报告题目：(Quantum) Light Control of Quantum Materials

报 告 人：Dante M. Kennes, RWTH Aachen University

报告时间：2025年7月8日下午4点

报告地点：物理楼W105

报告摘要：Driving quantum materials is a promising route for potential future applications in the engineering of quantum properties, such as superconductivity and topologically protected edge states [1]. First, we are going to discuss some examples of how to control superconducting properties in ultrafast transient phenomena [2] by the transient steering of symmetries. Then we will switch gears and discuss potential routes to manipulate quantum properties in the emerging field of cavity quantum electrodynamics. The latter aims at controlling material properties via the coupling with the quantized photon modes in a cavity. Through the hybridization of light and matter we explore to which extent it is possible to tailor properties of extended solids, realizing what was coined “cavity quantum materials”[3, 4].

The entanglement entropy between light and matter is a direct measure of the degree of hybridization, but a clear understanding on what are the necessary conditions for this to be generated in the emergent field of cavity coupled band electrons [5, 6, 7] is still missing. We consider a paradigmatic model of interacting spinless fermions coupled with the first resonant mode of a cavity. We derive an analytic expression, exact in the cavity high frequency limit, that relates the cavity-matter entanglement to the quantum fluctuations of the current operator. This relation establishes that the presence of such fluctuations is a necessary condition for non-zero light-matter entanglement. Furthermore, we solve numerically exactly the model, showing that the qualitative behavior predicted by our analytic expansion holds in a wide range of parameters. We also discuss problematic aspects of mean field approaches to this model.

The results presented in this work are expected to hold in more general settings than the particular model discussed, providing a first fundamental condition for the realization of true light-matter hybridized band electrons in a cavity [8].

References:

[1] A. de la Torre et al, Rev. Mod. Phys. 93, 041002 (2021).

[2] M. Claassen et al, Nat. Phys. 15, 766-770 (2019).

[3] F. Schlawin et al, Applied Physics Reviews 9, 011312 (2022).

[4] A. Frisk Kockum et al, Nat Rev Phys 1, 19 (2019).

[5] F. Schlawin et al, Phys. Rev. Lett. 122, 133602 (2019).

[6] H. Gao et al, Phys. Rev. Lett. 125, 053602 (2020).

[7] A. Chakraborty et al, Phys. Rev. Lett. 127, 177002 (2021).

[8] G. Passetti et al, Phys. Rev. Lett. 131, 023601 (2023)

报告人简介：Dante M. Kennes is a professor at the RWTH Aachen University and visiting scientist at the Max Planck Institute for the Structure and Dynamics of Matter. His research focus lies on the theoretical study of ultrafast quantum materials design, non-equilibrium quantum many-body dynamics, and twisted van der Waals heterostructures. He uses renormalization group- or tensor network-based methods applicable to the equilibrium as well as out-of-equilibrium realm of strongly correlated systems. His research aims to realize quantum materials with specific tailored properties enabling novel quantum functionalities.