Quantum Indistinguishability by Path Identity: The awakening of a sleeping beauty

TL;DR

This paper reviews the concept of quantum path identity, where photon paths are made indistinguishable without erasing information, leading to advances in imaging, spectroscopy, and quantum information science.

Contribution

It introduces the idea of path identity and comprehensively reviews recent developments and applications across various quantum science fields.

Findings

Path identity enables new quantum imaging techniques.

It has led to novel spectroscopy methods.

Applications include advancements in quantum information processing.

Abstract

Two photon-pair creation processes can be arranged such that the paths of the emitted photons are identical. Thereby the path information is not erased but is never born in the first place. In addition to its implications for fundamental physics, this concept has recently led to a series of discoveries in the fields of imaging, spectroscopy, and quantum information science. Here we present the idea of path identity and provide a comprehensive review of the recent developments.