Ashida Yuto, İmamoğlu Ataç, Demler Eugene
Department of Physics, University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-0033, Japan.
Institute for Physics of Intelligence, University of Tokyo, 7-3-1 Hongo, Tokyo 113-0033, Japan.
Phys Rev Lett. 2021 Apr 16;126(15):153603. doi: 10.1103/PhysRevLett.126.153603.
Quantum light-matter systems at strong coupling are notoriously challenging to analyze due to the need to include states with many excitations in every coupled mode. We propose a nonperturbative approach to analyze light-matter correlations at all interaction strengths. The key element of our approach is a unitary transformation that achieves asymptotic decoupling of light and matter degrees of freedom in the limit where light-matter interaction becomes the dominant energy scale. In the transformed frame, truncation of the matter or photon Hilbert space is increasingly well justified at larger coupling, enabling one to systematically derive low-energy effective models, such as tight-binding Hamiltonians. We demonstrate the versatility of our approach by applying it to concrete models relevant to electrons in crystal potential and electric dipoles interacting with a cavity mode. A generalization to the case of spatially varying electromagnetic modes is also discussed.
由于需要在每个耦合模式中包含具有多个激发的态，强耦合下的量子光与物质系统的分析极具挑战性。我们提出一种非微扰方法来分析所有相互作用强度下的光与物质关联。我们方法的关键要素是一种幺正变换，它在光与物质相互作用成为主导能量尺度的极限情况下，实现光和物质自由度的渐近解耦。在变换后的框架中，在更大耦合下对物质或光子希尔伯特空间进行截断越来越合理，这使得人们能够系统地推导低能有效模型，如紧束缚哈密顿量。我们通过将其应用于与晶体势中的电子以及与腔模相互作用的电偶极子相关的具体模型，展示了我们方法的通用性。还讨论了对空间变化电磁模式情况的推广。
