Hannover 2020 – scientific programme

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Q: Fachverband Quantenoptik und Photonik

Q 60: Quantum Effects (Cavity QED)

Q 60.1: Talk

Friday, March 13, 2020, 11:00–11:15, f442

Ab initio few-mode theory — •Dominik Lentrodt and Jörg Evers — Max-Planck-Institut für Kernphysik, Heidelberg, Germany

Few-mode models, such as the Jaynes-Cummings model and its many generalizations, have been an indispensable tool in studying the quantum dynamics of light-matter interactions. In particular in cavity and circuit QED these models have been tremendously successful and have been employed in combination with the famous input-output formalism to compute, for example, scattering observables. Recently, however, extreme regimes, such as the overlapping modes and ultra-strong coupling regime, have become accessible in various experimental platforms. In these regimes the applicability of input-output models has been debated. In this talk, we will present an ab-initio method to construct few-mode Hamiltonians that apply even in such extreme regimes [1]. Our theory extends the validity range of Jaynes-Cummings type models without abandoning their conceptual and computational simplicity. In a nutshell, our scheme provides a way to extract relevant degrees of freedom from a structured environment in an open quantum system, allowing to construct a non-perturbative expansion in the mode number. We will outline implications for a broad range of platforms, including quantum optics with non-Hermitian degeneracies [2], multi-mode strong coupling [3], and quantum scattering theory in general [4]. [1] Lentrodt & Evers (2018) arXiv:1812.08556, [2] Özdemir et. al. Nat. Mat. 18 783 (2019), [3] Krimer et. al. Phys. Rev. A 89 033820 (2014), [4] Rotter & Gigan Rev. Mod. Phys. 89 015005 (2017)