# Transconductance as a probe of nonlocality of Majorana fermions

## TL;DR

This paper proposes using transconductance measurements in a Kitaev ladder setup to effectively probe the nonlocality of Majorana fermions, enhancing crossed Andreev reflection signals.

## Contribution

It introduces a novel experimental scheme employing Kitaev ladders to amplify crossed Andreev reflection for detecting Majorana nonlocality.

## Key findings

- Transconductance can distinguish nonlocal Majorana states.
- Kitaev ladders enhance crossed Andreev reflection signals.
- Proposed method improves detection of Majorana fermion nonlocality.

## Abstract

Each end of a Kitaev chain in topological phase hosts a Majorana fermion. Zero bias conductance peak is an evidence of Majorana fermion when the two Majorana fermions are decoupled. These two Majorana fermions are separated in space and this nonlocal aspect can be probed when the two are coupled. Crossed Andreev reflection is the evidence of the nonlocality of Majorana fermions. Nonlocality of Majorana fermions has been proposed to be probed by noise measurements since simple conductance measurements cannot probe it due to the almost cancellation of currents from electron tunneling and crossed Andreev reflection. Kitaev ladders on the other hand host subgap Andreev states which can be used to control the relative currents due to crossed Andreev reflection and electron tunneling. We propose to employ Kitaev ladder in series with Kitaev chain and show that the transconductance in this setup can be used as a probe of nonlocality of Majorana fermions by enhancing crossed Andreev reflection over electron tunneling.