Control of quantum interference in the quantum eraser

TL;DR

This paper demonstrates an optical quantum eraser that manipulates quantum interference by probabilistically modifying non-orthogonal which-path marker states, advancing understanding of quantum state discrimination.

Contribution

It introduces a probabilistic method to unambiguously alter the inner product of non-orthogonal states for quantum erasure and state discrimination.

Findings

Successfully implemented quantum eraser with non-orthogonal states

Showed control over interference visibility and which-path information

Demonstrated probabilistic state discrimination technique

Abstract

We have implemented an optical quantum eraser with the aim of studying this phenomenon in the context of state discrimination. An interfering single photon is entangled with another one serving as a which-path marker. As a consequence, the visibility of the interference as well as the which-path information are constrained by the overlap (measured by the inner product) between the which-path marker states, which in a more general situation are non-orthogonal. In order to perform which-path or quantum eraser measurements while analyzing non-orthogonal states, we resort to a probabilistic method for the unambiguous modification of the inner product between the two states of the which-path marker in a discrimination-like process.