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arXiv 1806.09358cond-mat.stat-mech
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准周期驱动量子系统的渐近理论

Asymptotic theory of quasiperiodically driven quantum systems

David Cubero, Ferruccio Renzoni

摘要:

准周期驱动量子系统的理论处理由于Floquet定理的不适用性而变得复杂,Floquet定理需要严格的周期性。在这项工作中,我们考虑了一个量子系统驱动的双谐波驱动,并检查其渐近长时间的限制,在该限制中的功能区分系统与周期和准周期驱动发生。此外,在经典的情况下,这种限制是已知的表现出普遍的缩放,独立于系统的细节,与系统的响应下的准周期驱动被描述在附近的周期性驱动的系统结果。我们引入了一个理论框架,适合于治疗的准周期驱动的量子系统在长时间的限制,并推导出一个表达式,基于Floquet状态的周期驱动系统近似的不同步骤的时间演化,为系统的相关量的渐近标度在手。这些表达式进行了数值测试,发现在一个典型的量子棘轮组成的空间对称的潜力和时间不对称的振荡力的有限时间平均速度非常一致。

英文摘要:

The theoretical treatment of quasi-periodically driven quantum systems is complicated by the inapplicability of the Floquet theorem, which requires strict periodicity. In this work we consider a quantum system driven by a bi-harmonic driving and examine its asymptotic long-time limit, the limit in which features distinguishing systems with periodic and quasi-periodic driving occur. Also, in the classical case this limit is known to exhibit universal scaling, independent of the system details, with the system's reponse under quasi-periodic driving being described in terms of nearby periodically driven system results. We introduce a theoretical framework appropriate for the treatment of the quasi-periodically driven quantum system in the long-time limit, and derive an expression, based on Floquet states for a periodically driven system approximating the different steps of the time evolution, for the asymptotic scaling of relevant quantities for the system at hand. These expressions are tested numerically, finding excellent agreement for the finite-time average velocity in a prototypical quantum ratchet consisting of a space-symmetric potential and a time-asymmetric oscillating force.

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