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arXiv 2001.11948quant-phmath-phmath.MP
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局部和非局部主方程之间的相互作用:精确和近似动力学

The interplay between local and non-local master equations: exact and approximated dynamics

Nina Megier, Andrea Smirne, Bassano Vacchini

摘要:

主方程是描述开放量子系统演化的有效工具。为了刻画动力学的数学特征和物理根源,通常需要考虑同一系统的不同类型的主方程。在这里,我们推导出一个精确的时间本地和积分微分描述之间的连接,专注于类交换动力学。阻尼基形式主义的使用使我们能够设计一个一般的程序,从一个主方程到另一个,反之亦然,通过只处理时间函数及其拉普拉斯变换。我们进一步分析了Lindbladian形式的时间局部和积分微分主方程,在那里我们占不同的Lindbladian运营商的外观。此外,我们还研究了Redfield近似,它通过时间粗粒化将精确的积分微分方程转化为时间局部方程。除了与所得到的主方程的结构与精确的动力学,我们研究的近似Markovianity的影响。特别是,我们表明,与预期相反,粗粒化的时间可能会引入记忆效应,导致违反整除性质的动态。

英文摘要:

Master equations are a useful tool to describe the evolution of open quantum systems. In order to characterize the mathematical features and the physical origin of the dynamics, it is often useful to consider different kinds of master equations for the same system. Here, we derive an exact connection between the time-local and the integro-differential descriptions, focusing on the class of commutative dynamics. The use of the damping-basis formalism allows us to devise a general procedure to go from one master equation to the other and vice-versa, by working with functions of time and their Laplace transforms only. We further analyze the Lindbladian form of the time-local and the integro-differential master equations, where we account for the appearance of different sets of Lindbladian operators. In addition, we investigate a Redfield-like approximation, that transforms the exact integro-differential equation into a time-local one by means of a coarse graining in time. Besides relating the structure of the resulting master equation to those associated with the exact dynamics, we study the effects of the approximation on Markovianity. In particular, we show that, against expectation, the coarse graining in time can possibly introduce memory effects, leading to a violation of a divisibility property of the dynamics.

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