Scientific Calendar Event



Starts 21 Oct 2025 14:00
Ends 21 Oct 2025 15:00
Central European Time
Luigi Stasi Seminar Room (Leonardo Building) and via Zoom

Leon Mixa
(University of Hamburg)
 
 
Abstract:
Quantum droplets are an exotic state of matter which emerges from zero-point energy corrections to the ground state resulting in a self-bound many-body system. We present a theoretical framework for a new type of quantum droplet. In our case, the correction is provided by a single collective mode of the finite-size system facilitated by a global interaction of particles. This situation can be engineered by coupling a dilute Bose-Einstein condensate to a dissipative bosonic mode. We investigate the example of an optical cavity with a transverse pumping of the atoms and discuss the features of this driven-dissipative setup. The vacuum fluctuations of the cavity mediate an effective long-range atom-atom interaction. Using the Bogoliubov formalism, we demonstrate that this interaction leads to the formation of a distinct roton mode. The zero-point energy of the roton mode scales favorably with the atomic volume and thus competes with the repulsive contact interaction. This facilitates the formation of the droplet. The quantum energy correction and its crucial scaling are determined by the modes of the light field. We investigate how changing the characteristics of the light field and the coupling parameters affect the droplet. We present temperature effects, including a critical temperature for the droplet. Our results provide analytical expressions for the droplet characteristics and classify the regimes in which the self-bound quantum many-body states emerges.
 
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