Observation of quantum noise reduction in a Raman amplifier via quantum correlation between atom and light

TL;DR

This paper demonstrates quantum noise reduction in a Raman amplifier by exploiting atom-light correlations, achieving over 3.5 dB noise suppression, and introduces a hybrid atom-light interferometer for quantum-enhanced sensing.

Contribution

The study experimentally shows quantum noise reduction in a Raman amplifier through atomic and light correlation manipulation, and proposes a new hybrid interferometer for quantum sensing.

Findings

Achieved over 3.5 dB quantum noise reduction.

Demonstrated atomic-light quantum correlation in Raman amplification.

Proposed a quantum-entangled atom-light hybrid interferometer.

Abstract

Any amplifier requires coupling to its internal degrees of freedom for energy gain. This coupling introduces extra quantum noise to the output. On the other hand, if the internal degree of the amplifier can be accessed and manipulated, we can manage and even reduce the quantum noise of the amplifier's output. In this paper, we present an experiment to reduce the quantum noise of a Raman amplifier by preparing the atomic medium in a correlated state with the Stokes light field. We report an observation of quantum noise reduction of more than 3.5 dB in the atomic Raman amplification process. From another perspective, the Raman amplifier at high gain in turn serves as a measurement tool for the quantum correlation between the atom and light. Furthermore, such a scheme, when viewed as a whole, also forms a quantum-entangled atom-light hybrid interferometer that can lead to quantum-enhanced sensors.