Towards Simultaneous Observation of Path and Interference of Single Photon in a Modified Mach-Zehnder Interferometer

TL;DR

This paper demonstrates a modified Mach-Zehnder interferometer that allows simultaneous observation of wave and particle properties of a single photon, surpassing the traditional wave-particle duality limit.

Contribution

It introduces a novel interferometer setup with a weakly-scattering prism that breaks the orthodox wave-particle duality limit, challenging foundational quantum principles.

Findings

Interference visibility up to 0.97

Path distinguishability of 0.83

Square(V)+square(D)=1.63 exceeds the limit

Abstract

Classical wisdom of wave-particle duality says that it is impossible to observe simultaneously the wave and particle nature of microscopic object. Mathematically the principle requests that the interference visibility V and which-path distinguishability D satisfy an orthodox limit of square(V)+square(D)<=1. This work presents a new wave-particle duality test experiment with single photon in a modified Mach-Zehnder interferometer and convincingly show the possibility of breaking the limit. The key element of the interferometer is a weakly-scattering total-internal reflection prism surface, which exhibits pronounced single-photon interference with a visibility up to 0.97 and simultaneously provides path distinguishability of 0.83. Apparently square(V)+square(D)=1.63 far exceeds the orthodox limit set by the principle of wave-particle duality for single photon. It is expected that more delicate experiments in future should be able to demonstrate the ultimate regime of square(V)+square(D) approaching 2 and shed new light on the foundations of contemporary quantum mechanics.