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arXiv 2107.01075quant-phmath-phmath.MP
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马尔可夫玻色子环境中的量子演化速度

Quantum speed of evolution in a Markovian bosonic environment

Paulina Marian, Tudor A. Marian

摘要:

我们提出了明确的评估量子速度极限时间有关的马尔可夫动力学的开放连续变量系统。具体地说,我们考虑了弱耦合到热玻色子水库的量子辐射场的腔模式的标准设置。场态的演化由量子光学主方程决定,已知该主方程具有精确的解析解。从一个纯粹的输入状态,我们采用两个指标,如何不同的初始和演化状态,即演化的保真度和希尔伯特-施密特距离的演变。前者由del Campo { \em et al.}他推导出了马尔可夫开放系统演化的与时间无关的速度极限。我们评估它为这个领域的水库设置,与任意输入纯状态的字段模式。然后将所得公式专门用于相干态和Fock态。另一方面,我们利用一种替代方法,采用上述两个指标的演变。它们的变化率具有相同的上限,因此提供了一个独特的时间依赖的量子速度限制。结果表明,基于希尔伯特-施密特度规的量子速度极限时间比基于量子数的量子速度极限时间更紧.作为相应的应用,我们利用相应演化态的特征函数研究了相干态和Fock态的阻尼。得到了这两类输入态的演化保真度和Hilbert-Schmidt距离的一般表达式,并进行了分析。在相干态的情况下,我们导出了它们的共同速度极限和一对相关联的极限时间的精确公式。

英文摘要:

We present explicit evaluations of quantum speed limit times pertinent to the Markovian dynamics of an open continuous-variable system. Specifically, we consider the standard setting of a cavity mode of the quantum radiation field weakly coupled to a thermal bosonic reservoir. The evolution of the field state is ruled by the quantum optical master equation, which is known to have an exact analytic solution. Starting from a pure input state, we employ two indicators of how different the initial and evolved states are, namely, the fidelity of evolution and the Hilbert-Schmidt distance of evolution. The former was introduced by del Campo {\em et al.} who derived a time-independent speed limit for the evolution of a Markovian open system. We evaluate it for this field-reservoir setting, with an arbitrary input pure state of the field mode. The resultant formula is then specialized to the coherent and Fock states. On the other hand, we exploit an alternative approach that employs both indicators of evolution mentioned above. Their rates of change have the same upper bound, and consequently provide a unique time-dependent quantum speed limit. It turns out that the associate quantum speed limit time built with the Hilbert-Schmidt metric is tighter than the fidelity-based one. As apposite applications, we investigate the damping of the coherent and Fock states by using the characteristic functions of the corresponding evolved states. General expressions of both the fidelity and the Hilbert-Schmidt distance of evolution are obtained and analyzed for these two classes of input states. In the case of a coherent state, we derive accurate formulas for their common speed limit and the pair of associate limit times.

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