Dynamics of charge fluctuations from asymmetric initial states

TL;DR

This paper investigates how charge fluctuations evolve in quantum many-body systems starting from charge-asymmetric initial states, revealing effective inhomogeneities and providing explicit predictions for integrable systems using advanced theoretical methods.

Contribution

It introduces a novel analysis of charge fluctuations from asymmetric initial states, combining space-time duality and generalized hydrodynamics for integrable systems.

Findings

Charge fluctuations induce effective inhomogeneity in initially homogeneous states.

Mapping to inhomogeneous, charge-symmetric states simplifies analysis.

Explicit predictions for charge dynamics in integrable models.

Abstract

Conserved-charge densities are very special observables in quantum many-body systems as, by construction, they encode information about the dynamics. Therefore, their evolution is expected to be of much simpler interpretation than that of generic observables and to return universal information on the state of the system at any given time. Here we study the dynamics of the fluctuations of conserved U(1) charges in systems that are prepared in charge-asymmetric initial states. We characterise the charge fluctuations in a given subsystem using the full-counting statistics of the truncated charge and the quantum entanglement between the subsystem and the rest resolved to the symmetry sectors of the charge. We show that, even though the initial states considered are homogeneous in space, the charge fluctuations generate an effective inhomogeneity due to the charge-asymmetric nature of the initial states. We use this observation to map the problem into that of charge fluctuations on inhomogeneous, charge-symmetric states and treat it using a recently developed space-time duality approach. Specialising the treatment to interacting integrable systems we combine the space-time duality approach with generalised hydrodynamics to find explicit predictions.