Mainz 2017 – wissenschaftliches Programm

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Q: Fachverband Quantenoptik und Photonik

Q 40: Poster: Quantum Optics and Photonics II

Q 40.4: Poster

Mittwoch, 8. März 2017, 17:00–19:00, P OG2

Real-time observation of a quantum phase transition between two insulators — •Nishant Dogra, Lorenz Hruby, Katrin Kröger, Manuele Landini, Tobias Donner, and Tilman Esslinger — HPF D4, Quantum Optics Group, Institute for Quantum Electronics, ETH Zurich,Otto-Stern-Weg-1,Zurich-8093

The phase transition between two insulating phases with different density ordering is thermodynamically possible but can be blocked due to the existence of energy barriers between various stationary states. We explore such a phase transition in a lattice model with competing onsite and global-range interactions in a Bose-Einstein Condensate (BEC). The global-range interactions arise from the coupling of the BEC to a single mode of a high-finesse cavity and illuminating it with a transverse laser-field. In the limit of deep optical lattices, the system favors either a Mott insulator or a charge density wave insulator depending on the relative interaction strength which is tuned via the cavity resonance. The corresponding order parameter can be detected in real time via the cavity light field. We observe a hysteretic loop in the transition between two insulators which we attribute to the existence of metastable states in the system. Moreover, the temporal dynamics of the order parameter across the transition exhibits two different time scales due to the presence of compressible surface states in our system.