Extracting the Anyonic Exchange Phase from Hanbury Brown-Twiss Correlations

TL;DR

This paper demonstrates how a Hanbury Brown-Twiss interferometer can directly measure the fractional exchange phase of quasiparticles in fractional quantum Hall systems, overcoming previous ambiguities.

Contribution

It introduces a novel interferometry method using cross geometry to directly access the fractional exchange phase in quantum Hall devices.

Findings

The exchange phase can be extracted from phase shifts in Aharonov-Bohm oscillations.

The method distinguishes exchange phase from braiding phase ambiguities.

Non-equilibrium Keldysh calculations support the experimental feasibility.

Abstract

In recent years, interferometry experiments in fractional quantum Hall devices have reported signatures of a fractional braiding phase for quasiparticles. It was noted, however, that the braiding phase alone does not uniquely determine the exchange phase because of a $\pi$-ambiguity. Here we analyze a Hanbury Brown-Twiss interferometer in a cross geometry that provides direct access to the fractional exchange phase. Using a non-equilibrium Keldysh calculation in an experimentally relevant regime, we show that the exchange phase can be obtained as the phase shift between Aharonov-Bohm oscillations in a single-particle interference current and those in the current cross-correlation arising from two-particle interference.