Quantum trajectories for environment in superposition of coherent states

TL;DR

This paper develops stochastic master equations describing the conditional evolution of a quantum system interacting with a Bose field in a superposition of coherent states, using a collision model with an entangled environment chain.

Contribution

It introduces a novel collision model approach to derive stochastic master equations for systems coupled to superposed coherent state environments.

Findings

Derived stochastic master equations for counting and diffusive processes.

Established a limit of discrete recurrence equations for continuous observation.

Demonstrated the model's applicability to quantum systems in superposition states.

Abstract

We derive stochastic master equations for a quantum system interacting with a Bose field prepared in a superposition of continuous-mode coherent states. To determine a conditional evolution of the quantum system we use a collision model with an environment given as an infinite chain of not interacting between themselves qubits prepared initially in a entangled state being a discrete analogue of a superposition of coherent states of the Bose field. The elements of the environment chain interact with the quantum system in turn one by one and they are subsequently measured. We determine a conditional evolution of the quantum system for continuous in time observations of the output field as a limit of discrete recurrence equations. We consider the stochastic master equations for a counting as well as for a diffusive stochastic process.