Odd-even parity dependent transport in an annular Kitaev chain

TL;DR

This paper studies how magnetic flux and the parity of lattice points affect electron transport in an annular Kitaev chain, revealing parity-dependent effects on transmission mechanisms and robustness against disorder.

Contribution

It provides a detailed analysis of parity and flux effects on transport in an annular Kitaev chain, including the interplay of different reflection processes and disorder robustness.

Findings

Resonant peak symmetry is broken by magnetic flux.

LAR and CAR processes dominate at certain flux values.

Parity-dependent effects are robust under weak disorder.

Abstract

We investigate the impact of magnetic flux and the odd-even parity of lattice points $N$ on electron transport in an annular Kitaev chain, with an explanation provided from the energy band perspective. Three transport mechanisms including direct transmission (DT), local Andreev reflection (LAR) and crossed Andreev reflection (CAR) are considered. In particular, the connection configuration of electrodes to different lattice sites is studied, where the case that the two electrodes connected to the sites are aligned along a diameter is called as symmetric connection and otherwise as asymmetric connections. For even $N$ and asymmetric connection, the vanished LAR and CAR in symmetric connection will emerge as peaks. A more prominent observation is that the symmetry of the two resonant peaks due to DT processes located at $\Phi = N\pi/3$ and $\Phi = 2N\pi/3$ for symmetric connection will be broken, and the peak at $\Phi = N\pi/3$ will be largely reduced, where $\Phi$ is the magnetic flux. Moreover, the peaks around $\Phi = N\pi/3$ due to LAR and CAR processes grows drastically even larger than that from DT. For LAR and CAR processes, there is no peak around $\Phi = 2N\pi/3$ and transmission due to these two processes are completely suppressed for $\Phi>N\pi/2$. Moreover, it is found that the energy bands vary with $\Phi$ in a period of $N\pi$ and $2N\pi$ for even or odd $N$. We finally systematically analyze the influence of weak disorder on transport and demonstrate that these parity-dependent effects are robust in the presence of disorder. These behaviors reflect a complicated competition from DT, LAR and CAR processes and the parity of the lattice number in the Kitaev ring, which will be interested for the quantum device based on Kitaev chain.