Spin-squeezing using optimized parametric driving*

Spin-squeezed states are desirable for meteorological applications as they allow for sensing beyond the standard quantum limit. A variety of mechanisms for generating such states have been proposed theoretically, and in some cases, realized experimentally. Nevertheless, approaches that reach the Heisenberg-limited scaling (eg. 'two-axis twist') often require elaborate experimental setups, making them difficult to realize in practice, while ones that are more experimentally viable, (eg. 'one-axis-twist') have sub-optimal scaling. In this talk we consider a parametrically driven cavity, coupled to a spin ensemble. We show that a careful control of the parametric drive detuning and amplitude can let one achieve Heisenberg-limited scaling. We also discuss the impact of dissipation on performance. Our approach is general enough to be experimentally viable in a variety of systems including spin ensembles coupled to superconducting microwave cavities (e.g. [1]), but also spins that are strain-coupled to a nanomechanical resonator (e.g. [2,3]).

[1] Bienfait, A., et al., PRX 7.4, 041011 (2017)
[2] Bennett, S. D., et al., PRL 110.15, 156402 (2013)
[3] Lee, D., et al., J. of Opt. 19.3, 033001 (2017)