Quantum coherence versus interferometric visibility in a biased Mach-Zehnder interferometer

TL;DR

This paper explores how quantum coherence can be a more accurate measure than interferometric visibility in biased Mach-Zehnder interferometers, supported by theoretical analysis and IBM quantum computer experiments.

Contribution

It demonstrates that interferometric visibility may fail to reflect quantum coherence in biased MZIs, providing a new perspective on quantifying wave-particle duality.

Findings

IVI does not always reflect quantum coherence in biased MZIs

Quantum coherence provides a better measure of wave aspect in certain setups

Experimental verification using IBM quantum computers confirms theoretical predictions

Abstract

The double-slit interferometer and the Mach-Zehnder interferometer (MZI) with balanced beam splitters are prototypical setups for investigating the quantum wave-particle duality. These setups induced a quantitative association of interferometric visibility (IVI) with the wave aspect of a single quantum system (WAQ). Recently, it was realized that quantum coherence (QC) can be better suited than IVI for quantifying the WAQ in complementarity relations. In this article, we investigate a MZI with biased beam splitters both in the input and the output, and we show that in some cases the IVI is not adequate to quantify the WAQ since it does not reflect the behavior of the quantum coherence, even for a bi-dimensional closed quantum system. Using IBM quantum computers, we experimentally verify our theoretical findings by doing a full quantum simulation of the optical MZI with biased beam splitters.