Preparing spin-squeezed states in Rydberg atom arrays via quantum optimal control

Abstract: We present a quantum optimal control protocol to generate highly spin-squeezed states in Rydberg atom arrays coupled via Ising-type Van der Waals interactions. Using gradient-based optimization techniques we construct time-dependent pulse sequences that steer an initial product state toward highly entangled, spin-squeezed states with predefined magnetization and squeezing axes. We focus on the Wineland parameter $\xi_W^2$ to measure spin squeezing and our approach achieves near-optimal spin squeezing in one-dimensional ring arrays of up to $N=8$ spins, generating states with entanglement depths exceeding 6, and significantly outperforming conventional quench dynamics for all system sizes studied. Remarkably, optimized pulse sequences can be directly scaled to larger arrays without additional optimization, achieving a squeezing parameter as low as $\xi_W^2 = 0.227$ in systems containing $N=50$ spins. This work demonstrates the potential of quantum optimal control methods for preparing highly spin-squeezed states, opening pathways to enhanced quantum metrology.