Freiburg 2024 – scientific programme

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SYQO: Symposium Ultrafast Quantum Nano-Optics

SYQO 1: Ultrafast Quantum Nano-Optics

SYQO 1.2: Invited Talk

Friday, March 15, 2024, 11:30–12:00, Paulussaal

Dissipative Many-Body Dynamics in Atomic Subwavelength Arrays in Free Space — •Stefan Ostermann — Department of Physics, Harvard University, Cambridge, Massachusetts 02138, USA

The photon emission properties of atomic arrays with subwavelength lattice spacing are modified by light-induced dipole-dipole interactions, giving rise to effects like super- and subradiance. Recent advances in experimental techniques have enabled the generation of well-controlled periodic arrangements of individual atoms in free space. This development has sparked widespread interest in investigating the fundamental physics of these extended long-range interacting structures, as well as in harnessing them as efficient light-matter interfaces for future quantum technologies. While many aspects of the single excitation regime of subwavelength emitter geometries were studied over the past decade, investigating the full dissipative many-body problem involving multiple excitations remains an ongoing research effort. I will present our recent results elucidating some core characteristics of the multi-excitation regime. We characterize the superradiant out-of-equilibrium dynamics for large system sizes and extract the scaling of the superradiant peak with particle number in fully inverted arrays. Additionally, we identify the critical excitation number for superradiance in partially excited arrays in 1D and 2D. Related to this, we show that maximal coupling to subradiant states is achieved if half of the atoms are incoherently excited initially. Finally, I will present an analysis of the steady-state phase diagram for a strongly driven system, with a particular focus on its radiative properties.

Keywords: quantum optics; light-matter interaction; superradiance; subradiance; cooperative effects