Ballistic propagation of a local impact in the one-dimensional $XY$ model

Abstract

Light-cone-like propagation of information is a universal phenomenon of nonequilibrium dynamics of integrable spin systems. In this paper, we investigate propagation of a local impact in the one-dimensional $XY$ model with the anisotropy $\gamma$ in a magnetic field $h$ by calculating the magnetization profile. Applying a local and instantaneous unitary operation to the ground state, which we refer to as the local-impact protocol, we numerically observe various types of light-cone-like propagation in the parameter region $0\le \gamma \le 1$ and $0\le h\le 2$ of the model. By combining numerical integration with an asymptotic analysis, we find the following: (i) for $|h|\ge |1-{\gamma }^2|$ except for the case on the line $h=1$ with $0<\gamma <\sqrt{3}/2$, a wave front propagates with the maximum group velocity of quasiparticles, except for the case $\gamma =1$ and $0<h<1$, in which there is no clear wave front; (ii) for $|h|<|1-{\gamma }^2|$ as well as on the line $h=1$ with $0<\gamma <\sqrt{3}/2$, a second wave front appears owing to multiple local extrema of the group velocity; (iii) for $|h|=|1-{\gamma }^2|$, edges of the second wave front collapses at the origin, and as a result, the magnetization profile exhibits a ridge at the impacted site. Furthermore, we find by an asymptotic analysis that the height of the wave front decays in a power law in time $t$ with various exponents depending on the model parameters: the wave fronts exhibit a power-law decay $t^{-2/3}$ except for the line $h=1$, on which the decay can be given by either $\sim t^{-3/5}$ or $\sim t^{-1}$; the ridge at the impacted site for $|h|=|1-{\gamma }^2|$ shows the decay $t^{-1/2}$ as opposed to the decay $t^{-1}$ in other cases.

29 pages, 9 figures; version 4: typos collected. Published in J. Stat. Mech

References in corpus (17)

• Many-Body Physics with Ultracold Gases
• Thermalization and its mechanism for generic isolated quantum systems
• Many body localization and thermalization in quantum statistical mechanics
• Lieb-Robinson bounds and the generation of correlations and topological quantum order
• Lieb-Robinson Bounds and the Exponential Clustering Theorem
• Evolution of entanglement entropy following a quantum quench: Analytic results for the XY chain in a transverse magnetic field
• Proof of the Ergodic Theorem and the H-Theorem in Quantum Mechanics
• "Light-cone" dynamics after quantum quenches in spin chains
• Propagation of Correlations in Quantum Lattice Systems
• Transport in out-of-equilibrium XXZ chains: non-ballistic behavior and correlation functions
• Full counting statistics in a propagating quantum front and random matrix spectra
• Quantum phase transition in a far from equilibrium steady state of XY spin chain
• Thermalization and light cones in a model with weak integrability breaking
• Charges and currents in quantum spin chains: late-time dynamics and spontaneous currents
• Approximate light cone effects in a non-relativistic quantum field theory after a local quench
• Quantum dimensions from local operator excitations in the Ising model
• Classical Lieb-Robinson Bound for Estimating Equilibration Timescales of Isolated Quantum Systems

Cited by in corpus (1)

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