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

TL;DR

This paper develops a quantum optimal control method to efficiently generate highly spin-squeezed states in Rydberg atom arrays, significantly improving squeezing performance over traditional methods and scalable to larger systems for quantum metrology.

Contribution

It introduces a gradient-based quantum optimal control protocol for creating highly entangled spin-squeezed states in Rydberg atom arrays, with scalable pulse sequences for larger systems.

Findings

Achieves near-optimal spin squeezing in small arrays.

Scalable pulse sequences produce strong squeezing in larger arrays.

Outperforms conventional quench dynamics across studied sizes.

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, 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.