Rhombi-chain Bose-Hubbard model: Geometric frustration and interactions

Chiara, Gabriele De; Rizzi, Matteo

doi:10.1103/physrevb.98.184508

Cited by 15 publications

(19 citation statements)

References 103 publications

(160 reference statements)

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“…The diamond chain has been recently implemented with photonic lattices [77], while excited orbital angular momentum states of ultracold atoms have been proposed as a new venue for implementing the same model [78]. We note also a recent theoretical work [79] where the phase diagram of the diamond chain with a Bose-Hubbard interaction term has been studied in detail and possible strategies for its implementation have been described.…”

Section: Discussionmentioning

confidence: 97%

Preformed pairs in flat Bloch bands

et al. 2018

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In a flat Bloch band the kinetic energy is quenched and single particles cannot propagate since they are localized due to destructive interference. Whether this remains true in the presence of interactions is a challenging question because a flat dispersion usually leads to highly correlated ground states. Here we compute numerically the ground state energy of lattice models with completely flat band structure in a ring geometry in the presence of an attractive Hubbard interaction. We find that the energy as a function of the magnetic flux threading the ring has a half-flux quantum Φ0/2 = hc/(2e) period, indicating that only bound pairs of particles with charge 2e are propagating, while single quasiparticles with charge e remain localized. For some one dimensional lattice models we show analytically that in fact the whole many-body spectrum has the same periodicity. Our analytical arguments are valid for both bosons and fermions, for generic interactions respecting some symmetries of the lattice and at arbitrary temperatures. Moreover for the same one dimensional lattice models we construct an extensive number of exact conserved quantities. These conserved quantities are associated to the occupation of localized single quasiparticle states and force the single-particle propagator to vanish beyond a finite range. Our results suggest that in lattice models with flat bands preformed pairs dominate transport even above the critical temperature of the transition to a superfluid state.

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Section: Discussionmentioning

confidence: 97%

Preformed pairs in flat Bloch bands

et al. 2018

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“…Until recently, most of the theoretical studies have focused on MBL induced by the disorders encoded in the on-site potentials, hopping amplitudes and interactions, as well as quasi-periodic potentials [13]. On the other hand very recently, disorder-free AL/MBL-like phenomena have been revealed in a Wannier-Stark ladder [14][15][16], dipolar atom gases in an optical lattice [17], some lattice-gauge theoretical models [18][19][20][21], quantum Hall systems [22], a diamond chain system [23][24][25], and a disorder-free spin chain [26][27][28][29].…”

Section: Introductionmentioning

confidence: 99%

Flat-band many-body localization and ergodicity breaking in the Creutz ladder

2020

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We study disorder-free many-body localization in the flat-band Creutz ladder, which was recently realized in cold-atoms in an optical lattice. In a non-interacting case, the flat-band structure of the system leads to a Wannier wavefunction localized on four adjacent lattice sites. In the flat-band regime both with and without interactions, the level spacing analysis exhibits Poisson-like distribution indicating the existence of disorder-free localization. Calculations of the inverse participation ratio support this observation. Interestingly, this type of localization is robust to weak disorders, whereas for strong disorders, the system exhibits a crossover into the conventional disorder-induced manybody localizated phase. Physical picture of this crossover is investigated in detail. We also observe nonergodic dynamics in the flat-band regime without disorder. The memory of an initial density wave pattern is preserved for long times.

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“…In particular, single particle (non-interacting) eigenstates in AB cages are compactly localized but non-orthogonal, such that interactions induce two-particle hopping processes. This destroys the caging, leading to delocalized bound pairs, novel strongly correlated quantum phases such as 4e superconductivity, and time-reversal symmetry breaking ground states [22][23][24][25][26][27][28][29][30][31].…”

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confidence: 99%

Nonlinear symmetry breaking of Aharonov-Bohm cages

et al. 2019

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We study the influence of mean field cubic nonlinearity on Aharonov-Bohm caging in a diamond lattice with synthetic magnetic flux. For sufficiently weak nonlinearities the Aharonov-Bohm caging persists as periodic nonlinear breathing dynamics. Above a critical nonlinearity, symmetry breaking induces a sharp transition in the dynamics and enables stronger wavepacket spreading. This transition is distinct from other flatband networks, where continuous spreading is induced by effective nonlinear hopping or resonances with delocalized modes, and is in contrast to the quantum limit, where two-particle hopping enables arbitrarily large spreading. This nonlinear symmetry breaking transition is readily observable in femtosecond laser-written waveguide arrays.

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Rhombi-chain Bose-Hubbard model: Geometric frustration and interactions

Cited by 15 publications

References 103 publications

Preformed pairs in flat Bloch bands

Preformed pairs in flat Bloch bands

Flat-band many-body localization and ergodicity breaking in the Creutz ladder

Nonlinear symmetry breaking of Aharonov-Bohm cages

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