Quench dynamics and statistics of measurements for a line of quantum spins in two dimensions

TL;DR

This paper studies the quench dynamics and measurement statistics of a line of spins in a 2D xxz model near the Ising limit, combining semiclassical approximations and recent measurement techniques.

Contribution

It introduces a semiclassical approach to analyze complex spin dynamics and predicts measurement statistics that reveal more information than traditional correlation functions.

Findings

Dynamics governed by 1D excitations and spin evaporation

Semiclassical approximation effectively models the system

Measurement statistics provide deeper insights into quantum states

Abstract

Motivated by recent experiments, we investigate the dynamics of a line of spin-down spins embedded in the ferromagnetic spin-up ground state of a two-dimensional xxz model close to the Ising limit. In a situation where the couplings in x and y direction are different, the quench dynamics of this system is governed by the interplay of one-dimensional excitations (kinks and holes) moving along the line and single-spin excitations evaporating into the two-dimensional background. A semiclassical approximation can be used to calculate the dynamics of this complex quantum system. Recently, it became possible to perform projective quantum measurements on such spin systems, allowing to determine, e.g., the z-component of each individual spin. We predict the statistical properties of such measurements which contain much more information than correlation functions.