Long-term behaviour in an exactly solvable model of pure decoherence and the problem of Markovian embedding

• URL: http://arxiv.org/abs/2311.16010v1
• Date: Mon, 27 Nov 2023 17:09:27 GMT
• Title: Long-term behaviour in an exactly solvable model of pure decoherence and the problem of Markovian embedding
• Authors: Anton Trushechkin
• Abstract summary: We consider a well-known exactly solvable model of an open quantum system with pure decoherence. It is worthwhile to study how the long-term rate of decoherence depends on the spectral density characterizing the system-bath interaction.
• Score: 0.0
• License: http://arxiv.org/licenses/nonexclusive-distrib/1.0/
• Abstract: We consider a well-known exactly solvable model of an open quantum system with pure decoherence. The aim of this paper is twofold. Firstly, decoherence is a property of open quantum systems important for both quantum technologies and the fundamental question of quantum-classical transition. It is worthwhile to study how the long-term rate of decoherence depends on the spectral density characterizing the system-bath interaction in this exactly solvable model. Secondly, we address a more general problem of the Markovian embedding of a non-Markovian open system dynamics. It is often assumed that a non-Markovian open quantum system can be embedded into a larger Markovian system. However, we show that such embedding is possible only for the Ohmic spectral densities (for the case of a positive bath temperature) and is impossible for both the sub- and super-Ohmic spectral densities. From the other side, for the Ohmic spectral densities, an asymptotic large-time Markovianity (in terms of the quantum regression formula) takes place.

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