Surprises in reservoir-engineering approaches to spin-squeezing*

Spin-squeezed states can be useful in metrological applications as they allow for sensing beyond the standard quantum limit. In recent years, a variety of mechanisms for generating such states have been proposed theoretically, as well as in some cases, realized experimentally. In this talk, we revisit the theory of dissipative protocols, where appropriately engineered noise processes can be utilized for spin-squeezing generation [1][2]. In the Markovian limit, we analyze the surprising consequences of single-spin dephasing and relaxation, and outline optimized mitigation strategies. We also analyze a non-Markovian regime directly relevant to realizations where an NV center spin ensemble is coupled to a mechanical mode.
[1] Agarwal and Puri, Phys. Rev. A 41, 3782 (1990).
[2] Dalla Torre, E. G., et al., Phys. Rev. Lett. 110, 120402 (2013)