Decoherence and equilibration under nondestructive measurements

TL;DR

This paper investigates how nondestructive measurements influence decoherence and equilibration in finite quantum systems, showing that measurement type and frequency determine the extent of decoherence and the nature of equilibrium states.

Contribution

It provides a detailed analysis of how different measurement regimes induce decoherence and equilibration, highlighting the role of measurement frequency and type in quantum system dynamics.

Findings

Finite measurements cause partial decoherence

Infinite measurements lead to complete decoherence

Continuous measurements result in asymptotic equilibration

Abstract

The evolution of observable quantities of finite quantum systems is analyzed when the latter are subject to nondestructive measurements. The type and number of measurements characterize the level of decoherence produced in the system. A finite number of instantaneous measurements leads to only a partial decoherence. But infinite number of such measurements yields complete decoherence and equilibration. Continuous measurements result in partial decoherence in finite time, but produce complete decoherence and equilibration as time tends to infinity. Resulting equilibrium states are characterized by representative statistical ensembles that, generally, retain information on initial conditions. Any system, to be observable, necessarily requires the presence of measurements, whose large number leads to the system equilibration and decoherence.