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Q: Fachverband Quantenoptik und Photonik

Q 18: Quantum Gases (Bosons) II

Q 18.2: Vortrag

Montag, 5. März 2018, 14:15–14:30, K 2.020

Creating a superfluid by kinetically driving a Mott insulator — •Gregor Pieplow, Charles E. Creffield, and Fernando Sols — Departamento de Física de Materiales, Universidad Complutense de Madrid, E-28040 Madrid, Spain

We study the effect of time-periodically varying the hopping amplitude (which we term ``kinetic driving'') in a one-dimensional Bose-Hubbard model, such that the time-averaged hopping is zero. By using Floquet analysis we derive a static effective Hamiltonian in which nearest-neighbor single-particle hopping processes are suppressed, but all even higher-order processes are allowed. Unusual many-body features arise from the combined effect of nonlocal interactions and correlated tunneling. At a critical value of the driving, the system passes from a Mott insulator to a superfluid formed by two quasi-condensates with opposite nonzero momenta. A many-body cat state combining the two macroscopically-occupied momentum eigenstates emerges even with hard-wall boundary conditions. We also explore Bogoliubov-de Gennes theory, which allows to infer the nature of the excitations of the fragmented superfluid. This work shows how driving of the hopping energy provides a novel form of Floquet engineering, which enables atypical Hamiltonians and exotic states of matter to be produced and controlled.