Pair tunneling of bosonic atoms in an optical lattice

We study the dynamical properties, with special emphasis on mobility, of quantum lattice compactons (QLCs) in a one-dimensional Bose-Hubbard model extended with pair-correlated hopping. These are quantum counterparts of classical lattice compactons (localized solutions with exact zero amplitude outside a given region) of an extended discrete nonlinear Schrödinger equation, which can be derived in the classical limit from the extended Bose-Hubbard model. While an exact one-site QLC eigenstate corresponds to a classical one-site compacton, the compact support of classical several-site compactons is destroyed by quantum fluctuations. We show that it is possible to reproduce the stability exchange regions of the one-site and two-site localized solutions in the classical model with properly chosen quantum states. Quantum dynamical simulations are performed for two different types of initial conditions: "localized ground states" which are localized wave packets built from superpositions of compactonlike eigenstates, and SU(4) coherent states corresponding to classical two-site compactons. Clear signatures of the mobility of classical lattice compactons are seen, but this crucially depends on the magnitude of the applied phase gradient. For small phase gradients, which classically correspond to a slow coherent motion, the quantum time scale is of the same order as the time scale of the translational motion, and the classical mobility is therefore destroyed by quantum fluctuations. For a large phase instead, corresponding to fast classical motion, the time scales separate so that a mobile, localized, coherent quantum state can be translated many sites for particle numbers already of the order of 10.

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“…[8]. The model has been shown to be relevant in both theoretical [15][16][17][18][19] as well as experimental [20] studies.…”

Section: Introductionmentioning

confidence: 99%

Quantum dynamics of lattice states with compact support in an extended Bose-Hubbard model

Jason

Johansson

2013

Phys. Rev. A

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“…Our results will be helpful in realizing the trimer superfluid by a cold atom experiment. In recent years, the Bose-Hubbard model using an onsite attractive interaction [1][2][3][4][5][6][7][8], or with explicit pair tunneling term [9][10][11] has caught the attention of theoretical and experimental physicists. As for atoms with a twobody attractive interaction on an optical lattice, bosons can form an interesting spontaneous pair-tunneling between two of the nearest neighbor sites.…”

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confidence: 99%

Trimer superfluid induced by photoassocation on the state-dependent optical lattice

Zhang

et al. 2014

Phys. Rev. A

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We use the mean-field method, the Quantum Monte-carlo method and the Density matrix renormalization group method to study the trimer superfluid phase and the quantum phase diagram of the Bose-Hubbard model in an optical lattice, with explicit trimer tunneling term. Theoretically, we derive the explicit trimer hopping terms, such as a 3 † i a 3 j , by the Schrieffer-Wolf transformation. In practice, the trimer superfluid described by these terms is driven by photoassociation. The phase transition between the trimer superfluid phase and other phases are also studied. Without the on-site interaction, the phase transition between the trimer superfluid phase and the Mott Insulator phase is continuous. Turning on the on-site interaction, the phase transitions are first order with Mott insulators of atom filling 1 and 2. With nonzero atom tunneling, the phase transition is first order from the atom superfluid to the trimer superfluid. In the trimer superfluid phase, the winding numbers can be divided by three without any remainders. In the atom superfluid and pair superfluid, the vorticities are 1 and 1/2, respectively. However, the vorticity is 1/3 for the trimer superfluid. The power law decay exponents is 1/2 for the non diagonal correlation a †3 i a 3 j , i.e. the same as the exponent of the correlation a † i aj in hardcore bosons. The density dependent atom-tunneling term n 2 i a † i aj and pair tunneling term nia †2 i a 2 j are also studied. With these terms, the phase transition from the empty phase to atom superfluid is first order and different from the cases without the density dependent terms. The phase transition is still first order from the trimer superfluid phase to the atom superfluid. The effects of temperature are studied. Our results will be helpful in realizing the trimer superfluid by a cold atom experiment.

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“…In the presence of the on-site repulsion U and the absence of the single atom hopping t, the ASF state disappears, instead an MI(ρ = 1) phase emerges. Without three-body constraint, the general picture of the phase diagram has been studied by Zhou et al using the MF method 21 . We show here the phase diagram, under threebody constraint, obtained by using the MF method 25 and by the QMC simulations in Fig.…”

Section: Methods and Observablesmentioning

confidence: 99%

“…The system can be reasonably described by explicitly including atompair hopping 19,20 in the ordinary extended Bose-Hubbard model (EBH). Such a pair hopping can also be introduced in atom-molecule coupling system on the state-dependent optical lattice 21 , or by a mechanism based on transportinducing collisions 22 . The resulted Bose-Hubbard Hamiltonian is thus…”

Section: Introductionmentioning

confidence: 99%

Pair supersolid with atom-pair hopping on the state-dependent triangular lattice

2013

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We systematically study an extended Bose-Hubbard model with atom hopping and atom-pair hopping in the presence of a three-body constraint on the triangular lattice. By means of largescale Quantum Monte Carlo simulations, the ground-state phase diagram are studied. We find a continuous transition between the atomic superfluid phase and the pair superfluid when the ratio of the atomic hopping and the atom-pair hopping is adapted. We then focus on the interplay among the atom-pair hopping, the on-site repulsion and the nearest-neighbor repulsion. With on-site repulsion present, we observe first order transitions between the Mott Insulators and pair superfluid driven by the pair hopping. With the nearest-neighbor repulsion turning on, three typical solid phases with 2/3, 1 and 4/3-filling emerge at small atom-pair hopping region. A stable pair supersolid phase is found at small on-site repulsion. This is due to the three-body constraint and the pair hopping, which essentially make the model a quasi hardcore boson system. Thus the pair supersolid state emerges basing on the order-by-disorder mechanism, by which hardcore bosons avoid classical frustration on the triangular lattice. The transition between the pair supersolid and the pair superfluid is first order, except for the particle-hole symmetric point. We compare the results with those obtained by means of mean-field analysis.

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Pair tunneling of bosonic atoms in an optical lattice

Cited by 32 publications

References 30 publications

Quantum dynamics of lattice states with compact support in an extended Bose-Hubbard model

Quantum dynamics of lattice states with compact support in an extended Bose-Hubbard model

Trimer superfluid induced by photoassocation on the state-dependent optical lattice

Pair supersolid with atom-pair hopping on the state-dependent triangular lattice

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