Local arrows of time in quantum many-body systems

TL;DR

This paper explores how local arrows of time in quantum many-body systems can differ from the global time, showing that local perceptions of time can vary within the same system due to quantum effects.

Contribution

It introduces a formal definition of local arrows of time in quantum many-body systems and analyzes their relation to spacetime quantum entropies with diverse examples.

Findings

Local arrows of time can differ across subsystems within the same quantum system.

Quantum thermalization and error correction can give rise to exotic local arrows of time.

Numerical and analytical models demonstrate the variability of local time flow.

Abstract

We demonstrate that in quantum many-body systems, local arrows of time can differ from the global time $t$ induced by Hamiltonian evolution. That is, within a quantum many-body system, the flow of time can be relative to each observer or by proxy each local subsystem. We provide a definition of local arrows of time in quantum many-body systems, and explain their relation to spacetime quantum entropies. Then we give a variety of numerical and analytical examples which explore different ways in which local arrows of time can manifest in quantum many-body dynamics, including exotic arrows of time arising from quantum thermalization and quantum error correction.