Phase Sensitive Amplification Enabled by Coherent Population Trapping

TL;DR

This paper demonstrates a novel phase sensitive amplification technique using Coherent Population Trapping that enables efficient four-wave mixing with low optical densities, expanding the potential for quantum optics applications.

Contribution

It introduces a new four-wave mixing process enabled by CPT, exploiting degenerate ground states for enhanced phase sensitive amplification.

Findings

Achieved strong phase sensitive gain at low optical densities

Demonstrated four-wave mixing via CPT in a novel configuration

Interpreted results using dark-state polariton formalism

Abstract

We isolate a novel four-wave mixing process, enabled by Coherent Population Trapping (CPT), leading to efficient phase sensitive amplification. This process is permitted by the exploitation of two transitions starting from the same twofold degenerate ground state. One of the transitions is used for CPT, defining bright and dark states from which ultra intense four-wave mixing is obtained via the other transition. This leads to the measurement of a strong phase sensitive gain even for low optical densities and out-of-resonance excitation. The enhancement of four-wave mixing is interpreted in the framework of the dark-state polariton formalism.