Universal Majorana thermoelectric noise

TL;DR

This paper demonstrates that the noise in thermoelectric transport in systems hosting Majorana fermions exhibits universal behavior across all bias voltages, providing a robust signature for detecting Majorana fermions in quantum dots.

Contribution

It introduces a method to identify universal Majorana signatures through thermoelectric noise analysis beyond linear response in quantum dots.

Findings

Thermoelectric noise is universal at any bias voltage in Majorana systems.

Universal ratios between noise and mean current can be used to detect Majorana fermions.

Nonlinear thermoelectric responses reveal signatures independent of system parameters.

Abstract

Thermoelectric phenomena resulting from an interplay between particle flows induced by electric fields and temperature inhomogeneities are extremely insightful as a tool providing substantial knowledge about the microscopic structure of a given system. Tuning, e.g., parameters of a nanoscopic system coupled via tunneling mechanisms to two contacts one may achieve various situations where the electric current induced by an external bias voltage competes with the electric current excited by the temperature difference of the two contacts. Even more exciting physics emerges when the system's electronic degrees freedom split to form Majorana fermions which make the thermoelectric dynamics universal. Here we propose revealing this unique universal signatures of Majorana fermions in strongly nonequilibrium quantum dots via noise of the thermoelectric transport beyond linear response. It is demonstrated that whereas mean thermoelectric quantities are only universal at large bias voltages, the noise of the electric current excited by an external bias voltage and the temperature difference of the contacts is universal at any bias voltage. We provide truly universal, i.e. independent of the system's parameters, thermoelectric ratios between nonlinear response coefficients of the noise and mean current at large bias voltages where experiments may easily be performed to uniquely detect these truly universal Majorana thermoelectric signatures.