Real-time dynamics of string breaking in quantum spin chains

TL;DR

This paper investigates the real-time process of string breaking in quantum spin chains, revealing a two-stage dynamical process with significant dependence on initial conditions, and discusses experimental realizations.

Contribution

It introduces a novel effective description of string breaking dynamics in quantum Ising chains with confinement, highlighting a two-stage process and the impact of initial separation.

Findings

String breaking occurs as a two-stage process with a delayed final break.

The time scale for string breaking depends strongly on initial domain wall separation.

Experimental setups like Rydberg atoms can observe these dynamics.

Abstract

String breaking is a central dynamical process in theories featuring confinement, where a string connecting two charges decays at the expense of the creation of new particle-antiparticle pairs. Here, we show that this process can also be observed in quantum Ising chains where domain walls get confined either by a symmetry-breaking field or by long-range interactions. We find that string breaking occurs, in general, as a two-stage process: First, the initial charges remain essentially static and stable. The connecting string, however, can become a dynamical object. We develop an effective description of this motion, which we find is strongly constrained. In the second stage, which can be severely delayed due to these dynamical constraints, the string finally breaks. We observe that the associated time scale can depend crucially on the initial separation between domain walls and can grow by orders of magnitude by changing the distance by just a few lattice sites. We discuss how our results generalize to one-dimensional confining gauge theories and how they can be made accessible in quantum simulator experiments such as Rydberg atoms or trapped ions.