Iotti Rita Claudia, Rossi Fausto
Department of Applied Science and Technology, Politecnico di Torino, Corso Duca degli Abruzzi 24, 10129 Torino, Italy.
Entropy (Basel). 2020 Apr 24;22(4):489. doi: 10.3390/e22040489.
The design and optimization of new-generation solid-state quantum hardware absolutely requires reliable dissipation versus decoherence models. Depending on the device operational condition, the latter may range from Markov-type schemes (both phenomenological- and microscopic- like) to quantum-kinetic approaches. The primary goal of this paper is to review in a cohesive way virtues versus limitations of the most popular approaches, focussing on a few critical issues recently pointed out (see, e.g., Phys. Rev. B , 125140 (2014); Eur. Phys. J. B , 250 (2017)) and linking them within a common framework. By means of properly designed simulated experiments of a prototypical quantum-dot nanostructure (described via a two-level electronic system coupled to a phonon bath), we shall show that both conventional (i.e., non-Lindblad) Markov models and density-matrix-based non-Markov approaches (i.e., quantum-kinetic treatments) may lead to significant positivity violations. While for the former case the problem is easily avoidable by choosing genuine Lindblad-type dissipation models, for the latter, a general strategy is still missing.
新一代固态量子硬件的设计与优化绝对需要可靠的耗散与退相干模型。根据设备的运行条件，后者的范围可能从马尔可夫型方案（包括唯象型和微观型）到量子动力学方法。本文的主要目标是以连贯的方式回顾最流行方法的优点与局限性，聚焦于最近指出的一些关键问题（例如，见《物理评论B》，125140 (2014); 《欧洲物理杂志B》，250 (2017)），并将它们置于一个共同框架内进行关联。通过对一个原型量子点纳米结构进行适当设计的模拟实验（通过一个与声子浴耦合的二能级电子系统来描述），我们将表明，传统的（即非林德布拉德型）马尔可夫模型和基于密度矩阵的非马尔可夫方法（即量子动力学处理）都可能导致显著的正定性破坏。虽然对于前一种情况，通过选择真正的林德布拉德型耗散模型很容易避免问题，但对于后一种情况，仍然缺少通用策略。
