Two-photon interference: the Hong-Ou-Mandel effect

TL;DR

This paper reviews the history, fundamental principles, and diverse applications of two-photon interference, especially the Hong-Ou-Mandel effect, highlighting its significance in advancing quantum technologies over the past three decades.

Contribution

It provides a comprehensive overview of the progress and applications of two-photon interference, emphasizing its unique quantum properties and experimental demonstrations with various particles.

Findings

Two-photon interference has no classical analogue.

It has been observed with massive particles like electrons and atoms.

The effect underpins many quantum computing and communication applications.

Abstract

Nearly 30 years ago, two-photon interference was observed, marking the beginning of a new quantum era. Indeed, two-photon interference has no classical analogue, giving it a distinct advantage for a range of applications. The peculiarities of quantum physics may now be used to our advantage to outperform classical computations, securely communicate information, simulate highly complex physical systems and increase the sensitivity of precise measurements. This separation from classical to quantum physics has motivated physicists to study two-particle interference for both fermionic and bosonic quantum objects. So far, two-particle interference has been observed with massive particles, among others, such as electrons and atoms, in addition to plasmons, demonstrating the extent of this effect to larger and more complex quantum systems. A wide array of novel applications to this quantum effect is to be expected in the future. This review will thus cover the progress and applications of two-photon (two-particle) interference over the last three decades.