Nayana Shah - Low-Dimensional and Nano-scale Superconductors

I. Low-Dimensional

and

Nano-scale Superconductors

A. Pair-breaking Quantum Phase Transitions and Critical Phenomena

Methods, theories, formalisms: Diagrammatic finite temperature Green’s function formalism for disordered electron systems, Bardeen-Cooper-Schrieffer (BCS) theory of superconductivity, Quasi-classical Green’s functions and Usadel Equations, Quantum Field Theory, Renormalization Group and Scaling ideas, Kubo formalism

1. Fluctuation conductivity of thin films and nanowires near a parallel-field-tuned superconducting quantum phase transition with Andrei Lopatin (PD) and Valerii Vinokur

Phys. Rev. Lett. 94, 037003 (2005) arXiv:cond-mat/0404623 Citations

2. Microscopic analysis of the superconducting quantum critical point: Finite temperature crossovers in transport near a pair-breaking quantum phase transition with Andrei Lopatin (PD)

Phys. Rev. B 76, 094511 (2007) arXiv:0705.1890 Citations

3. Universal thermal and electrical transport near the superconductor-metal quantum phase transition in nanowires with Adrian del Maestro (GS), Bernd Rosenow (PD) and Subir Sachdev

Phys. Rev. B 77, 180501 (2008) [Rapid Comm.] arXiv:0708.0687 Citations

B. (Quantum) Phase-slip fluctuations, Coherence and Dynamics

Methods, theories, formalisms: Theoretical modeling of experiments, Proposals made by us for experiments and specific measurements, Heat diffusion equation, Stochastic methods (Quantum Langevin equation for jump processes, master equation derived for our case of ‘delay-differential’ type, Mean first passage time), BCS theory, time-dependent Ginzburg-Landau theory, Langer-Ambegaokar-McCumber-Halperin (LAMH) theory for phase slips, Resistively and capacitively shunted junction (RCSJ) model, Monte-Carlo simulations, Numerical analysis and theoretical fitting of experimental data

Heating due to a phase slip

Modeling of data Individual quantum phase slips are being probed!

1. Inherent stochasticity of superconductive-resistive switching in nanowires with David Pekker and Paul Goldbart

Phys. Rev. Lett. 101, 207001 (2008) arXiv:0709.3971 Citations

2. Individual topological tunnelling events of a quantum field probed through their macroscopic consequences with theorists David Pekker (GS), Tzu-Chieh Wei (PD) and Paul Goldbart; and experimentalists Mitrabhanu Sahu (GS), Myung-Ho Bae (PD), Andrey Rogachev and Alexey Bezryadin

Nature Physics 5, 503 (2009) arXiv:0804.2251 Citations

3. Stochastic dynamics of superconductive-resistive switching in nanowires: Master equation and the mean switching time with theorists David Pekker (GS) and Paul Goldbart; and experimentalists Mitrabhanu Sahu (GS) and Alexey Bezryadin

Phys. Rev. B. 80, 214525 (2009) arXiv:0904.4432 Citations

4. Cratered Lorentzian response of driven microwave superconducting nanowire-bridged resonators: Oscillatory and magnetic-field induced stochastic states with theorists Sarang Gopalakrishnan (GS) and Paul Goldbart; and experimentalists Matthew Brenner (GS), Jaseung Ku (GS), Timothy McArdle (GS), James Eckstein and Alexey Bezryadin

Phys. Rev. B 83, 184503 (2011) arXiv:1101.0817 Citations

5. Dynamics of superconducting nanowires shunted with an external resistor with theorist Dibyendu Roy (PD in my group) and experimentalists Matthew Brenner (GS) and Alexey Bezryadin

Phys. Rev. B 85, 224507 (2012) arXiv:1202.4526 Citations

C. Topological Quantum Phase Transition and Majorana Fermions

Methods, theories, formalisms: BCS theory, Eigen spectrum analysis, Quantum Langevin equations and Green’s function approach for open-quantum-systems that we extended for the case of superconductors, Spectral weight analysis

Kitaev chain with odd and even number of sites

1. Majorana fermions in a topological superconducting wire out of equilibrium: Exact microscopic transport analysis of a p-wave open chain coupled to normal leads with Dibyendu Roy (PD in my group) and Carlos Bolech

Phys. Rev. B 86, 094503 (2012) arXiv:1202.6222 Citations

2. Nature of the zero-bias conductance peak associated with Majorana bound states in topological phases of semiconductor-superconductor hybrid structures with Dibyendu Roy (PD in my group) and Carlos Bolech

arXiv:1303.7036 Citations

3. Accessing different topological classes and types of Majorana edge states in coupled superconducting platforms using perturbations with Sayonee Ray (PD) and Subroto Mukerjee

arXiv:2003.08299

[Note that GS and PD in parenthesis indicate when the co-author was a graduate student or a postdoc at the time of the collaboration. My position at the time of the collaboration is clear from my professional trajectory. By default, co-authors are condensed matter theorists unless specified.]

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