Beyond the Hubbard bands in strongly correlated lattice bosons

Strand, Hugo U. R.; Eckstein, Martin; Werner, Philipp

doi:10.1103/physreva.92.063602

Cited by 16 publications

(20 citation statements)

References 61 publications

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“…6. The normal phase has been studied in detail elsewhere [70] using BDMFT+NCA and agrees qualitatively with the result we obtain using SFA3. The features of the lattice spectral function can be understood by studying the corresponding SFA3 referencesystem spectral function where the resonances can be understood in terms of transitions between local occupation number states.…”

Section: 15supporting

confidence: 84%

“…A 00 (ω) Here we report on the spectral function in the normalphase using SFA3 and compare with previous results in the low-energy range from BDMFT and CT-QMC [69] and in the high-energy range from BDMFT and the noncrossing approximation (NCA) [70]. We also study the finite temperature superfluid spectral function, previously studied in the low-energy range [57,67], and make an extended analysis of its high-energy resonances.…”

Section: 15mentioning

confidence: 68%

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Bosonic self-energy functional theory

et al. 2016

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We derive the self-energy functional theory for bosonic lattice systems with broken U(1) symmetry by parametrizing the bosonic Baym-Kadanoff effective action in terms of one-and two-point self-energies. The formalism goes beyond other approximate methods such as the pseudoparticle variational cluster approximation, the cluster composite boson mapping, and the Bogoliubov+U theory. It simplifies to bosonic dynamical-meanfield theory when constraining to local fields, whereas when neglecting kinetic contributions of noncondensed bosons, it reduces to the static mean-field approximation. To benchmark the theory, we study the Bose-Hubbard model on the two-and three-dimensional cubic lattice, comparing with exact results from path integral quantum Monte Carlo. We also study the frustrated square lattice with next-nearest-neighbor hopping, which is beyond the reach of Monte Carlo simulations. A reference system comprising a single bosonic state, corresponding to three variational parameters, is sufficient to quantitatively describe phase boundaries and thermodynamical observables, while qualitatively capturing the spectral functions, as well as the enhancement of kinetic fluctuations in the frustrated case. On the basis of these findings, we propose self-energy functional theory as the omnibus framework for treating bosonic lattice models, in particular, in cases where path integral quantum Monte Carlo methods suffer from severe sign problems (e.g., in the presence of nontrivial gauge fields or frustration). Self-energy functional theory enables the construction of diagrammatically sound approximations that are quantitatively precise and controlled in the number of optimization parameters but nevertheless remain computable by modest means.

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Section: 15supporting

confidence: 84%

Section: 15mentioning

confidence: 68%

Bosonic self-energy functional theory

et al. 2016

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“…In contrast to the single band Hubbard model the larger Hilbert space of the two-band model results in two ad-0.00 0.05 0.10 0.15 ditional spectral features at energies beyond the Hubbard bands. These resonances come in two classes, thermally activated and quantum fluctuation driven, analogous to what has previously been discussed for the Bose-Hubbard model 66 . The first resonance beyond the Hubbard bands arises from thermally activated electron-hole pair excitations in the ground state, which on particle addition (removal) produces the local transitions |3 → |4 (|1 → |0 ).…”

Section: A Equilibriummentioning

confidence: 57%

Hund's coupling driven photocarrier relaxation in the two-band Mott insulator

et al. 2017

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We study the relaxation dynamics of photo-carriers in the paramagnetic Mott insulating phase of the half-filled two-band Hubbard model. Using nonequilibrium dynamical mean field theory, we excite charge carriers across the Mott gap by a short hopping modulation, and simulate the evolution of the photo-doped population within the Hubbard bands. We observe an ultrafast charge-carrier relaxation driven by emission of local spin excitations with an inverse relaxation time proportional to the Hund's coupling. The photo-doping generates additional side-bands in the spectral function, and for strong Hund's coupling, the photo-doped population also splits into several resonances. The dynamics of the local many-body states reveals two effects, thermal blocking and kinetic freezing, which manifest themselves when the Hund's coupling becomes of the order of the temperature or the bandwidth, respectively. These effects, which are absent in the single-band Hubbard model, should be relevant for the interpretation of experiments on correlated materials with multiple active orbitals. In particular, the features revealed in the non-equilibrium energy distribution of the photocarriers are experimentally accessible, and provide information on the role of the Hund's coupling in these materials.

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“…To show how the intra (uu, ll) and interband (ul, lu) transitions behave in the lattices with staggered symmetry, we consider at first the honeycomb type of lattices (see Eqs. (14) and (15)). For standard honeycomb lattice one gets…”

Section: Dynamical Conductivitymentioning

confidence: 94%

“…It is straightforward to see that the above formulas for honeycomb and brick-wall lattices, have a similar form (see also Eqs. (14) and (15) . Similar behavior of significant differences in the intra and interband transition amplitudes has been very recently reported also for the uniform magnetic field [20].…”

Section: Dynamical Conductivitymentioning

confidence: 96%

Tuning linear response dynamics near the Dirac points in the bosonic Mott insulator

Sajna

2019

Annals of Physics

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Optical lattice systems offer the possibility of creating and tuning Dirac points which are present in the tight-binding lattice dispersions. For example, such a behavior can be achieved in the staggered flux lattice or honeycomb type of lattices. Here we focus on the strongly correlated bosonic dynamics in the vicinity of Dirac points. In particular, we investigate bosonic Mott insulator phase in which quasiparticle excitations have a simple particle-hole interpretation. We show that linear response dynamics around Dirac points, can be significantly engineered at least in two ways: by the type of external perturbation or by changing the lattice properties. The key role is played by the interband transitions. Moreover, we explain that the behavior of these transitions is directly connected to different energy scales of the effective hopping amplitudes for particles and holes. Presented in this work theoretical study about tunability of linear response dynamics near the Dirac points can be directly simulated in the optical lattice systems.

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Beyond the Hubbard bands in strongly correlated lattice bosons

Cited by 16 publications

References 61 publications

Bosonic self-energy functional theory

Bosonic self-energy functional theory

Hund's coupling driven photocarrier relaxation in the two-band Mott insulator

Tuning linear response dynamics near the Dirac points in the bosonic Mott insulator

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