Coherent Dynamics of BECs in Periodically Driven Optical Lattice

J. Maslek, Thomas Boulier, Carlos Bracamontes +2 more

Hans Lignier, Carlo Sias, D. Ciampini +4 more

We report on measurements of dynamical suppression of interwell tunneling of a Bose-Einstein condensate (BEC) in a strongly driven optical lattice. The strong driving is a sinusoidal shaking of the lattice corresponding to a time-varying linear potential, and the tunneling is measured by letting the BEC freely expand in the lattice. The measured tunneling rate is reduced and, for certain values of the shaking parameter, completely suppressed. Our results are in excellent agreement with theoretical predictions. Furthermore, we have verified that, in general, the strong shaking does not destroy the phase coherence of the BEC, opening up the possibility of realizing quantum phase transitions by using the shaking strength as the control parameter.

Augusto Smerzi

Cinque McFarlane - Blake

We report numerical evidence that a clean, periodically driven Bose--Einstein condensate (BEC) on a non-orientable (M"obius-like) lattice exhibits sustained breathing dynamics with giant global phase-coherence revivals at thousands of Floquet cycles. Using an RK4 integration of a driven Gross--Pitaevskii-type model on a $30\times30$ lattice with Möbius boundary flips and a slow spiral rotating potential, we observe an initial decay into a breathing regime followed by a pronounced revival reaching $\sim$64% global phase coherence near period $\sim4896$, and retained coherence $\sim29%$ at 5000 cycles. We analyze winding-number observables and demonstrate that the revivals are topologically driven by the interplay of non-orientability and spiral drive rather than disorder, prethermalization, or measurement feedback. The phenomenon suggests a new class of geometry-protected Floquet coherence with potential experimental realizations in neutral-atom platforms.

Victor Yu. Argonov, Sergey V. Prants

André Eckardt, Christoph Weiß, Martin Holthaus

We demonstrate that the transition from a superfluid to a Mott insulator in the Bose-Hubbard model can be induced by an oscillating force through an effective renormalization of the tunneling matrix element. The mechanism involves adiabatic following of Floquet states, and can be tested experimentally with Bose-Einstein condensates in periodically driven optical lattices. Its extension from small to very large systems yields nontrivial information on the condensate dynamics.