Multi-photon state engineering by heralded interference between single photons and coherent states

TL;DR

This paper presents a versatile method for generating multi-photon nonclassical states through heralded interference, enabling tunable quantum states with potential applications in quantum technologies.

Contribution

The authors introduce a novel quantum catalysis protocol that allows flexible creation of multi-photon nonclassical states without relying on weak nonlinearities.

Findings

Achieved squeezing up to 1.25 dB.

Demonstrated anti- and super-bunched photon statistics.

Produced states with over 90% fidelity to displaced coherent superpositions.

Abstract

We develop a technique for generating multi-photon nonclassical states via interference between coherent and Fock states using quantum catalysis. By modulating the coherent field strength, the number of catalyst photons and the ratio of the beam splitter upon which they interfere, a wide range of nonclassical phenomena can be created, including squeezing of up to 1.25 dB, anti- and super-bunched photon statistics and states exhibiting over 90% fidelity to displaced coherent superposition states. We perform quantum catalysis experimentally, showing tunability into the nonclassical regime. Our protocol is not limited by weak nonlinearities that underlie most known strategies of preparing multi-photon nonclassical states. Successive iterations of this protocol can lead to direct control over the weights of higher-order terms in the Fock basis, paving the way towards conditional preparation of "designer" multi-photon states for applications in quantum computation, communication and metrology.