Optimal Squeezing in Resonance Fluorescence via Atomic-State Purification

TL;DR

This paper demonstrates that optimal squeezing of atomic resonance fluorescence can be achieved by designing an environment with a quasi-resonant cavity, which purifies the atomic state and enhances coherence, leading to reduced fragility of squeezing.

Contribution

It introduces a method to optimize atomic resonance fluorescence squeezing through atomic-state purification using cavity backaction, achieving high purity and robustness.

Findings

Atomic coherence maximization leads to optimal squeezing.

Cavity backaction purifies the atomic state to over 99%.

Fragility of squeezing against dephasing is significantly reduced.

Abstract

Squeezing of atomic resonance fluorescence is shown to be optimized by a properly designed environment, which can be realized by a quasi-resonant cavity. Optimal squeezing is achieved if the atomic coherence is maximized, corresponding to a pure atomic quantum state. The atomic-state purification is achieved by the backaction of the cavity field on the atom, which increases the atomic coherence and decreases the atomic excitation. For realistic cavities, the coupling of the atom to the cavity field yields a purity of the atomic state of more than 99%. The fragility of squeezing against dephasing is substantially reduced in this scenario, which may be important for various applications.