Enhancing spin squeezing using soft-core interactions

We propose a protocol for preparing spin squeezed states in controllable atomic, molecular, and optical systems, with particular relevance to emerging optical clock platforms compatible with Rydberg interactions. By combining a short-range, soft-core potential with an external drive, we can transform naturally emerging Ising interactions into an XX spin model while opening a many-body gap. The gap helps maintain the system within a collective manifold of states where metrologically useful spin squeezing can be generated. We examine the robustness of our protocol to experimentally relevant decoherence and show favorable performance over typical protocols lacking gap protection. For example, in a 14 x 14 system, we observe that soft-core interactions can generate spin squeezing comparable to an all-to-all Ising model even in the presence of relevant decoherence, the same amount of squeezing as the decoherence-free XX spin model with 1/r3 dipolar interactions, and a 5.8 dB gain over the decoherence-free XX spin model with 1/r6 interactions.