Superfluidity in Patterned Quantum Phases

Dear Colleagues,

The well-known phenomenon of superfluidity is presently drawing a broad interest in condensed matter and statistical mechanics. Several new experiments, dealing mainly with degenerate quantum gases at low temperature, have in fact shown that gauge invariance may survive regardless of the presence of some other symmetries describing a long or quasi-long range order. Pattern formation and quasicrystal structures observed in cavities, realization of three-dimensional quantum droplets by tuning Feshbach resonances, and spin–orbit coupled Bose–Einstein condensates perhaps represent the most intriguing examples so far.

By means of quantum Monte Carlo simulations, preliminary findings have pointed out that, considering two-body potentials, the establishment of quantum clusters or droplet phases can be sketched out in terms of interplay among quantum-mechanical exchanges, thermal fluctuations, and the symmetry of the system. Nevertheless, to date, mean-field approaches still rely on pivotal works proposed some decades ago by E. P. Gross and A. J. Leggett. With this limit in mind, we are capable of providing a good description of the supersolid phase.

Certainly, the aforementioned theoretical knowledge needs to be further refined to entirely understand the physics recently observed in the laboratory. For these reasons, it is strategic to grasp the actual state-of-the-art of a macroscopic quantity such as superfluidity, whose features are essential in this contest. The aim of the present Special Issue is then to bring together all the expertise (topological and quantum field theories as well as advanced numerical methodologies) that have currently been accomplishing significant progress in the topic.

Finally, we hope to facilitate the discussion and thus offer the widest possible knowledge on these special examples of quantum phases.

Dr. Fabio Cinti
Guest Editor

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• crystallisation in ultra-cold systems
• cluster physics
• quantum droplets
• quantum quasicrystals
• supersolidity
• dipolar systems
• superfluidity in homogeneous and non-homogeneous systems
• superfluidity of coupled systems
• spin-orbit Bose–Einstein condensates
• bosons confined on curved space