Density-dependent synthetic magnetism for ultracold atoms in optical lattices

Abstract

Raman-assisted hopping can allow for the creation of density-dependent synthetic magnetism for cold neutral gases in optical lattices. We show that the density-dependent fields lead to a nontrivial interplay between density modulations and chirality. This interplay results in a rich physics for atoms in two-leg ladders, characterized by a density-driven Meissner-superfluid to vortex-superfluid transition, and a nontrivial dependence of the density imbalance between the legs. Density-dependent fields also lead to intriguing physics in square lattices. In particular, it leads to a density-driven transition between a nonchiral and a chiral superfluid, both characterized by nontrivial charge density-wave amplitude. We finally show how the physics due to the density-dependent fields may be easily probed in experiments by monitoring the expansion of doublons and holes in a Mott insulator, which presents a remarkable dependence on quantum fluctuations.

Stroboscopic versus nonstroboscopic dynamics in the Floquet realization of the Harper-Hofstadter Hamiltonian

“…Theoretical models based on Floquet's theorem are being developed to simulate systems in regimes otherwise inaccessible in conventional condensed matter materials [2][3][4][5][6][7][8][9][10][11][12][13][14][15][16][17][18] . Experimentally, cold atoms' unique controllability was employed to observe dynamical localisation and phase-coherence in strongly shaken bosonic systems [19][20][21][22][23][24] .…”

Staircase of crystal phases of hard-core bosons on the kagome lattice

“…In the rest of the phase diagram, while short-range correlations within the clusters are computed exactly, the mean-fields carry information about the thermodynamic limit allowing for potential breakdown of symmetries and the concurrent stabilization of long-range ordered phases. These CB Gutzwiller wave functions permit the description of quantum phases characterized by the onset of long-range superfluid order, signaled by the occurrence of BEC at various momenta, as well as crystal or superfluid phases characterized by chiral currents 33,44 . On the contrary, ED consists of a single diagonalization performed on a finite cluster with PBC.…”

Density-induced geometric frustration of ultra-cold bosons in optical lattices

“…the created gauge fields and lattice geometries are static. Recently, it has been proposed that laser-assisted hopping may result in the realization of density-dependent gauge fields [12][13][14][15] for which the hopping rates (in particular their phase) is dynamically modified depending on the local lattice occupation number. In one-dimensional lattices density-dependent gauge fields result in the anyon-Hubbard model [12,13], which is characterized by gauge-driven Mott-insulator (MI) to superfluid (SF) transitions, Mott phases at negative on-site interactions, and by the appearance of novel phases(in particular the so-called partially paired superfluid (PP) [13]).…”

“…In one-dimensional lattices density-dependent gauge fields result in the anyon-Hubbard model [12,13], which is characterized by gauge-driven Mott-insulator (MI) to superfluid (SF) transitions, Mott phases at negative on-site interactions, and by the appearance of novel phases(in particular the so-called partially paired superfluid (PP) [13]). In higher-dimensions, laser-assisted hopping may induce under proper conditions density-dependent magnetism, which results in a non-trivial interplay between density modulation and chirality [14].…”