Characterising quantum measurement through environmental stochastic entropy production in a two spin 1/2 system

Abstract

Quantum state diffusion is a framework within which measurement may be described as the continuous and gradual collapse of a quantum system to an eigenstate as a result of interaction with its environment. The irreversible nature of the quantum trajectories that arise may be characterised by the environmental stochastic entropy production associated with the measurement. We consider a system of two spin 1/2 particles undergoing either single particle measurements or measurements of the total z-spin component S_{z}. The mean asymptotic rates of environmental stochastic entropy production associated with collapse can depend on the eigenstate of S_{z} selected, and on the initial state of the system, offering an additional avenue for characterising quantum measurement.