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You searched for +publisher:"Brown University" +contributor:("Feldman, Dima"). Showing records 1 – 3 of 3 total matches.

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1. Li, Feifei. Transport in Low Dimensional Strongly Correlated Electronic System.

Degree: PhD, Physics, 2009, Brown University

This thesis presents two theoretical investigations on transport in low dimensional strongly correlated electronic systems. In the study of one dimensional system, we demonstrate that spin current can be generated by an ac voltage in a one-channel quantum wire with strong repulsive electron interactions in the presence of a non-magnetic impurity and uniform static magnetic field. We show that in a certain range of voltages, the spin current can exhibit a power dependence on the ac voltage bias with a negative exponent. The spin current expressed in units of \hbar/2 per second can become much larger than the charge current in units of the electron charge per second. The spin current generation requires neither spin-polarized particle injection nor time-dependent magnetic fields. In the study of on-Abelian statistics in two dimensional quantum Hall system, we suggest an experiment which can determine the physical state for the ν=5/2 quantum Hall plateau. The proposal involves transport measurements in the geometry with three quantum Hall edges connected by two quantum point contacts. In contrast to interference experiments, this approach can distinguish the Pfaffian and anti-Pfaffian states as well as different states with identical Pfaffian or anti-Pfaffian statistics. In addition, the transport is not sensitive to the fluctuations of the number of the quasiparticles trapped in the system. Advisors/Committee Members: Feldman, Dima (director), Marston, Brad (reader), Valles, James (reader).

Subjects/Keywords: Luttinger Liquid

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APA (6th Edition):

Li, F. (2009). Transport in Low Dimensional Strongly Correlated Electronic System. (Doctoral Dissertation). Brown University. Retrieved from https://repository.library.brown.edu/studio/item/bdr:203/

Chicago Manual of Style (16th Edition):

Li, Feifei. “Transport in Low Dimensional Strongly Correlated Electronic System.” 2009. Doctoral Dissertation, Brown University. Accessed January 22, 2021. https://repository.library.brown.edu/studio/item/bdr:203/.

MLA Handbook (7th Edition):

Li, Feifei. “Transport in Low Dimensional Strongly Correlated Electronic System.” 2009. Web. 22 Jan 2021.

Vancouver:

Li F. Transport in Low Dimensional Strongly Correlated Electronic System. [Internet] [Doctoral dissertation]. Brown University; 2009. [cited 2021 Jan 22]. Available from: https://repository.library.brown.edu/studio/item/bdr:203/.

Council of Science Editors:

Li F. Transport in Low Dimensional Strongly Correlated Electronic System. [Doctoral Dissertation]. Brown University; 2009. Available from: https://repository.library.brown.edu/studio/item/bdr:203/

2. Law, Kam Tuen. Probing Abelian and Non-Abelian Statistics in Fractional Quantum Hall States.

Degree: PhD, Physics, 2008, Brown University

Particles other than bosons and fermions can exist in two dimensions. One possibility is that when one particle makes a circle around another particle the total many-particle wave function acquires a non-trivial phase factor. Such particles are called Abelian anyons. In a more exotic situation, the action of moving one particle around other particles or in other words, particle braiding, is represented by a unitary matrix acting on the quantum-state vector. If the braiding matrices do not commute with each other, the particles are called non-Abelian anyons.\ The existence of both Abelian and non-Abelian anyons has been predicted in Fractional Quantum Hall systems. Quasiparticles in the Laughlin states with filling factor ν=1/(2m+1) are Abelian anyons. On the other hand, quasiparticles in the Moore-Read and Read-Rezayi states with filling factors ν=5/2 and ν=12/5 , respectively, are proposed to be non-Abelian anyons. However, no experimental observation of the exchange statistics of identical anyons has been reported so far. \ In this thesis we demonstrate that the current and shot noise in the topologically nontrivially set-up of the electronic Mach-Zehnder interferometer can be used to detect anyonic statistics. The transport is not sensitive to the fluctuations of the topological charge inside the interferometer and hence the interference picture is not destroyed by the tunneling of low-energy neutral excitations between the edges and localized states in the interferometer. The current and noise exhibit non-Analytic dependences on small tunneling amplitudes. The low-temperature Fano factor is always below 1 for Abelian anyons and can greatly exceed 1 for non-Abelian statistics. Advisors/Committee Members: Feldman, Dima (director), Mitrovic, Vesna (reader), Ying, See-Chen (reader).

Subjects/Keywords: Anyonic Statistics

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

APA (6th Edition):

Law, K. T. (2008). Probing Abelian and Non-Abelian Statistics in Fractional Quantum Hall States. (Doctoral Dissertation). Brown University. Retrieved from https://repository.library.brown.edu/studio/item/bdr:17/

Chicago Manual of Style (16th Edition):

Law, Kam Tuen. “Probing Abelian and Non-Abelian Statistics in Fractional Quantum Hall States.” 2008. Doctoral Dissertation, Brown University. Accessed January 22, 2021. https://repository.library.brown.edu/studio/item/bdr:17/.

MLA Handbook (7th Edition):

Law, Kam Tuen. “Probing Abelian and Non-Abelian Statistics in Fractional Quantum Hall States.” 2008. Web. 22 Jan 2021.

Vancouver:

Law KT. Probing Abelian and Non-Abelian Statistics in Fractional Quantum Hall States. [Internet] [Doctoral dissertation]. Brown University; 2008. [cited 2021 Jan 22]. Available from: https://repository.library.brown.edu/studio/item/bdr:17/.

Council of Science Editors:

Law KT. Probing Abelian and Non-Abelian Statistics in Fractional Quantum Hall States. [Doctoral Dissertation]. Brown University; 2008. Available from: https://repository.library.brown.edu/studio/item/bdr:17/

3. Stewart, Michael D. Superconductor to Insulator Transitions in Amorphous Nanohoneycomb Films.

Degree: PhD, Physics, 2008, Brown University

Two dimensional electronic systems exhibit a wide variety of phenomena including the quantum Hall effect, weak and strong localization, and metal-insulator transitions, including the superconductor to insulator transition (SIT). In each case the possibility of a universal explanation, independent of the microscopic details of the system, has tantalized researchers. In some cases, such as the temperature dependence of the conductance of metal films, or the spacing of resistance plateaus in the Hall effect, universal behavior is without doubt. Universal explanations of the amorphous film SIT revolve around the dirty Boson model, in which the sharp rise in the resistance of a film at low temperature is due to the localization of Cooper pairs. The existence of long-lived Cooper pairs in an electrically insulating system, the central assumption of the model, has remained in doubt because some measurements support the assertion and others refute it. This thesis addresses this experimental dissonance by investigating the SITs of amorphous Bismuth films perforated with a regular nanohoneycomb (NHC) array of holes. The nanoscale perforations allow a direct measurement of phase coherent Cooper pairs with an applied magnetic field. On the insulating side of the disorder driven SIT the resistance as a function of magnetic field oscillates with a period, h/2eS, where S is the area of a unit cell of holes. The 2e period betrays the presence of localized Cooper pairs in an electrically insulating state. The magnetoresistance of weak superconducting films reveals several SITs which qualitatively resemble the disorder driven SIT. The behavior of these transitions borrows heavily from both sides of a dichotomy exhibited by different materials through their field driven SITs. NHC films show activated resistances and a large peak in the magnetoresistance, analogous to the more spectacular behavior of some materials. However, they also show a weak, almost metallic, temperature dependence for a range of fields near the SIT, not unlike the metallic phase of unpatterned Bismuth and other materials. These results suggest that an underlying multiply connected geometry in ostensibly amorphous, unpatterned films may account for some of the range of material dependent behavior. Advisors/Committee Members: Valles, James (director), Feldman, Dima (reader), Ling, Xinsheng (reader).

Subjects/Keywords: superconductor insulator transition

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

APA (6th Edition):

Stewart, M. D. (2008). Superconductor to Insulator Transitions in Amorphous Nanohoneycomb Films. (Doctoral Dissertation). Brown University. Retrieved from https://repository.library.brown.edu/studio/item/bdr:48/

Chicago Manual of Style (16th Edition):

Stewart, Michael D. “Superconductor to Insulator Transitions in Amorphous Nanohoneycomb Films.” 2008. Doctoral Dissertation, Brown University. Accessed January 22, 2021. https://repository.library.brown.edu/studio/item/bdr:48/.

MLA Handbook (7th Edition):

Stewart, Michael D. “Superconductor to Insulator Transitions in Amorphous Nanohoneycomb Films.” 2008. Web. 22 Jan 2021.

Vancouver:

Stewart MD. Superconductor to Insulator Transitions in Amorphous Nanohoneycomb Films. [Internet] [Doctoral dissertation]. Brown University; 2008. [cited 2021 Jan 22]. Available from: https://repository.library.brown.edu/studio/item/bdr:48/.

Council of Science Editors:

Stewart MD. Superconductor to Insulator Transitions in Amorphous Nanohoneycomb Films. [Doctoral Dissertation]. Brown University; 2008. Available from: https://repository.library.brown.edu/studio/item/bdr:48/

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