Unraveling the Excitation Spectrum of Many-Body Systems from Quantum Quenches

TL;DR

This paper demonstrates that the full low-lying excitation spectrum of many-body quantum systems can be extracted from quench dynamics of equal-time correlators, offering an alternative to traditional spectroscopic methods.

Contribution

It introduces a novel method to determine the excitation spectrum from quench dynamics, applicable to various models and higher dimensions, expanding the tools for quantum system analysis.

Findings

Successfully applied to 1D lattice models including Bose and spin systems

Applicable to higher dimensions, fermions, and continuous models

Provides an alternative to pump-probe spectroscopy

Abstract

Quenches are now routinely used in synthetic quantum systems to study a variety of fundamental effects, including ergodicity breaking, light-cone-like spreading of information, and dynamical phase transitions. It was shown recently that the dynamics of equal-time correlators may be related to ground-state phase transitions and some properties of the system excitations. Here, we show that the full low-lying excitation spectrum of a generic many-body quantum system can be extracted from the after-quench dynamics of equal-time correlators. We demonstrate it for a variety of one-dimensional lattice models amenable to exact numerical calculations, including Bose and spin models, with short- or long-range interactions. The approach also applies to higher dimensions, correlated fermions, and continuous models. We argue that it provides an alternative approach to standard pump-probe spectroscopic methods and discuss its advantages.