An intrinsic limit to quantum coherence due to spontaneous symmetry breaking

TL;DR

This paper demonstrates that spontaneous symmetry breaking imposes a fundamental, universal limit on the duration of quantum coherence in macroscopic systems, depending on system size and temperature.

Contribution

It introduces an exactly solvable model showing how spontaneous symmetry breaking sets a universal timescale for quantum decoherence.

Findings

Quantum coherence is limited by a universal timescale $t_{spon}$.

The timescale depends on system size, temperature, and fundamental constants.

Spontaneous symmetry breaking fundamentally constrains quantum coherence in macroscopic systems.

Abstract

We investigate the influence of spontaneous symmetry breaking on the decoherence of a many-particle quantum system. This decoherence process is analyzed in an exactly solvable model system that is known to be representative of symmetry broken macroscopic systems in equilibrium. It is shown that spontaneous symmetry breaking imposes a fundamental limit to the time that a system can stay quantum coherent. This universal timescale is $t_{spon} \simeq 2\pi N \hbar / (k_B T)$, given in terms of the number of microscopic degrees of freedom $N$, temperature $T$, and the constants of Planck ($\hbar$) and Boltzmann ($k_B$).