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arXiv 1302.4669quant-phcond-mat.other
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量子首次通过时间:一类紧束缚哈密顿系统的精确解

Quantum First-Passage Time: Exact Solutions for a Class of Tight-Binding Hamiltonian Systems

Ranjith V., N. Kumar

摘要:

将计算经典首达时间概率密度的薛定谔积分方程方法推广到量子首达时间概率密度的情形。利用这一推广,我们解析地计算了一类少位态紧束缚哈密顿系统的Q-fpt概率密度,例如,一个量子比特,以及一个无限的一维晶格。这种量子系统的定义特征是,穿过子空间(Ω)和它的补子空间(Ω-bar)之间的边界的通道是通过一对独特的“门口”位置,使得第一次离开(到达)Ω对应于第一次到达(离开)Ω-bar。由此导出的Q-fpt概率密度在其也归一化为1的时间间隔上保持为正。这些正性和归一化条件定义了Q-fpt问题的物理时域。这个时间域被发现保持有限的几个站点/状态的哈密顿系统在这里考虑,这是完全不同的情况下,扩散C-FPT问题。门口网站和相关的Q-FPT概率密度在这里得到的应该是相关的生物分子/纳米结构间的电子输运现象。

英文摘要:

The Schrödinger integral-equation approach for calculating the classical first-passage time (C-fpt) probability density is extended to the case of quantum first-passage time (Q-fpt). Using this extension, we have calculated analytically the Q-fpt probability density for a class of few-site/state tight-binding Hamiltonian systems, e.g., a qubit, as well as for an infinite 1D lattice. The defining feature of such a quantum system is that the passage across the boundary between a subspace (omega) and its complement (omega-bar) is through a unique pair of "door-way" sites such that the first departure from (arrival at) omega corresponds to the first arrival at (departure from) omega-bar. The Q-fpt probability density so derived remains positive over the time interval in which it also normalizes to unity. These conditions of positivity and normalization define the physical time domain for the Q-fpt problem. This time domain is found to remain finite for the few-site/state Hamiltonian systems considered here, which is quite unlike the case for the diffusive C-fpt problems. The door-way sites and the associated Q-fpt probability density derived here should be relevant to inter-biomolecular/nanostructural electron transport phenomena.

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