Upper Bounds for the Poincar\'e Recurrence Time in Quantum Mixed States

TL;DR

This paper establishes upper bounds for the Poincaré recurrence time in quantum mixed states using geometric methods, considering both finite and infinite discrete spectra, with implications for quantum and classical recurrence processes.

Contribution

It introduces novel upper bounds for quantum recurrence times based on energy uncertainty and the number of relevant states, applicable to both finite and infinite spectra.

Findings

Derived bounds depend on energy uncertainty and state count.

Bound for finite spectrum relates to quantum recurrence time.

Bound for infinite spectrum connects to classical limit behavior.

Abstract

In this paper by using geometric techniques, we provide upper bounds for the Poincar\'e recurrence time of a quantum mixed state with discrete spectrum of energies. In the case of discrete but finite spectrum we obtain two type of upper bounds; one of them depends on the uncertainty in the energy, and the other depends only on the (finite) number of states. In the case of discrete but non-finite spectrum we obtain in the same way two upper bounds defining the number of relevant states according to an statistical measurement. These bounds correspond to two different situations in the quantum recurrence process. The first bound is a recurrence time estimation purely quantum, while the other bound that is related with the number of relevant states survives in the classical limit.