Regensburg 2019 – wissenschaftliches Programm

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TT: Fachverband Tiefe Temperaturen

TT 69: Cold Atomic Gases and Superfluids

TT 69.3: Vortrag

Freitag, 5. April 2019, 10:00–10:15, H23

Floquet induced superfluidity — •Shijie Hu¹, Xue-Feng Zhang², Tao Wang^1,2,3, Axel Pelster¹, and Sebastian Eggert¹ — ¹Technische Universität Kaiserslautern — ²Chongqing University — ³Wuhan Institute of Technology

We consider two states of hard-core bosons with periodically modulated Rabi driving in a one dimensional (1D) optical lattice, which is equivalent to the 1D Hubbard model with time-periodic interactions. Using Floquet theory the model can be mapped to an effective Hamiltonian for high frequencies, which is described by a static interactions and hopping parameters that depend on the local densities. In particular, if the density difference of one species is non-zero on neighboring sites, the effective hopping of the other species is reduced and can even take on negative values. Using a combination of analytic calculations and different advanced numerical simulations we establish the full quantum phase diagram for half-integer filling for this system. Surprisingly, the density-dependent reduction of hopping drives a quantum phase transition into a superfluid phase. For negative hopping a previously unknown state is found, where one species induces a gauge phase of the other species, which leads to a superfluid phase of gauge-dressed particles. The corresponding experimental signatures in time-of-flight experiments are calculated and show characteristic signatures of the different phases. The phase transition line between the two superfluid phases corresponds to an exactly solvable model with high degeneracy.