Phase sensitive amplification enabled by coherent population trapping

P Neveu,F Bretenaker,C Banerjee,J Lugani,F Goldfarb,E Brion

doi:10.1088/1367-2630/aadb79

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.

Highlights

Optical parametric amplification processes have been widely studied for their unique noise properties and their many possible applications in metrology [1], imaging [2] and telecommunications [3]. They have been implemented in different media such as nonlinear crystals and waveguides [4] through three-wave mixing (χ(2) process) or fibers [5] through four-wave mixing (χ(3) process) (FWM): one or two strong driving pump field(s) play the role of a reservoir of photons for a signal and an idler fields
Very large quantum noise reductions up to 15 dB have been achieved using crystals [8], but down-converted photons are spectrally mismatched with atomic systems used for quantum memories and phase sensitive amplification (PSA) achieved directly through FWM in atomic systems like alkali vapors is a subject of active interest [9,10,11]
To understand the underlying mechanism, it is interesting to switch to the coherent population trapping (CPT) dark (∣-ñg) and bright (∣+ñg) state basis defined by the coupling field, which assigns different transitions to the coupling and probe fields [22]:

Summary

August 2018

Any further distribution of We isolate a novel four-wave mixing process, enabled by coherent population trapping (CPT), leading this work must maintain to efficient phase sensitive amplification. This process is permitted by the exploitation of two attribution to the author(s) and the title of transitions starting from the same twofold degenerate ground state. 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.

Introduction

Experiment and modeling

Results

Discussion

Conclusion