Many-body physics in two-component Bose-Einstein condensates in a cavity: fragmented superradiance and polarization

Axel Lode (1) , Fritz S Diorico , Rugway Wu , Paolo Molignini , Luca Papariello , Rui Lin , Camille Lévêque , Lukas Exl , Marios C Tsatsos , R Chitra , Norbert J Mauser

1 Unibas - Université de Bâle = University of Basel = Basel Universität

We consider laser-pumped one-dimensional two-component bosons in a parabolic trap embedded in a high-finesse optical cavity. Above a threshold pump power, the photons that populate the cavity modify the effective atom trap and mediate a coupling between the two components of the Bose-Einstein condensate. We calculate the ground state of the laser-pumped system and find different stages of self-organization depending on the power of the laser. The modified potential and the laser-mediated coupling between the atomic components give rise to rich many-body physics: an increase of the pump power triggers a self-organization of the atoms while an even larger pump power causes correlations between the self-organized atoms-the BEC becomes fragmented and the reduced density matrix acquires multiple macroscopic eigenvalues. In this fragmented superradiant state, the atoms can no longer be described as two-level systems and the mapping of the system to the Dicke model breaks down.

Mots clés: many-body systems; time-dependent Schrödinger equation; Bose-Einstein condensates; light-matter interaction; multi-component systems; MCTDHB; MCTDH-X; http://ultracold.org

Domaines: Physique Quantique [quant-ph]; Gaz Quantiques [cond-mat.quant-gas]; Physique Numérique [physics.comp-ph]; Agrégats Moléculaires et Atomiques [physics.atm-clus]

Axel Lode, Fritz S Diorico, Rugway Wu, Paolo Molignini, Luca Papariello, et al.. Many-body physics in two-component Bose-Einstein condensates in a cavity: fragmented superradiance and polarization. New Journal of Physics, 2018, 20, pp.055006. ⟨10.1088/1367-2630/aabc3a⟩. ⟨hal-02370288⟩