Entanglement with neutral atoms in the simulation of nonequilibrium dynamics of one-dimensional spin models

TL;DR

This paper explores how entanglement can be generated and utilized in neutral atom systems for quantum computation and simulation, demonstrating robust entangling gates and analyzing critical dynamics in spin models.

Contribution

It introduces a robust neutral atom Mølmer-Sørensen gate and applies matrix product states to study critical behavior in quantum spin dynamics.

Findings

The Mølmer-Sørensen gate shows robustness to experimental imperfections.

Order parameters and critical exponents can be estimated with modest computational resources.

Local observables in quenched dynamics are well approximated by low entanglement or near-maximally mixed states.

Abstract

Quantum entanglement is a key ingredient for quantum information processing with capabilities beyond that of classical computation. We study the generation and role of entanglement in the dynamics of spin-1/2 models, both for the design of quantum gates for general-purpose quantum computation and for quantum simulation of interacting spin models. We introduce the neutral atom M{\o}lmer-S{\o}rensen gate, involving rapid adiabatic Rydberg dressing interleaved in a spin-echo sequence. We show its robustness to quasi-static experimental imperfections and favorable scaling with the time-energy scales of Rydberg-mediated entanglement generation. In quantum simulation, we consider critical behavior in quench dynamics of transverse field Ising models. Using matrix product states to calculate the dynamics, we find that order parameters, critical point, and critical exponents can be estimated using modest bond dimensions. Considering the role of chaos and equilibration in quenches, we find that local observables are well approximated either due to low global entanglement or the proximity of local marginals to the maximally mixed state. These findings highlight the challenge of identifying relevant quantum phenomena that remain inaccessible to classical descriptions. Understanding the regimes where classical descriptions fail but remain accessible to pre-fault tolerant quantum hardware will help inform the design of future quantum information processors