Regensburg 2016 – wissenschaftliches Programm

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TT: Fachverband Tiefe Temperaturen

TT 68: Transport: Majorana Fermions

TT 68.9: Vortrag

Donnerstag, 10. März 2016, 12:45–13:00, H19

Majorana tunneling entropy — •Sergey Smirnov — University of Regensburg, D-93040 Regensburg, Germany

In thermodynamics a macroscopic state of a system results from a number of its microscopic states. This number is given by the exponent of the system’s entropy. In non-interacting systems with discrete energy spectra, such as large scale quantum dots, the entropy as a function of the temperature has a plateau shape with integer values of the exponent of the entropy on these plateaus. Plateaus with non-integer values are fundamentally forbidden and would be thermodynamically infeasible.

Here we investigate the entropy of a non-interacting quantum dot coupled via tunneling to normal metals with continuum spectra as well as to topological superconductors. We show [1] that the entropy may have non-integer plateaus if the topological superconductors support weakly overlapping Majorana bound states. This brings a fundamental change in the thermodynamics of the quantum dot whose specific heat acquires low temperature Majorana peaks which should be absent according to the conventional thermodynamics. We also provide a fundamental thermodynamic understanding of the transport properties, such as the linear conductance. Thus, demonstrating thermodynamic signatures of Majorana fermions, we, on the other hand, connect them to other fields, such as transport, advancing their further understanding on a deep fundamental basis.
S. Smirnov, PRB 92, 195312 (2015).