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

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.

Automated summary

This study theoretically explores the magnitude of quadrature squeezing in a cavity-coupled ensemble driven by a coherent off-axis field. Numerical calculations show that steady-state quadrature squeezing approaches a limit of -3 dB, while frequency-modulated quadrature squeezing approaches a limit of -14 dB, in different conditions. The impact of pure dephasing can be mitigated by increasing the detuning of the driving field, and frequency-modulated squeezing is only shielded under specific conditions.