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University of Colorado

1. Tan, Ting Rei. High-Fidelity Entangling Gates with Trapped-Ions.

Degree: PhD, Physics, 2016, University of Colorado

URL: https://scholar.colorado.edu/phys_gradetds/224

Quantum entangling logic gates are key ingredients for the implementation of a quantum information processing device. In this thesis, we focus on experimental implementations of three types of entangling geometric-phase gates with trapped ions, which rely on the effective spin-spin interactions generated with state-dependent forces. First, a mixed-species entangling gate is demonstrated using a beryllium and a magnesium ion to create a Bell state with a fidelity of 0.979(1). Combined with single-qubit gates, we use this mixed-species gate to implement controlled-NOT and SWAP gates. Second, we implement a high-fidelity universal gate set with beryllium ions. Single-qubit gates with error per gate of 3.8(1)x10^{-5} are achieved. By creating a Bell state with a deterministic two-qubit entangling gate, we deduce a gate error as low as 8(4)x10^{-4}. Third, a novel two-qubit entangling gate with dynamical decoupling built-in is demonstrated with a fidelity of 0.974(4). This gate is robust against qubit dephasing errors and offers simplifications in experimental implementation compared to some other gates with trapped ions. Errors in the above implementations are evaluated and methods to further reduce imperfections are discussed. In a separate experiment, correlated measurements made on pairs of ions violate a "chained" Bell inequality obeyed by any local-realistic theory. The lowest chained Bell inequality parameter determined from our measurements is 0.296(12), this value is significantly lower than 0.586, the minimum value derived from a perfect Clauser-Horne-Shimony-Horne (CHSH) Bell inequality experiment. Furthermore, our CHSH Bell inequality results provide a device-independent certification of the deterministically created Bell states.
*Advisors/Committee Members: David J. Wineland, Emanuel Knill, Ana Maria Rey, Jun Ye, Eric Cornell.*

Subjects/Keywords: Atomic; molecular; and optical physics; Chained Bell inequality; Mixed-species entangling gate; Quantum entanglement; Quantum information; Trapped ions; Atomic, Molecular and Optical Physics; Physics; Quantum Physics

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

APA (6^{th} Edition):

Tan, T. R. (2016). High-Fidelity Entangling Gates with Trapped-Ions. (Doctoral Dissertation). University of Colorado. Retrieved from https://scholar.colorado.edu/phys_gradetds/224

Chicago Manual of Style (16^{th} Edition):

Tan, Ting Rei. “High-Fidelity Entangling Gates with Trapped-Ions.” 2016. Doctoral Dissertation, University of Colorado. Accessed February 27, 2021. https://scholar.colorado.edu/phys_gradetds/224.

MLA Handbook (7^{th} Edition):

Tan, Ting Rei. “High-Fidelity Entangling Gates with Trapped-Ions.” 2016. Web. 27 Feb 2021.

Vancouver:

Tan TR. High-Fidelity Entangling Gates with Trapped-Ions. [Internet] [Doctoral dissertation]. University of Colorado; 2016. [cited 2021 Feb 27]. Available from: https://scholar.colorado.edu/phys_gradetds/224.

Council of Science Editors:

Tan TR. High-Fidelity Entangling Gates with Trapped-Ions. [Doctoral Dissertation]. University of Colorado; 2016. Available from: https://scholar.colorado.edu/phys_gradetds/224

University of Colorado

2. Kaufman, Adam M. Laser-Cooling Atoms to Indistinguishability: Atomic Hong-Ou-Mandel Interference and Entanglement Through Spin-Exchange.

Degree: PhD, Physics, 2015, University of Colorado

URL: https://scholar.colorado.edu/phys_gradetds/140

In this thesis, I describe the development of and scientific results from a new platform for creating ultracold atoms via single-atom control. We employ Raman-sideband cooling to isolated bosonic ^{87}Rb atoms confined within sub-micron optical tweezers, yielding single particle three- dimensional ground-state fractions of 90%. We create multiple, independent, mobile optical tweezers, which simultaneously allows multi-particle studies with single-atom microscopy and highly tunable length-scales. We employ this toolset in both of the main experiments discussed in this thesis. In one experiment, we observe Hong-Ou-Mandel interference of two bosonic atoms, each of which is independently prepared in spatially separated optical tweezers. The interference we observe is a direct consequence of the purity of the single particle quantum states produced, and the indistinguishability of the atoms. In a second experiment, we introduce a spin-degree of freedom and exploit spin-exchange dynamics, driven by the quantum-statistics of the particles, to create a spin-entangled pair of spatially separated atoms.
*Advisors/Committee Members: Cindy A. Regal, Ana Maria Rey, Deborah S. Jin, David J. Wineland, Juan Restrepo.*

Subjects/Keywords: Laser cooling; Quantum control; Single atoms; ultracold atoms; Atomic, Molecular and Optical Physics; Quantum Physics

Record Details Similar Records

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

APA (6^{th} Edition):

Kaufman, A. M. (2015). Laser-Cooling Atoms to Indistinguishability: Atomic Hong-Ou-Mandel Interference and Entanglement Through Spin-Exchange. (Doctoral Dissertation). University of Colorado. Retrieved from https://scholar.colorado.edu/phys_gradetds/140

Chicago Manual of Style (16^{th} Edition):

Kaufman, Adam M. “Laser-Cooling Atoms to Indistinguishability: Atomic Hong-Ou-Mandel Interference and Entanglement Through Spin-Exchange.” 2015. Doctoral Dissertation, University of Colorado. Accessed February 27, 2021. https://scholar.colorado.edu/phys_gradetds/140.

MLA Handbook (7^{th} Edition):

Kaufman, Adam M. “Laser-Cooling Atoms to Indistinguishability: Atomic Hong-Ou-Mandel Interference and Entanglement Through Spin-Exchange.” 2015. Web. 27 Feb 2021.

Vancouver:

Kaufman AM. Laser-Cooling Atoms to Indistinguishability: Atomic Hong-Ou-Mandel Interference and Entanglement Through Spin-Exchange. [Internet] [Doctoral dissertation]. University of Colorado; 2015. [cited 2021 Feb 27]. Available from: https://scholar.colorado.edu/phys_gradetds/140.

Council of Science Editors:

Kaufman AM. Laser-Cooling Atoms to Indistinguishability: Atomic Hong-Ou-Mandel Interference and Entanglement Through Spin-Exchange. [Doctoral Dissertation]. University of Colorado; 2015. Available from: https://scholar.colorado.edu/phys_gradetds/140

University of Colorado

3. Lin, Yiheng. Quantum Entanglement Generation in Trapped Ions Using Coherent and Dissipative Methods.

Degree: PhD, Physics, 2015, University of Colorado

URL: https://scholar.colorado.edu/phys_gradetds/150

Entangled states are a key resource in fundamental quantum physics, quantum cryptography, and quantum computation. In this thesis, we focus on the demonstrations of two novel methods to generate entanglement. First, we implement dissipative production of a maximally entangled steady state on two trapped ions. Dissipative and coherent processes are combined and implemented in a continuous time-independent fashion, analogous to optical pumping of atomic states, continuously driving the system towards the steady entangled state. With this method, we obtain a Bell state fidelity up to 0.89(2). Second, we propose and demonstrate a novel coherent process to confine quantum evolution in a subspace between an initial separable state and the target entangled state. We demonstrate this scheme on two and three ions obtaining a Bell state fidelity up to 0.992(2). Both of these methods are robust against certain types of experimental noise and decoherence. Additionally, we demonstrate sympathetic cooling of ion chains to near the ground
state of motion with an electromagnetically-induced-transparency (EIT) method. This results in roughly an order of magnitude faster cooling time while using significantly lower laser power compared to the conventional resolved sideband cooling method. These techniques may be helpful for scaled-up quantum computing.
*Advisors/Committee Members: David J. Wineland, James Thompson, Cindy Regal, Eric Cornell, David Jonas.*

Subjects/Keywords: open quantum system; quantum computing; quantum entanglement; quantum information; quantum optics; trapped ion experiment; Atomic, Molecular and Optical Physics; Optics; Quantum Physics

Record Details Similar Records

❌

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

APA (6^{th} Edition):

Lin, Y. (2015). Quantum Entanglement Generation in Trapped Ions Using Coherent and Dissipative Methods. (Doctoral Dissertation). University of Colorado. Retrieved from https://scholar.colorado.edu/phys_gradetds/150

Chicago Manual of Style (16^{th} Edition):

Lin, Yiheng. “Quantum Entanglement Generation in Trapped Ions Using Coherent and Dissipative Methods.” 2015. Doctoral Dissertation, University of Colorado. Accessed February 27, 2021. https://scholar.colorado.edu/phys_gradetds/150.

MLA Handbook (7^{th} Edition):

Lin, Yiheng. “Quantum Entanglement Generation in Trapped Ions Using Coherent and Dissipative Methods.” 2015. Web. 27 Feb 2021.

Vancouver:

Lin Y. Quantum Entanglement Generation in Trapped Ions Using Coherent and Dissipative Methods. [Internet] [Doctoral dissertation]. University of Colorado; 2015. [cited 2021 Feb 27]. Available from: https://scholar.colorado.edu/phys_gradetds/150.

Council of Science Editors:

Lin Y. Quantum Entanglement Generation in Trapped Ions Using Coherent and Dissipative Methods. [Doctoral Dissertation]. University of Colorado; 2015. Available from: https://scholar.colorado.edu/phys_gradetds/150