Engineering quantum criticality and dynamics on an analog-digital simulator

TL;DR

This paper demonstrates a hybrid analog-digital quantum simulation approach using neutral atoms to engineer and probe complex out-of-equilibrium many-body phenomena, including quantum spin liquids, with high control and measurement fidelity.

Contribution

It introduces a novel analog-digital simulation method combining coherent mapping, programmable control, and error mitigation to study complex quantum dynamics and critical states.

Findings

Successful simulation of ring-exchange and particle hopping dynamics.

Measurement of spectral functions of single excitations.

Observation of key features of a quantum spin liquid, including many-body coherences.

Abstract

Understanding emergent phenomena in out-of-equilibrium interacting many-body systems is an exciting frontier in physical science. While quantum simulators represent a promising approach to this long-standing problem, in practice it can be challenging to directly realize the required interactions, measure arbitrary observables, and mitigate errors. Here we use coherent mapping between the Rydberg and hyperfine qubits in a neutral atom array simulator to engineer and probe complex quantum dynamics. We combine efficient analog dynamics with fully programmable state preparation and measurement, leverage non-destructive readout for loss information and atomic qubit reuse, and use an atom reservoir for replacing lost atoms. With this analog-digital approach, we first demonstrate dynamical engineering of ring-exchange and particle hopping dynamics via Floquet driving and measure the spectral function of single excitations by evolving initial superposition states. Extending these techniques to a 271-site kagome lattice, we employ closed-loop optimization to target an out-of-equilibrium critical quantum spin liquid of the Rokhsar-Kivelson type. We observe the key features of such a state, including the absence of local order, many-body coherences between nearly equal-amplitude dimer configurations over up to 18 sites, and universal correlations consistent with predictions from field theory. Together, these results pave the way for using dynamical control in analog-digital quantum simulators to study complex quantum many-body systems.