Erlangen 2022 – scientific programme

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SYQC: Symposium Quantum Cooperativity of Light and Matter

SYQC 1: Quantum Cooperativity of Light and Matter - Session 1

SYQC 1.1: Invited Talk

Thursday, March 17, 2022, 10:30–11:00, Audimax

Super- and subradiant states of an ensemble of cold atoms coupled to a nanophotonic waveguide — •Arno Rauschenbeutel — Department of Physics, Humboldt-Universität zu Berlin, Germany

We experimentally and theoretically investigate collective radiative effects in an ensemble of cold atoms coupled to a single-mode optical nanofiber. Our analysis unveils the microscopic (i.e., atom per atom) dynamics of the system, showing that collective interactions gradually build up along the atomic ensemble in the direction of propagation of the nanofiber-guided excitation light pulses. Our theoretical results are supported by time-resolved measurements of the light transmitted and reflected by the atomic ensemble. In particular, when the excitation pulse is switched off on a time scale much shorter than the atomic lifetime, a superradiant decay up to 17 times faster than the single-atom decay rate is observed in the forward direction, while no speed-up occurs in the backward direction. For longer time scales, our measurements reveal the evolution of the ensemble from the superradiant state to a set of states that are fully subradiant with respect to the nanofiber-guided mode. Notably, our theoretical model identifies this complex dynamics as a key feature of the time evolution of one-dimensional systems prepared in a timed Dicke state. Our results highlight the unique opportunities offered by nanophotonic cold-atom systems for the experimental investigation of collective light-matter interaction.