Signatures of Majorana Zero Modes in Spin-Resolved Current Correlations

TL;DR

This paper identifies unique spin-resolved current correlation signatures that distinguish Majorana zero modes from other low-energy states, providing a potential experimental method for their detection.

Contribution

It demonstrates that spin-resolved current correlations can serve as a signature of Majorana bound states, highlighting their anti-correlated behavior at low bias and independence from coupling details.

Findings

Spin-up and spin-down currents are anti-correlated at low bias in Majorana states.

Correlations become uncorrelated at higher bias voltages.

Contrasts with Andreev bound states showing positive correlations.

Abstract

We consider a normal lead coupled to a Majorana bound state. We show that the spin-resolved current correlations exhibit unique features which distinguish Majorana bound states from other low-energy resonances. In particular, the spin-up and spin-down currents from a Majorana bound state are anti-correlated at low bias voltages, and become uncorrelated at higher voltages. This behavior is independent of the exact form of coupling to the lead, and of the direction of the spin polarization. In contrast, an ordinary low-energy Andreev bound state gives rise to a positive correlation between the spin-up and spin-down currents, and this spin-resolved current-current correlation approaches a non-zero constant at high bias voltages. We discuss experimental setups in which this effect can be measured.