Multi-photon entanglement and interferometry

TL;DR

This paper reviews the rapid progress in multi-photon entanglement and interferometry, highlighting theoretical and experimental advances in quantum mechanics tests, quantum communication, and linear optical quantum computing.

Contribution

It provides a comprehensive overview of recent developments in creating multi-photon entanglement and their applications in fundamental tests and quantum information processing.

Findings

Demonstrated violations of local realism with multi-photon states

Reviewed quantum protocols like teleportation and entanglement purification

Summarized progress in linear optical quantum computing

Abstract

Multi-photon interference reveals strictly non-classical phenomena. Its applications range from fundamental tests of quantum mechanics to photonic quantum information processing, where a significant fraction of key experiments achieved so far comes from multi-photon state manipulation. We review the progress, both theoretical and experimental, of this rapidly advancing research. The emphasis is given to the creation of photonic entanglement of various forms, tests of the completeness of quantum mechanics (in particular, violations of local realism), quantum information protocols for quantum communication (e.g., quantum teleportation, entanglement purification and quantum repeater), and quantum computation with linear optics. We shall limit the scope of our review to "few photon" phenomena involving measurements of discrete observables.