# Detecting the universal fractional entropy of Majorana zero modes

## TL;DR

This paper proposes an experimental method to measure a universal entropy change of 1/2 log 2 in Majorana zero modes, providing a clear signature of their nonlocal topological nature and distinguishing them from non-topological states.

## Contribution

It adapts an entropy-measurement scheme to topological systems hosting MZMs, enabling unambiguous detection of their nonlocal topological state through entropy change measurement.

## Key findings

- Proposes a method to measure the 1/2 log 2 entropy change in MZMs.
- Provides a way to distinguish MZMs from non-topological states.
- Suggests an experimental strategy for topological quantum systems.

## Abstract

A pair of Majorana zero modes (MZMs) constitutes a nonlocal qubit whose entropy is $\log 2$. Upon strongly coupling one of the constituent MZMs to a reservoir with a continuous density of states, a universal entropy change of $\frac{1}{2}\log 2$ is expected to be observed across an intermediate temperature plateau. We adapt the entropy-measurement scheme that was the basis of a recent experiment [Hartman et. al., Nat. Phys. 14, 1083 (2018)] to the case of a proximitized topological system hosting MZMs, and propose a method to measure this $\frac{1}{2}\log 2$ entropy change --- an unambiguous signature of the nonlocal nature of the topological state. This approach offers an experimental strategy to distinguish MZMs from non-topological states.