Light-induced quantum droplet phases of lattice bosons in multimode cavities

Abstract

Multimode optical cavities can be used to implement interatomic interactions which are highly tunable in strength and range. For bosonic atoms trapped in an optical lattice, cavity-mediated interactions compete with the short-range interatomic repulsion, which we study using an extended Bose-Hubbard model. Already in a single-mode cavity, where the corresponding interaction has an infinite range, a rich phase diagram has been experimentally observed, featuring density-wave and supersolid self-organized phases in addition to the usual superfluid and Mott insulator. Here we show that, for any finite range of the cavity-mediated interaction, quantum self-bound droplets dominate the ground state phase diagram. Their size and in turn density is not externally fixed but rather emerges from the competition between local repulsion and finite-range attraction. Therefore, the phase diagram becomes very rich, featuring both compressible superfluid/supersolid as well as incompressible Mott and density-wave droplets. Additionally, we observe droplets with a compressible core and incompressible outer shells.

Topological quantum critical points in the extended Bose-Hubbard model

“…Due to the fact that extended Bose-Hubbard Hamiltonians are of great relevance in different physical systems [99][100][101][102][103], we expect that our results can stimulate the study of TQCPs in a broad variety of research lines. Finally, as natural extensions of the present work, we believe that the investigation of TQCPs in fermionic systems, where the extra spin degrees of freedom can give rise to interesting topological states, might represent an intriguing topic.…”

Multimode-polariton superradiance via Floquet engineering

“…Multimode superradiance has been recently observed using ultracold bosons coupled to degenerate confocal resonators [28][29][30][31], and is expected to give access to beyond-mean-field effects due to the increased locality of the light-matter coupling [32][33][34][35][36], as well as both static [32] and dynamic [33] frustration. Multimode superradiance is also technologically interesting for implementing quantum models for associative memory, as studied both for confocal cavitites [37] and non-degenerate cavities with multi-frequency drive [38].…”

Formation and fragmentation of quantum droplets in a quasi-one dimensional dipolar Bose gas

“…The competition of short and long-range interactions in condensed matter systems gives rise to a rich variety of phases ranging from stripes 1,2 or checkerboard phases 3 to a periodic lattices in two dimensions 4 , or to droplet phases in three, two and quasi-one dimension 5 . The advent of Bose-Einstein condensation of lanthanides atoms [6][7][8] with large magnetic moments (like 164 Dy or 166 Er) has opened the fascinating perspective of long range dipolar interactions in bosonic systems 9 .…”