Quantum quenches and work distributions in ultra-low-density systems

TL;DR

This paper investigates quantum quenches in low-density systems, revealing unique non-equilibrium behaviors such as non-thermalization and large edge singularities, differing from traditional thermodynamic limit expectations.

Contribution

It demonstrates that low-density quantum systems exhibit distinct quench dynamics, including non-thermalization and enhanced edge singularities, expanding understanding beyond standard thermodynamic assumptions.

Findings

Local quenches may not lead to equilibration in low-density systems.

Global quenches can produce power-law work distributions with large exponents.

Observable consequences include a unique intermediate power-law regime in time.

Abstract

We present results on quantum quenches in systems with a fixed number of particles in a large region. We show that the typical differences between local and global quenches present in systems with regular thermodynamic limit are lacking in this low-density limit. In particular, we show that in this limit local quenches may not lead to equilibration to the new ground state, and that global quenches can have power-law work distributions ("edge singularities") typically associated with local quenches for finite-density systems. We also show that this regime allows for large edge singularity exponents beyond that allowed by the constraints of the usual thermodynamic limit. This large-exponent singularity has observable consequences in the time evolution, leading to a distinct intermediate power-law regime in time. We demonstrate these results first using local quantum quenches in a low-density Kondo-like system, and additionally through global and local quenches in Bose-Hubbard, Aubry-Andre, and hard-core boson systems in the low-density regime.