Quantum correlations by four-wave mixing in an atomic vapor in a non-amplifying regime: a quantum beam splitter for photons

TL;DR

This paper demonstrates that four-wave mixing in rubidium vapor can generate quantum correlations without amplification, effectively functioning as a non-classical beam splitter for photons, with potential applications in quantum information processing.

Contribution

It introduces and experimentally verifies a novel regime of four-wave mixing that produces quantum correlations without amplification, acting as a quantum beam splitter.

Findings

Achieved up to 9.2 dB of intensity squeezing below the standard quantum limit.

Demonstrated quantum correlation generation without overall amplification.

Validated the four-wave mixing setup as a non-classical beam splitter.

Abstract

We study the generation of intensity quantum correlations using four-wave mixing in a rubidium vapor. The absence of cavity in these experiments allows to deal with several spatial modes simultaneously. In the standard, amplifying, configuration, we measure relative intensity squeezing up to 9.2 dB below the standard quantum limit. We also theoretically identify and experimentally demonstrate an original regime where, despite no overall amplification, quantum correlations are generated. In this regime a four-wave mixing set-up can therefore play the role of a photonic beam splitter with non--classical properties, i.e. a device that splits a coherent state input into two quantum correlated beams.