Density Fluctuations across the Superfluid-Supersolid Phase Transition in a Dipolar Quantum Gas

Dimensional crossover in the superfluid-supersolid quantum phase transition

“…A confirmation of the different character of the two phase transitions comes from an analysis of the fluctuations of the contrast. Fluctuations are generally enhanced in the vicinity of a phase transition, including the superfluid-supersolid phase transition [13]. We already noted the presence of shot-to-shot fluctuations of C for the data in Fig.…”

“…This realizes the scenario first depicted by E. Gross [1], ensuring strong superfluidity effects. Thanks to the tunability of the interactions, it is possible to study the quantum phase transition between the superfluid phase, a standard Bose-Einstein condensate, and the supersolid phase [5][6][7]13], in addition to the classical phase transition from a thermal gas to a supersolid [14].…”

“…So far, the quantum phase transition was crossed only for supersolids with 1D lattice structures. Some of the studies reported partial indications of a discontinuous [5,6,8] or a continuous transition [22], while others did not address the character of the transition [13]. So, it is not clear whether in one-row dipolar supersolids one can observe continuous, discontinuous or both types of quantum phase transitions, nor how these transitions relate to the general theory.…”

Self-bound dipolar droplets and supersolids in molecular Bose-Einstein condensates

“…This counterintuitive behavior leads to a rich phase diagram that contains, for example, self-bound quantum droplets [5,6] and supersolid states [7][8][9][10]. While many aspects like rotonic excitation spectra [11][12][13][14][15][16][17][18][19], anisotropic superfluidity [20,21], droplet formation [1,6,22], crystallization in 1D [23][24][25][26][27][28], 2D [3,18,19,29,30] and into more exotic patterns [31,32], have been extensively discussed for weakly-dipolar magnetic atoms, systematic studies for molecules, with their much larger and tunable electric dipole moments, have so far remained scarce. Here, we show that Bose-Einstein condensates of ground-state molecules are ideal candidates to further explore the rich phase diagrams of dipolar Bose gases in experiments [33].…”

Crystallization of Bosonic Quantum Hall States

“…Condensation at non-zero momentum has been predicted in superfluid helium above a critical velocity [47,48]. Roton-like excitations and instabilities in Bose-Einstein condensates were induced via cavity mediated interactions [49,50], spin-orbit coupling [51,52], shaken optical lattices [53,54], driven interactions [55] and dipolar interactions [56][57][58]. These instabilities were tightly connected to evidence for supersolidity, the simultaneous existence of spatial and superfluid order [50,52,[59][60][61][62].…”