A Rydberg Programmable Quantum Simulator with 256 Qubits

The realization of programmable quantum many-body systems capable of coherently controlling hundreds of individual particles is one of the frontiers of quantum science and engineering. Such systems provide unique insights into exotic quantum states of matter and enable new approaches to quantum computation. Our platform at Harvard consists of 2D arrays of laser-cooled neutral atoms trapped in optical tweezers. Using coherent coupling to highly-excited Rydberg states, we realize a quantum spin model with tunable long-range interactions for system sizes up to 256 qubits. With this platform, we have recently realized high-fidelity antiferromagnetically ordered states, mapped out the square-lattice phase diagram, and demonstrated the universal properties of an Ising quantum phase transition in (2+1) dimensions. Separately, we have also observed non-equilibrium quantum many-body scar dynamics after rapid quenches of 2D antiferromagnetically ordered states, and showed that these scars can be stabilized by periodic driving that generates a robust sub-harmonic response akin to discrete time-crystalline order. Ongoing efforts include quantum optimization of graph problems that can be encoded efficiently in our system, and realizing exotic entangled states of matter on frustrated lattices.