Quantum quenches and driven dynamics in a single-molecule device
Quantum quenches and driven dynamics in a single-molecule device
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单分子装置中的量子猝灭和驱动动力学
DOI：
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发表时间：
2011
期刊：
影响因子：
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通讯作者：
N. Andrei
中科院分区：
文献类型：
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作者：
Yuval Vinkler;A. Schiller;N. Andrei
在单分子晶体管的一般模型的框架下，研究了分子器件的非平衡动力学：通过位移耦合到单个振动模的共振能级。在宽能级的限制下，在共振附近，模型可控制地约化为玻色算符的二次型，进而精确可解。因此，系统对一大类突然猝灭和交流驱动的响应是以非微扰方式计算的，从而在弱电-声子耦合极限下提供了渐近精确的解。从解析解，我们能够(1)明确地表明系统在局域量子失超后发生热化，(2)详细分析所涉及的时间尺度，(3)表明对量子失超的响应的驰豫时间取决于所讨论的可观测量，以及(4)揭示长时间振荡的幅度是如何随着交流驱动的频率在共振频率上被调谐而演变的。给出了所有物理量和所研究的所有非平衡情形的显式解析表达式。
The nonequilibrium dynamics of molecular devices is studied in the framework of a generic model for single-molecule transistors: a resonant level coupled by displacement to a single vibrational mode. In the limit of a broad level and in the vicinity of the resonance, the model can be controllably reduced to a form quadratic in bosonic operators, which in turn is exactly solvable. The response of the system to a broad class of sudden quenches and ac drives is thus computed in a nonperturbative manner, providing an asymptotically exact solution in the limit of weak electron-phonon coupling. From the analytic solution, we are able to (1) explicitly show that the system thermalizes following a local quantum quench, (2) analyze in detail the time scales involved, (3) show that the relaxation time in response to a quantum quench depends on the observable in question, and (4) reveal how the amplitude of long-time oscillations evolves as the frequency of an ac drive is tuned across the resonance frequency. Explicit analytical expressions are given for all physical quantities and all nonequilibrium scenarios under study.