一、 题目：Floquet response theory and spectroscopy: exotic stationary states, dark states, quantum light, and comparison to the standard nonlinear response theory

二、 主讲人：G. Engelhardt

三、 时间：2020年10月15日（周四），下午14:30

四、 地点：闻理园 A4-218

摘要: In the recent decades, the light-matter interaction could be pushed to the strong coupling regime in different experimental platforms, such as superconducting qubits, cold atoms in optical cavities, and molecules in polaritonic cavities. This opens up new chances for the quantum control, but imposes also theoretical challenges. Recently, Floquet response theory has been developed to describe quantum systems which are subject to a possible strong, but periodic driving field, and a weak, but arbitrary probe field.

In this talk, we explain how to treat spectroscopy of strongly-driven quantum system based on the input-output theory and the Floquet response theory, such that distinct optical effects can be described on equal footing. In this context, we address several important findings:

(i) The investigation of stationary states of periodically-driven quantum systems shows that they can strongly deviate from the so-called Floquet-Gibbs ensembles and can exhibit exotic non-analytic behavior which is visible in the emission [1]; (ii) The study of dynamically-generalized symmetries demonstrate the appearance of dark-states and selection rules for inelastically scattered light; (iii) The generation of squeezed and entangled light is possible by a device of sequentially-coupled strongly-driven quantum systems, which are described by the Floquet response theory; (iv) A comparison of Floquet response theory and the standard nonlinear response theory shows that both frameworks are not equivalent.

参考文献

[1] G. Engelhardt, G. Platero, and J. Cao, Phys. Rev. Lett. 123, 120602 (2019)

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