The Schr\"{o}dinger equation for open systems

TL;DR

This paper introduces an exact framework for describing open quantum systems using stochastic Schr"odinger equations, demonstrating that their evolution is unitary on average and confirming the optical theorem for inelastic scattering.

Contribution

It proposes a universal stochastic Schr"odinger equation approach for open quantum systems, providing a new exact description of their kinetics.

Findings

Evolution of random quantum states is unitary on average

Validates the optical theorem for inelastic scattering

Provides a universal exact description of open system dynamics

Abstract

An universal exact description of kinetics of open quantum systems in terms of random wave functions and stochastic Schr\"{o}dinger equation is suggested. It is shown that evolution of random quantum states of an open system is unitary on average, and this implies validity of the optical theorem for any inelastic scattering.