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TT: Fachverband Tiefe Temperaturen

TT 53: Topology: Majorana Physics

TT 53.4: Vortrag

Donnerstag, 19. März 2020, 10:15–10:30, HSZ 103

Linear and non-linear transport in a finite Kitaev chain — •Nico Leumer¹, Bhaskaran Muralidharan², Magdalena Marganska¹, and Milena Grifoni¹ — ¹University of Regensburg — ²Indian Institute of Technology Bombay

The Kitaev chain is an archetypal model for one dimensional topological superconductivity and known for the emergence of so-called Majorana fermions [1, 2]. These states yield a 2 e²/h signature in the conductance of a transport set up.

We study in depth both linear and non-linear transport across a finite Kitaev chain. The simplicity of the Kitaev chain allows us an exact and analytical treatment for the spectrum [3], its eigenstates as well as of the Green’s function matrix elements necessary for the transport calculations. Setting up the transport formulation of the finite Kitaev chain via the non-equilibrium Green’s function approach, we identify the transport signatures arising from Majorana zero modes and generic ultra low-lying excitations. We show that the coupling to the contacts changes the signatures as well as modulates the topological phase diagram of the Majorana zero modes, when compared with that of a pristine wire. Further, precise quantization of conductance is only found along contact-broadened Majorana lines; the latter sustain exact MZMs in the finite, isolated Kitaev chain. In exploring the non-linear transport, we note clearly the contributions from the Andreev, the direct transfer and the crossed Andreev processes to the currents.

[1] A. Y. Kitaev, Phys. Usp. 44, 131 (2001)

[2] R. Aguado, Riv. Nuovo Cimento 40, 16 (2017)

[3] N. Leumer et al., arXiv:1909.10971