Parametrization and optimization of Gaussian non-Markovian unravelings for open quantum dynamics

TL;DR

This paper develops a family of Gaussian non-Markovian stochastic Schrödinger equations for open quantum systems, enabling tailored measurement schemes and optimized quantum information processing in non-Markovian environments.

Contribution

It introduces a parametrized class of unravelings with measurement interpretations and noise correlations, independent of squeezing parameters, for improved quantum information tasks.

Findings

Derived a family of Gaussian non-Markovian stochastic equations

Provided measurement interpretations for different unravelings

Optimized squeezing parameters for entanglement tasks

Abstract

We derive a family of Gaussian non-Markovian stochastic Schr\"odinger equations for the dynamics of open quantum systems. The different unravelings correspond to different choices of squeezed coherent states, reflecting different measurement schemes on the environment. Consequently, we are able to give a single shot measurement interpretation for the stochastic states and microscopic expressions for the noise correlations of the Gaussian process. By construction, the reduced dynamics of the open system does not depend on the squeezing parameters. They determine the non-hermitian Gaussian correlation, a wide range of which are compatible with the Markov limit. We demonstrate the versatility of our results for quantum information tasks in the non-Markovian regime. In particular, by optimizing the squeezing parameters, we can tailor unravelings for optimal entanglement bounds or for environment-assisted entanglement protection.