Majorana entropy revival via tunneling phases

TL;DR

This paper proposes a method to reliably measure Majorana entropy in nanoscale devices by tuning tunneling phases, overcoming challenges posed by realistic tunneling processes that obscure the entropy signature.

Contribution

It introduces a mechanism of Majorana entropy revival through tunneling phase control, enabling accurate detection of Majorana states in practical experimental setups.

Findings

Tunneling phases critically influence Majorana entropy measurements.

Adjusting tunneling phases can restore the universal Majorana entropy plateau.

Practical parameter examples show feasibility in current laboratories.

Abstract

Measuring the Majorana entropy $S_M=k_B\log(2^\frac{1}{2})$ may uniquely reveal whether an initial equilibrium state of a nanoscale device is of Majorana nature and subsequent operations deal with an essentially nonlocal pair of non-Abelian Majorana bound states and not with trivial or other accidental non-Abelian states. However, in realistic setups both Majorana modes are inevitably involved in tunneling processes. We show that even when the tunneling amplitude of one Majorana mode is significantly suppressed, the Majorana entropy ruins and straightforward experiments will in general detect entropy $S\ll S_M$. To avoid this general problem we present a mechanism of the Majorana entropy revival via the tunneling phases of the Majorana modes and demonstrate that to successfully observe the universal Majorana plateau $S=S_M$ one should intelligently tune the tunneling phases instead of leaving them uncontrolled. Practical feasibility of appropriate Majorana entropy measurements is supported by an example with parameters well achievable in modern labs.