Bosonic Mott Insulator with Meissner Currents

Abstract

We introduce a generic bosonic model exemplifying that (spin) Meissner currents can persist in insulating phases of matter. We consider two species of interacting bosons on a lattice. Our model exhibits separation of charge (total density) and spin (relative density): the charge sector is gapped in a bosonic Mott insulator phase with total density one, while the spin sector remains superfluid due to interspecies conversion. Coupling the spin sector to the gauge fields yields a spin Meissner effect reflecting the long-range spin superfluid coherence. We investigate the resulting phase diagram and describe other possible spin phases of matter in the Mott regime possessing chiral currents as well as a spin-density wave phase. The model presented here is realizable in Josephson junction arrays and in cold atom experiments.

Chiral currents in one-dimensional fractional quantum Hall states

“…It is nonoscillating at zero flux, while it becomes oscillating at nonzero flux. Yet, in a grand-canonical ensemble defined by a chemical potential µ rather than the density n, there is a finite range of nonzero flux where a gap opens, up to a commensurate-incommensurate transition 25,26 , even though the condition in Eq. (B7) is not satisfied.…”

“…When relevant, such operators may open an energy gap even for a finite deviation from this exact flux up to a commensurate-incommensurate transition 25,26 . The above condition is met when the filling factor Eq.…”

“…We first list the possible perturbations to the Luttinger liquid model 13,25,26 , which include the FQH instability on which we focus. This enables one to obtain conditions for the Luttinger liquid parameter K ρ and density n, under which operators identified as opening FQH gaps are most relevant in the renormalization group (RG) sense.…”

“…1. The possibility that chiral currents screen the orbital magnetic field in a kind of a Meissner phase, was pointed out [25][26][27] and recently observed experimentally 1,28 ; here we focus on the FQH phase.…”

Geometry of system-bath coupling and gauge fields in bosonic ladders: Manipulating currents and driving phase transitions

“…two connected chains. This geometry has been extensively studied both in Josephson junctions arrays and bosonic atoms in optical lattices also in presence of interactions [18][19][20][21][22][23][24][25][26][27][28][29][30][31][32][33][34]. To be highlighted is the emergence of a quantum phase transition for bosonic FIG.…”