state.… (more)

▼ Noise present in an environment has significant impacts on a quantum system affecting properties like coherence, entanglement and other metrological features of a quantum state. In this dissertation, we address the effects of different types of noise that are present in a communication channel (or medium) and an interferometric setup, and analyze their effects in the contexts of preserving coherence and entanglement, phase sensitivity, and limits on rate of communication through noisy channels. We first consider quantum optical phase estimation in quantum metrology when phase fluctuations are introduced in the system by its interaction with a noisy environment. By considering path-entangled dual-mode photon Fock states in a Mach-Zehnder optical interferometric configuration, we show that such phase fluctuations affect phase sensitivity and visibility by adding noise to the phase to be estimated. We also demonstrate that the optimal detection strategy for estimating a phase in the presence of such phase noise is provided by the parity detection scheme. We then investigate the random birefringent noise present in an optical fiber affecting the coherence properties of a single photon polarization qubit propagating through it. We show that a simple but effective control technique, called dynamical decoupling, can be used to suppress the effects of the dephasing noise, thereby preserving its ability to carry the encoded quantum information in a long-distance optical fiber communication system. Optical amplifiers and attenuators can also add noise to an entangled quantum system, deteriorating the non-classical properties of the state. We show this by considering a two-mode squeezed vacuum state, which is a Gaussian entangled state, propagating through a noisy medium, and characterizing the loss of entanglement in the covariance matrix and the symplectic formalism for this state. Finally, we discuss limits on the rate of communication in the context of sending messages through noisy optical quantum communication channels. In particular, we prove that a strong converse theorem holds under a maximum photon number constraint for these channels, guaranteeing that the success probability in decoding the message vanishes in the asymptotic limit for the rate exceeding the capacity of the channels.

Subjects/Keywords: Quantum optics; Quantum information theory

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APA · Chicago · MLA · Vancouver · CSE | Export to Zotero / EndNote / Reference Manager

APA (6^th Edition):

Roy Bardhan, B. (2014). Topics in Quantum Metrology, Control, and Communications. (Doctoral Dissertation). Louisiana State University. Retrieved from etd-10052014-073714 ; https://digitalcommons.lsu.edu/gradschool_dissertations/3752

Chicago Manual of Style (16^th Edition):

Roy Bardhan, Bhaskar. “Topics in Quantum Metrology, Control, and Communications.” 2014. Doctoral Dissertation, Louisiana State University. Accessed February 22, 2020. etd-10052014-073714 ; https://digitalcommons.lsu.edu/gradschool_dissertations/3752.

MLA Handbook (7^th Edition):

Roy Bardhan, Bhaskar. “Topics in Quantum Metrology, Control, and Communications.” 2014. Web. 22 Feb 2020.

Vancouver:

Roy Bardhan B. Topics in Quantum Metrology, Control, and Communications. [Internet] [Doctoral dissertation]. Louisiana State University; 2014. [cited 2020 Feb 22]. Available from: etd-10052014-073714 ; https://digitalcommons.lsu.edu/gradschool_dissertations/3752.

Council of Science Editors:

Roy Bardhan B. Topics in Quantum Metrology, Control, and Communications. [Doctoral Dissertation]. Louisiana State University; 2014. Available from: etd-10052014-073714 ; https://digitalcommons.lsu.edu/gradschool_dissertations/3752

5. Pitalúa-García, Damián. Quantum information, Bell inequalities and the no-signalling principle.

Degree: PhD, 2014, University of Cambridge

URL: https://www.repository.cam.ac.uk/handle/1810/245205 ; http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.600535

► This PhD thesis contains a general introduction and three main chapters. Chapter 2 investigates Bell inequalities that generalize the CHSH and Braunstein-Caves inequalities. Chapter 3… (more)

▼ This PhD thesis contains a general introduction and three main chapters. Chapter 2 investigates Bell inequalities that generalize the CHSH and Braunstein-Caves inequalities. Chapter 3 shows a derivation of an upper bound on the success probability of a class of quantum teleportation protocols, denoted as port-based teleportation, from the no-cloning theorem and the no-signalling principle. Chapter 4 introduces the principle of quantum information causality. Chapter 2 considers the predictions of quantum theory and local hidden variable theories (LHVT) for the correlations obtained by measuring a pair of qubits by projections defined by randomly chosen axes separated by a given angle θ. The predictions of LHVT correspond to binary colourings of the Bloch sphere with antipodal points oppositely coloured. We show a Bell inequality for all θ, which generalizes the CHSH and the Braunstein-Caves inequalities in the sense that the measurement choices are not restricted to be in a finite set, but are constrained only by the angle θ. We motivate and explore the hypothesis that for a continuous range of θ > 0, the maximum correlation (anticorrelation) is obtained by assigning to one qubit the colouring with one hemisphere black and the other white, and assigning the same (reverse) colouring to the other qubit. We describe numerical tests that are consistent with this hypothesis and bound the range of θ. Chapter 3 shows a derivation of an upper bound on the success probability of port-based teleportation from the no-cloning theorem and the no-signalling principle. Chapter 4 introduces the principle of quantum information causality, a quantum version of the information causality principle. The quantum information causality principle states the maximum amount of quantum information that a transmitted quantum system can communicate as a function of its dimension, independently of any quantum physical resources previously shared by the communicating parties. These principles reduce to the no-signalling principle if no systems are transmitted. We present a new quantum information task, the quantum information causality game, whose success probability is upper bounded by the new principle, and show that an optimal strategy to perform it combines the quantum teleportation and superdense coding protocols with a task that has classical inputs.

Subjects/Keywords: 530.12; Quantum information; Quantum foundations

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APA · Chicago · MLA · Vancouver · CSE | Export to Zotero / EndNote / Reference Manager

APA (6^th Edition):

Pitalúa-García, D. (2014). Quantum information, Bell inequalities and the no-signalling principle. (Doctoral Dissertation). University of Cambridge. Retrieved from https://www.repository.cam.ac.uk/handle/1810/245205 ; http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.600535

Chicago Manual of Style (16^th Edition):

Pitalúa-García, Damián. “Quantum information, Bell inequalities and the no-signalling principle.” 2014. Doctoral Dissertation, University of Cambridge. Accessed February 22, 2020. https://www.repository.cam.ac.uk/handle/1810/245205 ; http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.600535.

MLA Handbook (7^th Edition):

Pitalúa-García, Damián. “Quantum information, Bell inequalities and the no-signalling principle.” 2014. Web. 22 Feb 2020.

Vancouver:

Pitalúa-García D. Quantum information, Bell inequalities and the no-signalling principle. [Internet] [Doctoral dissertation]. University of Cambridge; 2014. [cited 2020 Feb 22]. Available from: https://www.repository.cam.ac.uk/handle/1810/245205 ; http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.600535.

Council of Science Editors:

Pitalúa-García D. Quantum information, Bell inequalities and the no-signalling principle. [Doctoral Dissertation]. University of Cambridge; 2014. Available from: https://www.repository.cam.ac.uk/handle/1810/245205 ; http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.600535

6. Pitalúa-García, Damián. Quantum information, Bell inequalities and the no-signalling principle.

Degree: PhD, 2014, University of Cambridge

URL: https://www.repository.cam.ac.uk/handle/1810/245205https://www.repository.cam.ac.uk/bitstream/1810/245205/2/license.txt ; https://www.repository.cam.ac.uk/bitstream/1810/245205/3/Finalthesis.pdf.txt ; https://www.repository.cam.ac.uk/bitstream/1810/245205/4/Finalthesis.pdf.jpg

► This PhD thesis contains a general introduction and three main chapters. Chapter 2 investigates Bell inequalities that generalize the CHSH and Braunstein-Caves inequalities. Chapter 3… (more)

▼ This PhD thesis contains a general introduction and three main chapters. Chapter 2 investigates Bell inequalities that generalize the CHSH and Braunstein-Caves inequalities. Chapter 3 shows a derivation of an upper bound on the success probability of a class of quantum teleportation protocols, denoted as port-based teleportation, from the no-cloning theorem and the no-signalling principle. Chapter 4 introduces the principle of quantum information causality. Chapter 2 considers the predictions of quantum theory and local hidden variable theories (LHVT) for the correlations obtained by measuring a pair of qubits by projections defined by randomly chosen axes separated by a given angle θ. The predictions of LHVT correspond to binary colourings of the Bloch sphere with antipodal points oppositely coloured. We show a Bell inequality for all θ, which generalizes the CHSH and the Braunstein-Caves inequalities in the sense that the measurement choices are not restricted to be in a finite set, but are constrained only by the angle θ. We motivate and explore the hypothesis that for a continuous range of θ > 0, the maximum correlation (anticorrelation) is obtained by assigning to one qubit the colouring with one hemisphere black and the other white, and assigning the same (reverse) colouring to the other qubit. We describe numerical tests that are consistent with this hypothesis and bound the range of θ. Chapter 3 shows a derivation of an upper bound on the success probability of port-based teleportation from the no-cloning theorem and the no-signalling principle. Chapter 4 introduces the principle of quantum information causality, a quantum version of the information causality principle. The quantum information causality principle states the maximum amount of quantum information that a transmitted quantum system can communicate as a function of its dimension, independently of any quantum physical resources previously shared by the communicating parties. These principles reduce to the no-signalling principle if no systems are transmitted. We present a new quantum information task, the quantum information causality game, whose success probability is upper bounded by the new principle, and show that an optimal strategy to perform it combines the quantum teleportation and superdense coding protocols with a task that has classical inputs.

Subjects/Keywords: Quantum information; Quantum foundations

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APA (6^th Edition):

Pitalúa-García, D. (2014). Quantum information, Bell inequalities and the no-signalling principle. (Doctoral Dissertation). University of Cambridge. Retrieved from https://www.repository.cam.ac.uk/handle/1810/245205https://www.repository.cam.ac.uk/bitstream/1810/245205/2/license.txt ; https://www.repository.cam.ac.uk/bitstream/1810/245205/3/Finalthesis.pdf.txt ; https://www.repository.cam.ac.uk/bitstream/1810/245205/4/Finalthesis.pdf.jpg

Chicago Manual of Style (16^th Edition):

Pitalúa-García, Damián. “Quantum information, Bell inequalities and the no-signalling principle.” 2014. Doctoral Dissertation, University of Cambridge. Accessed February 22, 2020. https://www.repository.cam.ac.uk/handle/1810/245205https://www.repository.cam.ac.uk/bitstream/1810/245205/2/license.txt ; https://www.repository.cam.ac.uk/bitstream/1810/245205/3/Finalthesis.pdf.txt ; https://www.repository.cam.ac.uk/bitstream/1810/245205/4/Finalthesis.pdf.jpg.

MLA Handbook (7^th Edition):

Pitalúa-García, Damián. “Quantum information, Bell inequalities and the no-signalling principle.” 2014. Web. 22 Feb 2020.

Vancouver:

Pitalúa-García D. Quantum information, Bell inequalities and the no-signalling principle. [Internet] [Doctoral dissertation]. University of Cambridge; 2014. [cited 2020 Feb 22]. Available from: https://www.repository.cam.ac.uk/handle/1810/245205https://www.repository.cam.ac.uk/bitstream/1810/245205/2/license.txt ; https://www.repository.cam.ac.uk/bitstream/1810/245205/3/Finalthesis.pdf.txt ; https://www.repository.cam.ac.uk/bitstream/1810/245205/4/Finalthesis.pdf.jpg.

Council of Science Editors:

Pitalúa-García D. Quantum information, Bell inequalities and the no-signalling principle. [Doctoral Dissertation]. University of Cambridge; 2014. Available from: https://www.repository.cam.ac.uk/handle/1810/245205https://www.repository.cam.ac.uk/bitstream/1810/245205/2/license.txt ; https://www.repository.cam.ac.uk/bitstream/1810/245205/3/Finalthesis.pdf.txt ; https://www.repository.cam.ac.uk/bitstream/1810/245205/4/Finalthesis.pdf.jpg

University of Waterloo

7. Khatri, Sumeet. Symmetric Extendability of Quantum States and the Extreme Limits of Quantum Key Distribution.

Degree: 2016, University of Waterloo

URL: http://hdl.handle.net/10012/10993

► We investigate QKD protocols with two-way classical post-processing that are based on the well-known six-state and BB84 signal states. In these QKD protocols, the source… (more)

▼ We investigate QKD protocols with two-way classical post-processing that are based on the well-known six-state and BB84 signal states. In these QKD protocols, the source (Alice) sends quantum signals to the receiver (Bob), who measures them, leaving only classical data on both sides. Our goal is to find the highest value of the quantum bit-error rate (QBER) Q for which two-way classical post-processing protocols on the data can distill secret keys. Using the BB84 signal states, such protocols currently exist for Q<\frac{1}{5}. On the other hand, for Q ≥ \frac{1}{4} no such protocol can exist as the observed data is compatible with an intercept-resend attack. This leaves the interesting question of whether successful two-way protocols exist in the interval \frac{1}{5} ≤ Q<\frac{1}{4}. For the six-state signal states, the corresponding interval is known to be \frac{5-√{5}}{10} ≤ Q<\frac{1}{3}. We search for two-way protocols because it turns out that within these intervals Alice and Bob's correlations are symmetrically extendable, meaning that Bob and the eavesdropper (Eve) are completely indistinguishable from Alice's point of view, making any one-way Alice-to-Bob post-processing protocol insecure. A two-way protocol might be able to break the symmetry between Bob and Eve, and it must do so in order to distill a secret key because any two-way protocol will necessarily terminate with a one-way communication step, at which point the symmetric extendability of Alice and Bob's updated correlations must be checked again. We first show that the search for two-way protocols breaking the symmetric extendability of Alice and Bob's correlations can be restricted to a search over post-selection protocols if all we care about is whether secret key can at all be distilled and not about the rate of distillation. We then provide strong analytical and numerical evidence to suggest that no two-way classical post-processing protocol exists within the gap when the six-state signal states are used. Under quantum entanglement distillation protocols, it is known that secret key can be distilled right up to the intercept-resend bounds of \frac{1}{4} and \frac{1}{3} for the BB84 and six-state signal states, respectively. We therefore want to know whether classical post-processing protocols are just as good at distilling secret keys as quantum ones. Our results appear to indicate that they are not.

Subjects/Keywords: Quantum information; Quantum cryptography

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APA (6^th Edition):

Khatri, S. (2016). Symmetric Extendability of Quantum States and the Extreme Limits of Quantum Key Distribution. (Thesis). University of Waterloo. Retrieved from http://hdl.handle.net/10012/10993

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

Chicago Manual of Style (16^th Edition):

Khatri, Sumeet. “Symmetric Extendability of Quantum States and the Extreme Limits of Quantum Key Distribution.” 2016. Thesis, University of Waterloo. Accessed February 22, 2020. http://hdl.handle.net/10012/10993.

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

MLA Handbook (7^th Edition):

Khatri, Sumeet. “Symmetric Extendability of Quantum States and the Extreme Limits of Quantum Key Distribution.” 2016. Web. 22 Feb 2020.

Vancouver:

Khatri S. Symmetric Extendability of Quantum States and the Extreme Limits of Quantum Key Distribution. [Internet] [Thesis]. University of Waterloo; 2016. [cited 2020 Feb 22]. Available from: http://hdl.handle.net/10012/10993.

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

Council of Science Editors:

Khatri S. Symmetric Extendability of Quantum States and the Extreme Limits of Quantum Key Distribution. [Thesis]. University of Waterloo; 2016. Available from: http://hdl.handle.net/10012/10993

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

University of Waterloo

8. Magesan, Easwar. Characterizing Noise in Quantum Systems.

Degree: 2012, University of Waterloo

URL: http://hdl.handle.net/10012/6832

► In practice, quantum systems are not completely isolated from their environment and the resulting system-environment interaction can lead to information leakage from the system. As… (more)

Subjects/Keywords: Quantum; Noise; Quantum information; Randomization

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APA · Chicago · MLA · Vancouver · CSE | Export to Zotero / EndNote / Reference Manager

APA (6^th Edition):

Magesan, E. (2012). Characterizing Noise in Quantum Systems. (Thesis). University of Waterloo. Retrieved from http://hdl.handle.net/10012/6832

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

Chicago Manual of Style (16^th Edition):

Magesan, Easwar. “Characterizing Noise in Quantum Systems.” 2012. Thesis, University of Waterloo. Accessed February 22, 2020. http://hdl.handle.net/10012/6832.

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

MLA Handbook (7^th Edition):

Magesan, Easwar. “Characterizing Noise in Quantum Systems.” 2012. Web. 22 Feb 2020.

Vancouver:

Magesan E. Characterizing Noise in Quantum Systems. [Internet] [Thesis]. University of Waterloo; 2012. [cited 2020 Feb 22]. Available from: http://hdl.handle.net/10012/6832.

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

Council of Science Editors:

Magesan E. Characterizing Noise in Quantum Systems. [Thesis]. University of Waterloo; 2012. Available from: http://hdl.handle.net/10012/6832

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

University of Waterloo

9. Govia, Luke Colin Gene. Theory and Applications of Josephson Photomultipliers.

Degree: 2012, University of Waterloo

URL: http://hdl.handle.net/10012/6971

► This thesis describes the back action of microwave-photon detection via a Josephson photomultiplier (JPM), a superconducting qubit coupled strongly to a high-quality mi- crowave cavity,… (more)

Subjects/Keywords: Quantum Information; Quantum Computing

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APA (6^th Edition):

Govia, L. C. G. (2012). Theory and Applications of Josephson Photomultipliers. (Thesis). University of Waterloo. Retrieved from http://hdl.handle.net/10012/6971

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

Chicago Manual of Style (16^th Edition):

Govia, Luke Colin Gene. “Theory and Applications of Josephson Photomultipliers.” 2012. Thesis, University of Waterloo. Accessed February 22, 2020. http://hdl.handle.net/10012/6971.

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

MLA Handbook (7^th Edition):

Govia, Luke Colin Gene. “Theory and Applications of Josephson Photomultipliers.” 2012. Web. 22 Feb 2020.

Vancouver:

Govia LCG. Theory and Applications of Josephson Photomultipliers. [Internet] [Thesis]. University of Waterloo; 2012. [cited 2020 Feb 22]. Available from: http://hdl.handle.net/10012/6971.

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

Council of Science Editors:

Govia LCG. Theory and Applications of Josephson Photomultipliers. [Thesis]. University of Waterloo; 2012. Available from: http://hdl.handle.net/10012/6971

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

University of Waterloo

10. Fisher, Kent. Implementing quantum gates and channels using linear optics.

Degree: 2012, University of Waterloo

URL: http://hdl.handle.net/10012/7067

► This thesis deals with the implementation of quantum channels using linear optics. We begin with overviews of some important concepts in both quantum information and… (more)

Subjects/Keywords: quantum information; quantum optics

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APA (6^th Edition):

Fisher, K. (2012). Implementing quantum gates and channels using linear optics. (Thesis). University of Waterloo. Retrieved from http://hdl.handle.net/10012/7067

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

Chicago Manual of Style (16^th Edition):

Fisher, Kent. “Implementing quantum gates and channels using linear optics.” 2012. Thesis, University of Waterloo. Accessed February 22, 2020. http://hdl.handle.net/10012/7067.

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

MLA Handbook (7^th Edition):

Fisher, Kent. “Implementing quantum gates and channels using linear optics.” 2012. Web. 22 Feb 2020.

Vancouver:

Fisher K. Implementing quantum gates and channels using linear optics. [Internet] [Thesis]. University of Waterloo; 2012. [cited 2020 Feb 22]. Available from: http://hdl.handle.net/10012/7067.

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

Council of Science Editors:

Fisher K. Implementing quantum gates and channels using linear optics. [Thesis]. University of Waterloo; 2012. Available from: http://hdl.handle.net/10012/7067

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

University of Cambridge

11. Adlam, Emily Christine. Relativistic quantum tasks.

Degree: PhD, 2017, University of Cambridge

URL: https://www.repository.cam.ac.uk/handle/1810/274930 ; https://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.745041

► Quantum mechanics, which describes the behaviour of matter and energy on very small scales, is one of the most successful theories in the history of… (more)

Subjects/Keywords: Quantum information; Quantum cryptography; Quantum foundations

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APA · Chicago · MLA · Vancouver · CSE | Export to Zotero / EndNote / Reference Manager

APA (6^th Edition):

Adlam, E. C. (2017). Relativistic quantum tasks. (Doctoral Dissertation). University of Cambridge. Retrieved from https://www.repository.cam.ac.uk/handle/1810/274930 ; https://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.745041

Chicago Manual of Style (16^th Edition):

Adlam, Emily Christine. “Relativistic quantum tasks.” 2017. Doctoral Dissertation, University of Cambridge. Accessed February 22, 2020. https://www.repository.cam.ac.uk/handle/1810/274930 ; https://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.745041.

MLA Handbook (7^th Edition):

Adlam, Emily Christine. “Relativistic quantum tasks.” 2017. Web. 22 Feb 2020.

Vancouver:

Adlam EC. Relativistic quantum tasks. [Internet] [Doctoral dissertation]. University of Cambridge; 2017. [cited 2020 Feb 22]. Available from: https://www.repository.cam.ac.uk/handle/1810/274930 ; https://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.745041.

Council of Science Editors:

Adlam EC. Relativistic quantum tasks. [Doctoral Dissertation]. University of Cambridge; 2017. Available from: https://www.repository.cam.ac.uk/handle/1810/274930 ; https://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.745041

Wesleyan University

12. Kan, Angus. Quantum Computing: Temperature Scaling of Decoherence.

Degree: Physics, 2018, Wesleyan University

URL: https://wesscholar.wesleyan.edu/etd_mas_theses/193

► After years of effort by quantum scientists, decoherence due to thermal effects still remains a huge hindrance to the upscaling of quantum computers. This… (more)

Subjects/Keywords: Quantum; Quantum Computing; Quantum Information; Decoherence

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APA · Chicago · MLA · Vancouver · CSE | Export to Zotero / EndNote / Reference Manager

APA (6^th Edition):

Kan, A. (2018). Quantum Computing: Temperature Scaling of Decoherence. (Masters Thesis). Wesleyan University. Retrieved from https://wesscholar.wesleyan.edu/etd_mas_theses/193

Chicago Manual of Style (16^th Edition):

Kan, Angus. “Quantum Computing: Temperature Scaling of Decoherence.” 2018. Masters Thesis, Wesleyan University. Accessed February 22, 2020. https://wesscholar.wesleyan.edu/etd_mas_theses/193.

MLA Handbook (7^th Edition):

Kan, Angus. “Quantum Computing: Temperature Scaling of Decoherence.” 2018. Web. 22 Feb 2020.

Vancouver:

Kan A. Quantum Computing: Temperature Scaling of Decoherence. [Internet] [Masters thesis]. Wesleyan University; 2018. [cited 2020 Feb 22]. Available from: https://wesscholar.wesleyan.edu/etd_mas_theses/193.

Council of Science Editors:

Kan A. Quantum Computing: Temperature Scaling of Decoherence. [Masters Thesis]. Wesleyan University; 2018. Available from: https://wesscholar.wesleyan.edu/etd_mas_theses/193

University of Waterloo

13. Meyer-Scott, Evan. Heralding Photonic Qubits for Quantum Communication.

Degree: 2016, University of Waterloo

URL: http://hdl.handle.net/10012/10201

► Quantum communication attempts to harness the unique rules of quantum mechanics to perform communication tasks that are difficult or impossible using classical rules. To realize… (more)

▼ Quantum communication attempts to harness the unique rules of quantum mechanics to perform communication tasks that are difficult or impossible using classical rules. To realize these benefits, information must be carried on quantum systems. Photons make excellent carriers because they interact very little with the environment, move quickly, and can naturally store quantum information in their polarization. However, it is notoriously difficult to detect a single photon without destroying it. Standard detectors simply absorb the photon, losing the quantum information. This is a critical outstanding problem in quantum communication, as advanced protocols need to know exactly when a photon has arrived at a receiver after transmission through the atmosphere or an optical fibre before performing further quantum-information-processing tasks. Certifying a photon’s presence is of particular interest in tests of Bell’s inequalities, which have only recently been performed without loopholes arising from photon loss, and in device-independent quantum cryptography, which relies on such Bell tests for security. In this thesis, I first present work on directly reducing losses in a successful loophole-free Bell test. This is an extremely difficult task that cannot be extended for long-distance communication. Therefore I then focus on ways to circumvent loss by detecting photons without destroying them while preserving their quantum information. First I analyze theoretically a way to herald photons using only linear-optical elements (beam splitters and phase shifters) and extra ancilla photons. Similar but older methods have been demonstrated experimentally by other groups, and my improvements will help future advanced quantum communication protocols. The main experiment in this thesis certifies the presence of a photon in a rather simple way: split the photon into two using a nonlinear optical crystal, then detect one of the pair to herald the other. I show in this first proof-of-principle experiment that photonic qubit precertification indeed preserves qubit states, with up to (92.3 ± 0.6)% fidelity and rates of 1100 events per hour. With reductions in detector dark counts, precertification could outperform direct transmission, even with extremely lossy fibre links. Finally, I present two sources of photons based on nonlinearities in optical fibres. One of the limitations of the photon splitting scheme for heralding is the low success probability due to the very low likelihood of splitting a photon in two. In these fibre photon sources I investigate increasing the splitting likelihood in four-wave mixing through advanced materials and fibre designs. I use polarization-maintaining fibres to generate entangled photon pairs as a prerequisite to precertification, with (92.2 ± 0.2)% fidelity to a maximally-entangled state. Then I show that one type of highly nonlinear chalcogenide glass, never before used for photon pair generation, could outperform standard nonlinear crystals by two orders of magnitude, with calculated…

Subjects/Keywords: quantum optics; quantum information; quantum communication; photonics

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APA (6^th Edition):

Meyer-Scott, E. (2016). Heralding Photonic Qubits for Quantum Communication. (Thesis). University of Waterloo. Retrieved from http://hdl.handle.net/10012/10201

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

Chicago Manual of Style (16^th Edition):

Meyer-Scott, Evan. “Heralding Photonic Qubits for Quantum Communication.” 2016. Thesis, University of Waterloo. Accessed February 22, 2020. http://hdl.handle.net/10012/10201.

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

MLA Handbook (7^th Edition):

Meyer-Scott, Evan. “Heralding Photonic Qubits for Quantum Communication.” 2016. Web. 22 Feb 2020.

Vancouver:

Meyer-Scott E. Heralding Photonic Qubits for Quantum Communication. [Internet] [Thesis]. University of Waterloo; 2016. [cited 2020 Feb 22]. Available from: http://hdl.handle.net/10012/10201.

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

Council of Science Editors:

Meyer-Scott E. Heralding Photonic Qubits for Quantum Communication. [Thesis]. University of Waterloo; 2016. Available from: http://hdl.handle.net/10012/10201

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

University of Waterloo

14. Qassemi Maloomeh, Farzad. Nanoscale quantum transport for quantum information processing.

Degree: 2013, University of Waterloo

URL: http://hdl.handle.net/10012/7451

► In this thesis, I study quantum transport of electron (e.g., current and noise) in quantum dots exploring microscopic processes responsible for spin-relaxation in double quantum… (more)

Subjects/Keywords: Quantum Information; Spintronics

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APA (6^th Edition):

Qassemi Maloomeh, F. (2013). Nanoscale quantum transport for quantum information processing. (Thesis). University of Waterloo. Retrieved from http://hdl.handle.net/10012/7451

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

Chicago Manual of Style (16^th Edition):

Qassemi Maloomeh, Farzad. “Nanoscale quantum transport for quantum information processing.” 2013. Thesis, University of Waterloo. Accessed February 22, 2020. http://hdl.handle.net/10012/7451.

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

MLA Handbook (7^th Edition):

Qassemi Maloomeh, Farzad. “Nanoscale quantum transport for quantum information processing.” 2013. Web. 22 Feb 2020.

Vancouver:

Qassemi Maloomeh F. Nanoscale quantum transport for quantum information processing. [Internet] [Thesis]. University of Waterloo; 2013. [cited 2020 Feb 22]. Available from: http://hdl.handle.net/10012/7451.

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

Council of Science Editors:

Qassemi Maloomeh F. Nanoscale quantum transport for quantum information processing. [Thesis]. University of Waterloo; 2013. Available from: http://hdl.handle.net/10012/7451

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

ETH Zürich

15. Arnon-Friedman, Rotem. Reductions to IID in Device-independent Quantum Information Processing.

Degree: 2018, ETH Zürich

URL: http://hdl.handle.net/20.500.11850/298420

► The field of device-independent quantum information processing concerns itself with devising and analysing protocols, such as quantum key distribution and quantum tomography, without referring to… (more)

▼ The field of device-independent quantum information processing concerns itself with devising and analysing protocols, such as quantum key distribution and quantum tomography, without referring to the quality of the physical devices utilised to execute the protocols. Instead, the analysis is based on the observed correlations that arise during a repeated interaction with the devices and, in particular, their ability to violate the so called Bell inequalities. Since the analysis of device-independent protocols holds irrespectively of the underlying physical device, it implies that any device can be used to execute the protocols: If the apparatus is of poor quality, the users of the protocol will detect it and abort; otherwise, they will accomplish their goal. This strong statement comes at a price — the analysis of device-independent protocols is, a priori, extremely challenging. Having good techniques at hand is thus crucial. The thesis presents an approach that can be taken to simplify the analysis of device-independent information processing protocols. The idea is the following: Instead of analysing the most general device leading to the observed correlations, one should first analyse a significantly simpler device that, in each interaction with the user, behaves in an identical way, independently of all other interactions. We call such a device an independently and identically distributed (IID) device. As the next step, special techniques are used to prove that, without loss of generality, the analysis of the IID device implies similar results for the most general device. Such techniques reduce the problem of analysing the general scenario to that of analysing an IID one and, hence, we term them reductions to IID. We present two mathematical techniques that can be used as reductions to IID in the device-independent setting: de Finetti reductions for correlations and the entropy accumulation theorem. Each technique is accompanied by a showcase-application that exemplifies the reduction’s usage and benefits. Specifically, we use our de Finetti reduction to prove a non-signalling (super-quantum) parallel repetition theorem, belonging to a family of theorems discussed in theoretical computer science. The entropy accumulation theorem is used to prove the security of device-independent quantum cryptographic protocols. Performing the analysis via a reduction to IID instead of directly analysing the most general scenarios leads to simpler proofs and significant quantitive improvements, matching the tight results proven when analysing IID devices. In particular, our analysis of device-independent quantum key distribution protocols produces essentially optimal key rates and noise tolerance, crucial for all future experimental implementations of device-independent cryptography. Advisors/Committee Members: Renner, Renato, Gisin, Nicolas, Raz, Ran, Winter, Andreas.

Subjects/Keywords: QUANTUM INFORMATION (INFORMATION THEORY)

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APA · Chicago · MLA · Vancouver · CSE | Export to Zotero / EndNote / Reference Manager

APA (6^th Edition):

Arnon-Friedman, R. (2018). Reductions to IID in Device-independent Quantum Information Processing. (Doctoral Dissertation). ETH Zürich. Retrieved from http://hdl.handle.net/20.500.11850/298420

Chicago Manual of Style (16^th Edition):

Arnon-Friedman, Rotem. “Reductions to IID in Device-independent Quantum Information Processing.” 2018. Doctoral Dissertation, ETH Zürich. Accessed February 22, 2020. http://hdl.handle.net/20.500.11850/298420.

MLA Handbook (7^th Edition):

Arnon-Friedman, Rotem. “Reductions to IID in Device-independent Quantum Information Processing.” 2018. Web. 22 Feb 2020.

Vancouver:

Arnon-Friedman R. Reductions to IID in Device-independent Quantum Information Processing. [Internet] [Doctoral dissertation]. ETH Zürich; 2018. [cited 2020 Feb 22]. Available from: http://hdl.handle.net/20.500.11850/298420.

Council of Science Editors:

Arnon-Friedman R. Reductions to IID in Device-independent Quantum Information Processing. [Doctoral Dissertation]. ETH Zürich; 2018. Available from: http://hdl.handle.net/20.500.11850/298420

16. O'Malley, Peter James Joyce. Superconducting Qubits: Dephasing and Quantum Chemistry.

Degree: 2016, University of California – eScholarship, University of California

URL: http://www.escholarship.org/uc/item/21x6x9tk

► One of the most exciting potential applications of a quantum computer is the abilityto efficiently simulate quantum systems, a task that is out of the… (more)

Subjects/Keywords: Quantum physics; Physics; Chemistry; Quantum Algorithms; Quantum Chemistry; Quantum Computation; Quantum Information; Quantum Noise

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APA (6^th Edition):

O'Malley, P. J. J. (2016). Superconducting Qubits: Dephasing and Quantum Chemistry. (Thesis). University of California – eScholarship, University of California. Retrieved from http://www.escholarship.org/uc/item/21x6x9tk

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

Chicago Manual of Style (16^th Edition):

O'Malley, Peter James Joyce. “Superconducting Qubits: Dephasing and Quantum Chemistry.” 2016. Thesis, University of California – eScholarship, University of California. Accessed February 22, 2020. http://www.escholarship.org/uc/item/21x6x9tk.

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

MLA Handbook (7^th Edition):

O'Malley, Peter James Joyce. “Superconducting Qubits: Dephasing and Quantum Chemistry.” 2016. Web. 22 Feb 2020.

Vancouver:

O'Malley PJJ. Superconducting Qubits: Dephasing and Quantum Chemistry. [Internet] [Thesis]. University of California – eScholarship, University of California; 2016. [cited 2020 Feb 22]. Available from: http://www.escholarship.org/uc/item/21x6x9tk.

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

Council of Science Editors:

O'Malley PJJ. Superconducting Qubits: Dephasing and Quantum Chemistry. [Thesis]. University of California – eScholarship, University of California; 2016. Available from: http://www.escholarship.org/uc/item/21x6x9tk

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

17. Croal, Callum. Quantum correlations in continuous variable mixed states : from discord to signatures .

Degree: 2016, University of St. Andrews

URL: http://hdl.handle.net/10023/8969

► This thesis studies continuous variable mixed states with the aim of better understanding the fundamental behaviour of quantum correlations in such states, as well as… (more)

▼ This thesis studies continuous variable mixed states with the aim of better understanding the fundamental behaviour of quantum correlations in such states, as well as searching for applications of these correlations. I first investigate the interesting phenomenon of discord increase under local loss and explain the behaviour by considering the non-orthogonality of quantum states. I then explore the counter-intuitive result where entanglement can be created by a passive optical beamsplitter, even if the input states are classical, as long as the input states are part of a larger globally nonclassical system. This result emphasises the importance of global correlations in a quantum state, and I propose an application of this protocol in the form of quantum dense coding. Finally, I develop a quantum digital signature protocol that can be described entirely using the continuous variable formalism. Quantum digital signatures provide a method to ensure the integrity and provenance of a message using quantum states. They follow a similar method to quantum key distribution (QKD), but require less post-processing, which means they can sometimes be implemented over channels that are inappropriate for QKD. The method I propose uses homodyne measurement to verify the signature, unlike previous protocols that use single photon detection. The single photon detection of previous methods is designed to give unambiguous results about the signature, but this comes at the cost of getting no information much of the time. Using homodyne detection has the advantage of giving results all the time, but this means that measurement results always have some ambiguity. I show that, even with this ambiguity, the signature protocol based on homodyne measurement outperforms previous protocols, with the advantage enhanced when technical considerations are included. Therefore this represents an interesting new direction in the search for a practical quantum digital signature scheme. Advisors/Committee Members: Korolkova, Natalia (advisor).

Subjects/Keywords: Quantum information; Quantum digital signatures; Quantum discord; Quantum optics

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APA (6^th Edition):

Croal, C. (2016). Quantum correlations in continuous variable mixed states : from discord to signatures . (Thesis). University of St. Andrews. Retrieved from http://hdl.handle.net/10023/8969

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

Chicago Manual of Style (16^th Edition):

Croal, Callum. “Quantum correlations in continuous variable mixed states : from discord to signatures .” 2016. Thesis, University of St. Andrews. Accessed February 22, 2020. http://hdl.handle.net/10023/8969.

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

MLA Handbook (7^th Edition):

Croal, Callum. “Quantum correlations in continuous variable mixed states : from discord to signatures .” 2016. Web. 22 Feb 2020.

Vancouver:

Croal C. Quantum correlations in continuous variable mixed states : from discord to signatures . [Internet] [Thesis]. University of St. Andrews; 2016. [cited 2020 Feb 22]. Available from: http://hdl.handle.net/10023/8969.

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

Council of Science Editors:

Croal C. Quantum correlations in continuous variable mixed states : from discord to signatures . [Thesis]. University of St. Andrews; 2016. Available from: http://hdl.handle.net/10023/8969

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

18. Stockill, Robert Hugh James. Linking confined electron spins through coherent light-matter interaction.

Degree: PhD, 2017, University of Cambridge

URL: https://www.repository.cam.ac.uk/handle/1810/297360

► Electron spins confined to self-assembled quantum dots are considered as nodes for a coherent optical network capable of supporting distributed quantum states. Through a series… (more)

▼ Electron spins confined to self-assembled quantum dots are considered as nodes for a coherent optical network capable of supporting distributed quantum states. Through a series of experiments, the work contributing to this dissertation examines some of the key criteria for constructing such a network. First, the ability to optically extract a coherent spin state from the quantum dot without perturbing the nuclear environment is explored: nuclear feedback is an issue that has frustrated previous studies into electron spin coherence in these systems. With the novel techniques we develop, we identify and characterise the previously undetermined intrinsic mechanisms that govern the coherence of the central spin. We show how the coherence of the electron spin is intimately related to the growth of these strained nanostructures. Second, a model network is constructed in which two spins confined to separate quantum dots are projected into a highly entangled state. This is the first time electron spins in distant quantum dots have been entangled, and in doing so we demonstrate controllable entanglement generation at the highest rates recorded for optically accessible qubit definitions. We investigate the realisation of a hybrid quantum network by demonstrating the first interconnect between wholly different single quantum systems: a semiconductor quantum dot and a trapped ytterbium ion. In forming an optical link between these two complementary qubit definitions, we show that we can circumvent their intrinsic optical differences through coherent photon generation at the quantum dot. A network built from these diverse constituents could combine the ultrafast operations self-assembled quantum dots enable with the long coherence times states in trapped ions experience. Finally, in a step towards truly scalable entanglement generation between quantum dot spins, we design minimally invasive structures that will funnel large proportions of the optical dipole field from the optically dense material that surrounds the quantum dot. The techniques developed in this work and the knowledge gained from their operation should enable the demonstration the creation of high-order nonlocal states between quantum dot spins, single photons and trapped ions, as well as the development of new optically active systems that will benefit from enhanced spin coherence.

Subjects/Keywords: Quantum Optics; Quantum Dots; Quantum Entanglement; Quantum Information; Spins

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APA (6^th Edition):

Stockill, R. H. J. (2017). Linking confined electron spins through coherent light-matter interaction. (Doctoral Dissertation). University of Cambridge. Retrieved from https://www.repository.cam.ac.uk/handle/1810/297360

Chicago Manual of Style (16^th Edition):

Stockill, Robert Hugh James. “Linking confined electron spins through coherent light-matter interaction.” 2017. Doctoral Dissertation, University of Cambridge. Accessed February 22, 2020. https://www.repository.cam.ac.uk/handle/1810/297360.

MLA Handbook (7^th Edition):

Stockill, Robert Hugh James. “Linking confined electron spins through coherent light-matter interaction.” 2017. Web. 22 Feb 2020.

Vancouver:

Stockill RHJ. Linking confined electron spins through coherent light-matter interaction. [Internet] [Doctoral dissertation]. University of Cambridge; 2017. [cited 2020 Feb 22]. Available from: https://www.repository.cam.ac.uk/handle/1810/297360.

Council of Science Editors:

Stockill RHJ. Linking confined electron spins through coherent light-matter interaction. [Doctoral Dissertation]. University of Cambridge; 2017. Available from: https://www.repository.cam.ac.uk/handle/1810/297360

Boston University

19. Fitzpatrick, Casey Alan. High-dimensional quantum information processing with linear optics.

Degree: PhD, Electrical & Computer Engineering, 2017, Boston University

URL: http://hdl.handle.net/2144/23564

► Quantum information processing (QIP) is an interdisciplinary field concerned with the development of computers and information processing systems that utilize quantum mechanical properties of nature… (more)

▼ Quantum information processing (QIP) is an interdisciplinary field concerned with the development of computers and information processing systems that utilize quantum mechanical properties of nature to carry out their function. QIP systems have become vastly more practical since the turn of the century. Today, QIP applications span imaging, cryptographic security, computation, and simulation (quantum systems that mimic other quantum systems). Many important strategies improve quantum versions of classical information system hardware, such as single photon detectors and quantum repeaters. Another more abstract strategy engineers high-dimensional quantum state spaces, so that each successful event carries more information than traditional two-level systems allow. Photonic states in particular bring the added advantages of weak environmental coupling and data transmission near the speed of light, allowing for simpler control and lower system design complexity. In this dissertation, numerous novel, scalable designs for practical high-dimensional linear-optical QIP systems are presented. First, a correlated photon imaging scheme using orbital angular momentum (OAM) states to detect rotational symmetries in objects using measurements, as well as building images out of those interactions is reported. Then, a statistical detection method using chains of OAM superpositions distributed according to the Fibonacci sequence is established and expanded upon. It is shown that the approach gives rise to schemes for sorting, detecting, and generating the recursively defined high-dimensional states on which some quantum cryptographic protocols depend. Finally, an ongoing study based on a generalization of the standard optical multiport for applications in quantum computation and simulation is reported upon. The architecture allows photons to reverse momentum inside the device. This in turn enables realistic implementation of controllable linear-optical scattering vertices for carrying out quantum walks on arbitrary graph structures, a powerful tool for any quantum computer. It is shown that the novel architecture provides new, efficient capabilities for the optical quantum simulation of Hamiltonians and topologically protected states. Further, these simulations use exponentially fewer resources than feedforward techniques, scale linearly to higher-dimensional systems, and use only linear optics, thus offering a concrete experimentally achievable implementation of graphical models of discrete-time quantum systems.

Subjects/Keywords: Quantum physics; Optics; Photonics; Quantum computing; Quantum information processing; Quantum optics

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APA (6^th Edition):

Fitzpatrick, C. A. (2017). High-dimensional quantum information processing with linear optics. (Doctoral Dissertation). Boston University. Retrieved from http://hdl.handle.net/2144/23564

Chicago Manual of Style (16^th Edition):

Fitzpatrick, Casey Alan. “High-dimensional quantum information processing with linear optics.” 2017. Doctoral Dissertation, Boston University. Accessed February 22, 2020. http://hdl.handle.net/2144/23564.

MLA Handbook (7^th Edition):

Fitzpatrick, Casey Alan. “High-dimensional quantum information processing with linear optics.” 2017. Web. 22 Feb 2020.

Vancouver:

Fitzpatrick CA. High-dimensional quantum information processing with linear optics. [Internet] [Doctoral dissertation]. Boston University; 2017. [cited 2020 Feb 22]. Available from: http://hdl.handle.net/2144/23564.

Council of Science Editors:

Fitzpatrick CA. High-dimensional quantum information processing with linear optics. [Doctoral Dissertation]. Boston University; 2017. Available from: http://hdl.handle.net/2144/23564

University of Waterloo

20. Killoran, Nathan. Entanglement quantification and quantum benchmarking of optical communication devices.

Degree: 2012, University of Waterloo

URL: http://hdl.handle.net/10012/6662

► In this thesis, we develop a number of operational tests and tools for benchmarking the quantum nature of optical quantum communication devices. Using the laws… (more)

Subjects/Keywords: quantum communication; quantum optics; quantum benchmarks; quantum information; entanglement

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APA (6^th Edition):

Killoran, N. (2012). Entanglement quantification and quantum benchmarking of optical communication devices. (Thesis). University of Waterloo. Retrieved from http://hdl.handle.net/10012/6662

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

Chicago Manual of Style (16^th Edition):

Killoran, Nathan. “Entanglement quantification and quantum benchmarking of optical communication devices.” 2012. Thesis, University of Waterloo. Accessed February 22, 2020. http://hdl.handle.net/10012/6662.

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

MLA Handbook (7^th Edition):

Killoran, Nathan. “Entanglement quantification and quantum benchmarking of optical communication devices.” 2012. Web. 22 Feb 2020.

Vancouver:

Killoran N. Entanglement quantification and quantum benchmarking of optical communication devices. [Internet] [Thesis]. University of Waterloo; 2012. [cited 2020 Feb 22]. Available from: http://hdl.handle.net/10012/6662.

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

Council of Science Editors:

Killoran N. Entanglement quantification and quantum benchmarking of optical communication devices. [Thesis]. University of Waterloo; 2012. Available from: http://hdl.handle.net/10012/6662

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

21. Fisher, Kent. Photons & Phonons: A room-temperature diamond quantum memory.

Degree: 2016, University of Waterloo

URL: http://hdl.handle.net/10012/10663

► This thesis presents demonstrations of the storage and manipulation of single photons in a room-temperature diamond quantum memory using a Raman memory protocol. We report… (more)

▼ This thesis presents demonstrations of the storage and manipulation of single photons in a room-temperature diamond quantum memory using a Raman memory protocol. We report on results from four experiments. In the first we demonstrate single photon storage and, upon retrieval, verify the quantum nature of the light with a Hanbury Brown Twiss measurement of g^(2)(0) = 0.65±0.07. A measurement of g^(2)(0) < 1 is indicative of quantum light. This is the first demonstration of single photon storage where the bandwidth of the stored light is greater than 1 THz. The diamond memory stores light for over 13 times the duration of the input wavepacket. In the second experiment, we report the storage and retrieval of polarization-encoded qubits and demonstrate qubit storage above a classical bound. We also verify that entanglement between the input photon and an auxiliary persists through storage and retrieval. We then turn to additional uses of a Raman quantum memory. We demonstrate that a photon stored in the diamond memory can, upon retrieval, have its frequency and bandwidth converted. We report frequency conversion over a range of 4.2 times the bandwidth of the input photon (4.1 nm, 2.3 THz), and bandwidth modulation between 0.5 to 1.9 times the bandwidth of the input. We verify that the output light from storage and spectral manipulation is still non-classical in nature. Finally, we demonstrate both single- and two-photon quantum interference mediated by the diamond memory, where the memory acts as a beamsplitter between photon and optical phonon modes in the diamond lattice. In a first experiment, a single photon is split into two time-bins. The first time-bin is stored in the memory, then recalled and made to interfere with the second time-bin producing fringes. In a second experiment, a photon from a weak coherent state is stored in the memory and, upon retrieval, undergoes Hong- Ou-Mandel interference with a second photon. We measure Hong-Ou-Mandel interference with a visibility of 59% giving a signature of non-classical interference (> 50%). This collection of experiments establishes the diamond memory as a prime candidate for certain quantum communication and processing applications. These results demonstrate the potential for the diamond memory to be an integrated platform for photon storage, spectral conversion, and information processing.

Subjects/Keywords: Quantum optics; Quantum information; Quantum memory; Quantum computing

11 more images…

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APA (6^th Edition):

Fisher, K. (2016). Photons & Phonons: A room-temperature diamond quantum memory. (Thesis). University of Waterloo. Retrieved from http://hdl.handle.net/10012/10663

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

Chicago Manual of Style (16^th Edition):

Fisher, Kent. “Photons & Phonons: A room-temperature diamond quantum memory.” 2016. Thesis, University of Waterloo. Accessed February 22, 2020. http://hdl.handle.net/10012/10663.

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

MLA Handbook (7^th Edition):

Fisher, Kent. “Photons & Phonons: A room-temperature diamond quantum memory.” 2016. Web. 22 Feb 2020.

Vancouver:

Fisher K. Photons & Phonons: A room-temperature diamond quantum memory. [Internet] [Thesis]. University of Waterloo; 2016. [cited 2020 Feb 22]. Available from: http://hdl.handle.net/10012/10663.

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

Council of Science Editors:

Fisher K. Photons & Phonons: A room-temperature diamond quantum memory. [Thesis]. University of Waterloo; 2016. Available from: http://hdl.handle.net/10012/10663

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

University of Waterloo

22. Ma, Xian. Exploring the foundation of quantum information in quantum optics.

Degree: 2016, University of Waterloo

URL: http://hdl.handle.net/10012/10885

► Quantum information is promising in solving certain computational problems and information security. The power of its speed up and privacy is based on one of… (more)

Subjects/Keywords: Quantum information; Quantum foundation; Quantum optics; Envariance; Quantum state tomography

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APA · Chicago · MLA · Vancouver · CSE | Export to Zotero / EndNote / Reference Manager

APA (6^th Edition):

Ma, X. (2016). Exploring the foundation of quantum information in quantum optics. (Thesis). University of Waterloo. Retrieved from http://hdl.handle.net/10012/10885

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

Chicago Manual of Style (16^th Edition):

Ma, Xian. “Exploring the foundation of quantum information in quantum optics.” 2016. Thesis, University of Waterloo. Accessed February 22, 2020. http://hdl.handle.net/10012/10885.

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

MLA Handbook (7^th Edition):

Ma, Xian. “Exploring the foundation of quantum information in quantum optics.” 2016. Web. 22 Feb 2020.

Vancouver:

Ma X. Exploring the foundation of quantum information in quantum optics. [Internet] [Thesis]. University of Waterloo; 2016. [cited 2020 Feb 22]. Available from: http://hdl.handle.net/10012/10885.

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

Council of Science Editors:

Ma X. Exploring the foundation of quantum information in quantum optics. [Thesis]. University of Waterloo; 2016. Available from: http://hdl.handle.net/10012/10885

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

University of Waterloo

23. Meyer-Scott, Evan. Experimental quantum communication in demanding regimes.

Degree: 2011, University of Waterloo

URL: http://hdl.handle.net/10012/6052

► Quantum communication promises to outperform its classical counterparts and enable protocols previously impossible. Specifically, quantum key distribution (QKD) allows a cryptographic key to be shared… (more)

Subjects/Keywords: quantum communication; quantum information; quantum key distribution; QKD; quantum cryptography

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APA (6^th Edition):

Meyer-Scott, E. (2011). Experimental quantum communication in demanding regimes. (Thesis). University of Waterloo. Retrieved from http://hdl.handle.net/10012/6052

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

Chicago Manual of Style (16^th Edition):

Meyer-Scott, Evan. “Experimental quantum communication in demanding regimes.” 2011. Thesis, University of Waterloo. Accessed February 22, 2020. http://hdl.handle.net/10012/6052.

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

MLA Handbook (7^th Edition):

Meyer-Scott, Evan. “Experimental quantum communication in demanding regimes.” 2011. Web. 22 Feb 2020.

Vancouver:

Meyer-Scott E. Experimental quantum communication in demanding regimes. [Internet] [Thesis]. University of Waterloo; 2011. [cited 2020 Feb 22]. Available from: http://hdl.handle.net/10012/6052.

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

Council of Science Editors:

Meyer-Scott E. Experimental quantum communication in demanding regimes. [Thesis]. University of Waterloo; 2011. Available from: http://hdl.handle.net/10012/6052

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

University of Waterloo

24. Hincks, Ian. Exploring Practical Methodologies for the Characterization and Control of Small Quantum Systems.

Degree: 2018, University of Waterloo

URL: http://hdl.handle.net/10012/13711

► We explore methodologies for characterizing and controlling small quantum systems. We are interested in starting with a description of a quantum system, designing estimators for… (more)

Subjects/Keywords: quantum; quantum control; quantum information; bayesian inference; benchmarking; quantum characterization; inference

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APA · Chicago · MLA · Vancouver · CSE | Export to Zotero / EndNote / Reference Manager

APA (6^th Edition):

Hincks, I. (2018). Exploring Practical Methodologies for the Characterization and Control of Small Quantum Systems. (Thesis). University of Waterloo. Retrieved from http://hdl.handle.net/10012/13711

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

Chicago Manual of Style (16^th Edition):

Hincks, Ian. “Exploring Practical Methodologies for the Characterization and Control of Small Quantum Systems.” 2018. Thesis, University of Waterloo. Accessed February 22, 2020. http://hdl.handle.net/10012/13711.

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

MLA Handbook (7^th Edition):

Hincks, Ian. “Exploring Practical Methodologies for the Characterization and Control of Small Quantum Systems.” 2018. Web. 22 Feb 2020.

Vancouver:

Hincks I. Exploring Practical Methodologies for the Characterization and Control of Small Quantum Systems. [Internet] [Thesis]. University of Waterloo; 2018. [cited 2020 Feb 22]. Available from: http://hdl.handle.net/10012/13711.

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

Council of Science Editors:

Hincks I. Exploring Practical Methodologies for the Characterization and Control of Small Quantum Systems. [Thesis]. University of Waterloo; 2018. Available from: http://hdl.handle.net/10012/13711

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

University of Waterloo

25. Chamberland, Christopher. New methods in quantum error correction and fault-tolerant quantum computing.

Degree: 2018, University of Waterloo

URL: http://hdl.handle.net/10012/14049

► Quantum computers have the potential to solve several interesting problems in polynomial time for which no polynomial time classical algorithms have been found. However, one… (more)

▼ Quantum computers have the potential to solve several interesting problems in polynomial time for which no polynomial time classical algorithms have been found. However, one of the major challenges in building quantum devices is that quantum systems are very sensitive to noise arising from undesired interactions with the environment. Noise can lead to errors which can corrupt the results of the computation. Quantum error correction is one way to mitigate the effects of noise arising in quantum devices. With a plethora of quantum error correcting codes that can be used in various settings, one of the main challenges of quantum error correction is understanding how well various codes perform under more realistic noise models that can be observed in experiments. This thesis proposes a new decoding algorithm which can optimize threshold values of error correcting codes under different noise models. The algorithm can be applied to any Markovian noise model. Further, it is shown that for certain noise models, logical Clifford corrections can further improve a code's threshold value if the code obeys certain symmetries. Since gates and measurements cannot in general be performed with perfect precision, the operations required to perform quantum error correction can introduce more errors into the system thus negating the benefits of error correction. Fault-tolerant quantum computing is a way to perform quantum error correction with imperfect operations while retaining the ability to suppress errors as long as the noise is below a code's threshold. One of the main challenges in performing fault-tolerant error correction is the high resource requirements that are needed to obtain very low logical noise rates. With the use of flag qubits, this thesis develops new fault-tolerant error correction protocols that are applicable to arbitrary distance codes. Various code families are shown to satisfy the requirements of flag fault-tolerant error correction. We also provide circuits using a constant number of qubits for these codes. It is shown that the proposed flag fault-tolerant method uses fewer qubits than previous fault-tolerant error correction protocols. It is often the case that the noise afflicting a quantum device cannot be fully characterized. Further, even with some knowledge of the noise, it can be very challenging to use analytic decoding methods to improve the performance of a fault-tolerant scheme. This thesis presents decoding schemes using several state of the art machine learning techniques with a focus on fault-tolerant quantum error correction in regimes that are relevant to near term experiments. It is shown that even in low noise rate regimes and with no knowledge of the noise, noise can be further suppressed for small distance codes. Limitations of machine learning decoders as well as the classical resources required to perform active error correction are discussed. In many cases, gate times can be much shorter than typical measurement times of quantum states.…

Subjects/Keywords: Quantum error correction; Quantum computing; Fault-tolerant quantum computing; Quantum information

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APA (6^th Edition):

Chamberland, C. (2018). New methods in quantum error correction and fault-tolerant quantum computing. (Thesis). University of Waterloo. Retrieved from http://hdl.handle.net/10012/14049

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

Chicago Manual of Style (16^th Edition):

Chamberland, Christopher. “New methods in quantum error correction and fault-tolerant quantum computing.” 2018. Thesis, University of Waterloo. Accessed February 22, 2020. http://hdl.handle.net/10012/14049.

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

MLA Handbook (7^th Edition):

Chamberland, Christopher. “New methods in quantum error correction and fault-tolerant quantum computing.” 2018. Web. 22 Feb 2020.

Vancouver:

Chamberland C. New methods in quantum error correction and fault-tolerant quantum computing. [Internet] [Thesis]. University of Waterloo; 2018. [cited 2020 Feb 22]. Available from: http://hdl.handle.net/10012/14049.

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

Council of Science Editors:

Chamberland C. New methods in quantum error correction and fault-tolerant quantum computing. [Thesis]. University of Waterloo; 2018. Available from: http://hdl.handle.net/10012/14049

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

University of Cambridge

26. Stockill, Robert Hugh James. Linking confined electron spins through coherent light-matter interaction.

Degree: PhD, 2017, University of Cambridge

URL: https://www.repository.cam.ac.uk/handle/1810/297360 ; https://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.787757

► Electron spins confined to self-assembled quantum dots are considered as nodes for a coherent optical network capable of supporting distributed quantum states. Through a series… (more)

▼ Electron spins confined to self-assembled quantum dots are considered as nodes for a coherent optical network capable of supporting distributed quantum states. Through a series of experiments, the work contributing to this dissertation examines some of the key criteria for constructing such a network. First, the ability to optically extract a coherent spin state from the quantum dot without perturbing the nuclear environment is explored: nuclear feedback is an issue that has frustrated previous studies into electron spin coherence in these systems. With the novel techniques we develop, we identify and characterise the previously undetermined intrinsic mechanisms that govern the coherence of the central spin. We show how the coherence of the electron spin is intimately related to the growth of these strained nanostructures. Second, a model network is constructed in which two spins confined to separate quantum dots are projected into a highly entangled state. This is the first time electron spins in distant quantum dots have been entangled, and in doing so we demonstrate controllable entanglement generation at the highest rates recorded for optically accessible qubit definitions. We investigate the realisation of a hybrid quantum network by demonstrating the first interconnect between wholly different single quantum systems: a semiconductor quantum dot and a trapped ytterbium ion. In forming an optical link between these two complementary qubit definitions, we show that we can circumvent their intrinsic optical differences through coherent photon generation at the quantum dot. A network built from these diverse constituents could combine the ultrafast operations self-assembled quantum dots enable with the long coherence times states in trapped ions experience. Finally, in a step towards truly scalable entanglement generation between quantum dot spins, we design minimally invasive structures that will funnel large proportions of the optical dipole field from the optically dense material that surrounds the quantum dot. The techniques developed in this work and the knowledge gained from their operation should enable the demonstration the creation of high-order nonlocal states between quantum dot spins, single photons and trapped ions, as well as the development of new optically active systems that will benefit from enhanced spin coherence.

Subjects/Keywords: Quantum Optics; Quantum Dots; Quantum Entanglement; Quantum Information; Spins

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APA (6^th Edition):

Stockill, R. H. J. (2017). Linking confined electron spins through coherent light-matter interaction. (Doctoral Dissertation). University of Cambridge. Retrieved from https://www.repository.cam.ac.uk/handle/1810/297360 ; https://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.787757

Chicago Manual of Style (16^th Edition):

Stockill, Robert Hugh James. “Linking confined electron spins through coherent light-matter interaction.” 2017. Doctoral Dissertation, University of Cambridge. Accessed February 22, 2020. https://www.repository.cam.ac.uk/handle/1810/297360 ; https://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.787757.

MLA Handbook (7^th Edition):

Stockill, Robert Hugh James. “Linking confined electron spins through coherent light-matter interaction.” 2017. Web. 22 Feb 2020.

Vancouver:

Stockill RHJ. Linking confined electron spins through coherent light-matter interaction. [Internet] [Doctoral dissertation]. University of Cambridge; 2017. [cited 2020 Feb 22]. Available from: https://www.repository.cam.ac.uk/handle/1810/297360 ; https://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.787757.

Council of Science Editors:

Stockill RHJ. Linking confined electron spins through coherent light-matter interaction. [Doctoral Dissertation]. University of Cambridge; 2017. Available from: https://www.repository.cam.ac.uk/handle/1810/297360 ; https://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.787757

ETH Zürich

27. Stupar, Sandra. Operational approach to time and clocks in quantum theory.

Degree: 2018, ETH Zürich

URL: http://hdl.handle.net/20.500.11850/327503

► Throughout the existence of humankind, people have organised their lives based on the sunrise and sunset, the Moon phases and star movements. Nature has guided… (more)

▼ Throughout the existence of humankind, people have organised their lives based on the sunrise and sunset, the Moon phases and star movements. Nature has guided our daily routines, as it still does, and it would be hard to imagine what life would look like without the already known cycles imposed by nature. As the humanity progressed, we have realised that a day is not always of the same length, but our sleep cycle most often is, and that it would be extremely useful to have further references for organising our day and habits. So people started calculating time with the Sun clock, sand clock, water clock etc. Since these were all limited in their performance, mechanical and pendulum clocks were introduced later, followed by quartz clocks, and as the ultimate performing ones, in the 20th century the first atomic clocks were constructed. This revolutionised time-keeping, speeded up technology development and made very precise coordination in every-day lives possible. It is now hard to think of spending a day without an accurate watch. But where does this notion of time and clocks physically arise from? And is it valid only in the classical limit that we experience, or is it possible to introduce very precise and well-synchronised quantum clocks as well? This is what we will try to deal with in this thesis. We start from the assumption that the only observable time is the one given by clocks, and hence to learn more about quantum time we need to build good quantum clocks and try to synchronise them. We define clocks as quantum systems that need to provide a time reference, such as a sequence of ticks. Further, we attempt to find limits on their synchronisation, since it is well known that quantum systems interact with their environment thereby getting disturbed. What we find out is that the performance of the quantum clocks we define depends crucially on their dimension (number of the distinguishable states available), and that the quantum clocks of a certain dimension could possibly perform better than the classical ones with the same state space size. The limitations to synchronising local quantum clocks suggest that global time in quantum mechanics might not be a physically grounded notion. We also investigate what limitations would be imposed on the evolution of our Universe, if it itself was/contained a quantum clock providing ticks that we observe as time. Our results show that the theory of inflation is consistent with the time keeping the Universe needed to perform at its early beginning, while the speed of evolution as of today would not be fast enough for the Universe to be able to store its ticks then. Although our argument is still not completely general, and does not exclude other possible theories for the evolution of the Universe, it is a novel approach to combining cosmology with quantum information and it would be very interesting to extend this research further. Advisors/Committee Members: Renner, Renato, Short, Tony, Vedral, Vlatko.

Subjects/Keywords: PHYSICS; QUANTENINFORMATION (INFORMATIONSTHEORIE); Quantum information; Quantum information; QUANTUM THEORY

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APA · Chicago · MLA · Vancouver · CSE | Export to Zotero / EndNote / Reference Manager

APA (6^th Edition):

Stupar, S. (2018). Operational approach to time and clocks in quantum theory. (Doctoral Dissertation). ETH Zürich. Retrieved from http://hdl.handle.net/20.500.11850/327503

Chicago Manual of Style (16^th Edition):

Stupar, Sandra. “Operational approach to time and clocks in quantum theory.” 2018. Doctoral Dissertation, ETH Zürich. Accessed February 22, 2020. http://hdl.handle.net/20.500.11850/327503.

MLA Handbook (7^th Edition):

Stupar, Sandra. “Operational approach to time and clocks in quantum theory.” 2018. Web. 22 Feb 2020.

Vancouver:

Stupar S. Operational approach to time and clocks in quantum theory. [Internet] [Doctoral dissertation]. ETH Zürich; 2018. [cited 2020 Feb 22]. Available from: http://hdl.handle.net/20.500.11850/327503.

Council of Science Editors:

Stupar S. Operational approach to time and clocks in quantum theory. [Doctoral Dissertation]. ETH Zürich; 2018. Available from: http://hdl.handle.net/20.500.11850/327503

University of Waterloo

28. Jonsson, Robert H. Decoupling of Information Propagation from Energy Propagation.

Degree: 2016, University of Waterloo

URL: http://hdl.handle.net/10012/10770

► Information and energy are concepts central to our understanding of nature. Their relevance, in physics, ranges from fundamental physics, e.g., in black hole physics, all… (more)

▼ Information and energy are concepts central to our understanding of nature. Their relevance, in physics, ranges from fundamental physics, e.g., in black hole physics, all the way to future quantum computing technology. This thesis investigates how information and energy propagate in quantum fields. The main result is that in massless fields the propagation of information can decouple from the propagation of energy partially and, under special circumstances, even completely. It has been known that in general curved spacetimes, and also in odd-dimensional Minkowski space, signals can propagate slower than light even in a massless field. Here it is shown that the energy-to-information ratio of these classical timelike signals can approach zero. The extreme case is marked by two-dimensional Minkowski space. In this case, timelike signals reach arbitrarily far into the future lightcone, without diluting, and they carry no energy at all. Instead, the energy cost associated with the detection of energyless signals has to be provided by the receiver, much as in a collect call. Technically, sender and receiver are modelled as basic first-quantized systems coupling locally to the relativistic quantum field, i.e., as Unruh-DeWitt particle detectors. This gives rise to a standard quantum channel from the sender to the receiver. Thus, the tools of quantum information can be applied to investigate the combined impact of relativistic and quantum effects on the propagation of information. In the perturbative regime, signals analogous to phase modulation are shown to over- come signals analogous to amplitude modulation: It is shown that the sender has to prepare superpositions of eigenstates, to achieve signalling effects at leading order. Signals from pure energy eigenstates are subdominant, and only appear in next-to-leading order. The classical channel capacities resulting from optimal signalling states are calculated. Analyzing the energy injected into the field by the sender, it is shown that signals reach further in spacetime than the energy radiated by the sender, both for timelike, as well as for lightlike signals. Instead, the energy budget is balanced by the energy that the receiver has to provide when decoupling the detector from the field. This switching cost is particularly sensitive to timelike signals. Timelike signals are also demonstrated to occur between harmonic oscillators coupling to the field inside a cavity. This model could be instrumental for future research, because it can be treated non-perturbatively using Gaussian methods. Such numerical calculations only take into account a finite number of field modes. It is shown that relativistic properties of the field can still be resolved reliably, because the number of necessary modes scales with the desired accuracy, namely following a power law.

Subjects/Keywords: Relativistic Quantum Information; Quantum Information; Quantum Field Theory; Theoretical Physics

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APA (6^th Edition):

Jonsson, R. H. (2016). Decoupling of Information Propagation from Energy Propagation. (Thesis). University of Waterloo. Retrieved from http://hdl.handle.net/10012/10770

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

Chicago Manual of Style (16^th Edition):

Jonsson, Robert H. “Decoupling of Information Propagation from Energy Propagation.” 2016. Thesis, University of Waterloo. Accessed February 22, 2020. http://hdl.handle.net/10012/10770.

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

MLA Handbook (7^th Edition):

Jonsson, Robert H. “Decoupling of Information Propagation from Energy Propagation.” 2016. Web. 22 Feb 2020.

Vancouver:

Jonsson RH. Decoupling of Information Propagation from Energy Propagation. [Internet] [Thesis]. University of Waterloo; 2016. [cited 2020 Feb 22]. Available from: http://hdl.handle.net/10012/10770.

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

Council of Science Editors:

Jonsson RH. Decoupling of Information Propagation from Energy Propagation. [Thesis]. University of Waterloo; 2016. Available from: http://hdl.handle.net/10012/10770

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

University of Waterloo

29. Sachs, Allison. Entanglement Harvesting and Divergences in Unruh-DeWitt Detector Pairs.

Degree: 2017, University of Waterloo

URL: http://hdl.handle.net/10012/12237

► We analyze correlations between pairs of detectors quadratically coupled to real and complex scalar bosonic fields in 3+1 dimensions. This is a first step toward… (more)

Subjects/Keywords: Quantum Field Theory; Unruh-DeWitt Detector; Quantum Information; Relativistic Quantum Information

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APA (6^th Edition):

Sachs, A. (2017). Entanglement Harvesting and Divergences in Unruh-DeWitt Detector Pairs. (Thesis). University of Waterloo. Retrieved from http://hdl.handle.net/10012/12237

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

Chicago Manual of Style (16^th Edition):

Sachs, Allison. “Entanglement Harvesting and Divergences in Unruh-DeWitt Detector Pairs.” 2017. Thesis, University of Waterloo. Accessed February 22, 2020. http://hdl.handle.net/10012/12237.

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

MLA Handbook (7^th Edition):

Sachs, Allison. “Entanglement Harvesting and Divergences in Unruh-DeWitt Detector Pairs.” 2017. Web. 22 Feb 2020.

Vancouver:

Sachs A. Entanglement Harvesting and Divergences in Unruh-DeWitt Detector Pairs. [Internet] [Thesis]. University of Waterloo; 2017. [cited 2020 Feb 22]. Available from: http://hdl.handle.net/10012/12237.

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

Council of Science Editors:

Sachs A. Entanglement Harvesting and Divergences in Unruh-DeWitt Detector Pairs. [Thesis]. University of Waterloo; 2017. Available from: http://hdl.handle.net/10012/12237

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

University of New Mexico

30. Baldwin, Charles. Efficient and Robust Methods for Quantum Tomography.

Degree: Physics & Astronomy, 2016, University of New Mexico

URL: https://digitalrepository.unm.edu/phyc_etds/105

► The development of large-scale platforms that implement quantum information processing protocols requires new methods for verification and validation of quantum behavior. Quantum tomography (QT)… (more)

▼ The development of large-scale platforms that implement quantum information processing protocols requires new methods for verification and validation of quantum behavior. Quantum tomography (QT) is the standard tool for diagnosing quantum states, process, and readout devices by providing complete information about each. However, QT is limited since it is expensive to not only implement experimentally, but also requires heavy classical post-processing of experimental data. In this dissertation, we introduce new methods for QT that are more efficient to implement and robust to noise and errors, thereby making QT a more widely practical tool for current quantum information experiments. The crucial detail that makes these new, efficient, and robust methods possible is prior information about the quantum system. This prior information is prompted by the goals of most experiments in quantum information. Most quantum information processing protocols require pure states, unitary processes, and rank-1 POVM operators. Therefore, most experiments are designed to operate near this ideal regime, and have been tested by other methods to verify this objective. We show that when this is the case, QT can be accomplished with significantly fewer resources, and produce a robust estimate of the state, process, or readout device in the presence of noise and errors. Moreover, the estimate is robust even if the state is not exactly pure, the process is not exactly unitary, or the POVM is not exactly rank-1. Such compelling methods are only made possible by the positivity constraint on quantum states, processes, and POVMs. This requirement is an inherent feature of quantum mechanics, but has powerful consequences to QT. Since QT is necessarily an experimental tool for diagnosing quantum systems, we discuss a test of these new methods in an experimental setting. The physical system is an ensemble of laser-cooled cesium atoms in the laboratory of Prof. Poul Jessen. The atoms are prepared in the hyperfine ground manifold, which provides a large, 16-dimensional Hilbert space to test QT protocols. Experiments were conducted by Hector Sosa-Martinez et al. to demonstrate different QT protocols. We compare the results, and conclude that the new methods are effective for QT. Advisors/Committee Members: Deutsch, Ivan, Jessen, Poul, Francisco, Becerra, Caves, Carl.

Subjects/Keywords: Quantum tomography; Quantum information; Atomic physics; Physics

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APA (6^th Edition):

Baldwin, C. (2016). Efficient and Robust Methods for Quantum Tomography. (Doctoral Dissertation). University of New Mexico. Retrieved from https://digitalrepository.unm.edu/phyc_etds/105

Chicago Manual of Style (16^th Edition):

Baldwin, Charles. “Efficient and Robust Methods for Quantum Tomography.” 2016. Doctoral Dissertation, University of New Mexico. Accessed February 22, 2020. https://digitalrepository.unm.edu/phyc_etds/105.

MLA Handbook (7^th Edition):

Baldwin, Charles. “Efficient and Robust Methods for Quantum Tomography.” 2016. Web. 22 Feb 2020.

Vancouver:

Baldwin C. Efficient and Robust Methods for Quantum Tomography. [Internet] [Doctoral dissertation]. University of New Mexico; 2016. [cited 2020 Feb 22]. Available from: https://digitalrepository.unm.edu/phyc_etds/105.

Council of Science Editors:

Baldwin C. Efficient and Robust Methods for Quantum Tomography. [Doctoral Dissertation]. University of New Mexico; 2016. Available from: https://digitalrepository.unm.edu/phyc_etds/105

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