Driven quadrature and spin squeezing in a cavity-coupled ensemble of two-level states

TL;DR

This paper theoretically investigates quadrature and spin squeezing in a driven cavity-ensemble system, revealing limits of squeezing and effects of dephasing, with potential applications in quantum information processing.

Contribution

It introduces a theoretical framework for analyzing quadrature and spin squeezing in a driven cavity-coupled ensemble, highlighting the effects of pure-dephasing and ensemble parameters.

Findings

Steady-state quadrature squeezing approaches -3 dB.

Frequency-modulated squeezing approaches -14 dB.

Spin-squeezed entanglement occurs with weak driving.

Abstract

The generated magnitude of quadrature squeezing in a cavity-coupled ensemble, which is continuously driven using a coherent off-axis field, is theoretically explored. Using a truncated set of equations-of-motion derived from a Dicke Hamiltonian, steady-state quadrature squeezing of the cavity field is numerically calculated to approach a limit of -3 dB, while frequency-modulated quadrature squeezing approaches a limit of -14 dB, in the absence of pure-dephasing, and as a function of the ensemble's size and detuning. The impact of pure-dephasing on steady-state quadrature squeezing is shown to be mitigated by increased detuning of the driving field, while frequency-modulated squeezing is only shielded in a regime where the cumulative coupling and driving rates are in excess of the pure-dephasing rate. Spin-squeezed entanglement is also calculated to occur simultaneously with weakly-driven frequency-modulated quadrature squeezing.