Excitation spectrum and supersolidity of a two-leg bosonic ring ladder

Abstract

We consider a system of weakly interacting bosons confined on a planar double lattice ring subjected to two artificial gauge fields. This system is known to display three phases, the Meissner phase where the flow of particles is carried at the edges of the system without transverse current, a vortex phase characterized by non-zero transverse current, and a biased-ladder phase, characterized by an imbalance of the population of the two rings. We use the Bogoliubov approximation to determine the excitation spectrum in the three phases, the dynamic structure factor and the quantum fluctuation corrections to the first-order correlation function. Our analysis reveals supersolid features as well as Josephson modes, corresponding to out-of-phase modes of the finite ring.PACS numbers: 05.30.-d,67.85.-d,67.85.Pq arXiv:1910.06410v1 [cond-mat.quant-gas]

Spectral Function of a Boson Ladder in an Artificial Gauge Field

“…In the previous sections, we have derived the expressions for the spectral function with the bosonization technique, valid at intermediate and strong interactions. In the regime of very weak interactions and large filling of the lattice, a complementary approach is provided by the Bogoliubov theory [28]. The system is described by a two-component Bose-Einstein condensate with wavefunction Ψ…”

“…This would display a well defined gapped or gapless dispersion, respectively, in the Meissner and in the Vortex phase. However, such correlation function would not be sensitive to the incommensuration in the weak interchain hopping regime, although it displays incommensuration features at weak interactions and large interchain hopping [4,28]. A better indicator of incommensuration in all regimes is provided by the spectral function of the bosonic particles.…”

Spectral Function of a Boson Ladder in an Artificial Gauge Field

“…In the previous sections we have derived the expressions for the spectral function with the bosonization technique, valid at intermediate and strong interactions. In the regime of very weak interactions and large filling of the lattice, a complementary approach is provided by the Bogoliubov theory [27]. The system is described by a two-component Bose-Einstein condensate with wavefunction Ψ…”

“…where h σ νj and Q σ νj are the Bogoliubov mode wavefunctions with energy ω ν and γ ν are the quasiparticle creation and destruction field operators, satisfying bosonic commutation relations (see [27] for the full expressions).…”

“…This would display a well defined gapped or gapless dispersion respectively in the Meissner and in the Vortex phase. However, such correlation function would not be sensitive to the incommensuration in the weak interchain hopping regime, although it displays incommensuration features at weak interactions and large interchain hopping [4,27]. A better indicator of incommensuration in all regimes is provided by the spectral function of the bosonic particles.…”