Control relaxation via dephasing: an exact quantum state diffusion study

TL;DR

This paper investigates how combining relaxation and dephasing noise channels can lead to novel quantum control strategies, showing that Markovian dephasing can suppress non-Markovian relaxation in atomic systems, offering new noise mitigation methods.

Contribution

It introduces an exact quantum state diffusion approach to study mixed relaxation and dephasing channels, revealing that dephasing can suppress relaxation, which is a novel control strategy in quantum systems.

Findings

Non-Markovian relaxation can be suppressed by Markovian dephasing.

Coordination of relaxation and dephasing leads to anomalous control strategies.

The approach provides a noise control method without artificial manipulation.

Abstract

Dynamical decoupling as a quantum control strategy aims at suppressing quantum decoherence adopting the popular philosophy that the disorder in the unitary evolution of the open quantum system caused by environmental noises should be neutralized by a sequence of ordered or well-designed external operations acting on the system. This work studies the solution of quantum-state-diffusion equations by mixing two channels of environmental noises, i.e., relaxation (dissipation) and dephasing. It is interesting to find in two-level and three-level atomic systems that a non-Markovian relaxation or dissipation process can be suppressed by a Markovian dephasing noise. The discovery results in an anomalous control strategy by coordinating relaxation and dephasing processes. Our approach opens an avenue of noise control strategy with no artificial manipulation over the open quantum systems.