Mainz 2026 – wissenschaftliches Programm
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Q: Fachverband Quantenoptik und Photonik
Q 33: Cavity QED, QED, and Spin-Boson Systems I
Q 33.2: Vortrag
Mittwoch, 4. März 2026, 14:45–15:00, P 4
Collective excitations of dissipative time crystals — •Gage Harmon1, Giovanna Morigi1, and Simon Jäger2 — 1Saarland University — 2University of Bonn
We investigate the dynamical response across phase transitions in dissipative time crystals. Using Floquet theory, we characterize the excitation spectra associated with the transition from a normal to a time-crystalline phase. Our analysis reveals two distinct types of dynamical phase transitions, distinguished by the behavior of an order parameter: a continuous (second-order) transition, where the order parameter evolves smoothly; and a discontinuous (first-order) transition, where it changes abruptly. The excitation spectra provide clear signatures of these transitions: the continuous transition is accompanied by the closing of a complex gap, whereas the discontinuous transition exhibits the coexistence of two excitation branches. Focusing on a concrete model*cold atoms strongly coupled to an optical cavity*we demonstrate how these excitations can be experimentally probed by driving the cavity with a longitudinal field. This framework not only clarifies the nature of out-of-equilibrium phases but also opens a route toward experimentally probing the universal properties of time-crystalline order.
Keywords: Collective Excitations; Time Crystals; Out-of-equilibrium; Floquet theory