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arXiv · 2007.03234

A discrete memory-kernel for multi-time correlations in non-Markovian quantum processes

Mathias R. Jørgensen·Felix A. Pollock
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Abstract

Efficient simulations of the dynamics of open systems is of wide importance for quantum science and tech-nology. Here, we introduce a generalization of the transfer-tensor, or discrete-time memory kernel, formalism to multi-time measurement scenarios. The transfer-tensor method sets out to compute the state of an open few-body quantum system at long times, given that only short-time system trajectories are available. Here, we showthat the transfer-tensor method can be extended to processes which include multiple interrogations (e.g. measurements) of the open system dynamics as it evolves, allowing us to propagate high order short-time correlation functions to later times, without further recourse to the underlying system-environment evolution. Our approach exploits the process-tensor description of open quantum processes to represent and propagate the dynamics in terms of an object from which any multi-time correlation can be extracted. As an illustration of the utility of the method, we study the build-up of system-environment correlations in the paradigmatic spin-boson model, and compute steady-state emission spectra, taking fully into account system-environment correlations present in the steady state.

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Mathias R. Jørgensen, Felix A. Pollock. 2020-11-06. A discrete memory-kernel for multi-time correlations in non-Markovian quantum processes. https://doi.org/10.1103/physreva.102.052206

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