Exploring the grand-canonical phase diagram of interacting bosons in optical lattices by trap squeezing

Journal Article · Sun Aug 15 00:00:00 EDT 2010 · Physical Review. A

DOI:https://doi.org/10.1103/PHYSREVA.82.023601· OSTI ID:21456942

Roscilde, Tommaso ^[1]

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1. Laboratoire de Physique, CNRS UMR 5672, Ecole Normale Superieure de Lyon, Universite de Lyon, 46 Allee d'Italie, Lyon, F-69364 (France)

In this article, we theoretically discuss how quantum simulators based on trapped cold bosons in optical lattices can explore the grand-canonical phase diagram of homogeneous lattice boson models, via control of the trapping potential independent of all other experimental parameters (trap squeezing). Based on quantum Monte Carlo, we establish the general scaling relation linking the global chemical potential to the Hamiltonian parameters for the Bose-Hubbard model in a parabolic trap, describing cold bosons in optical lattices; we find that this scaling relation is well captured by a modified Thomas-Fermi scaling behavior - corrected for quantum fluctuations - in the case of sufficiently high density and/or sufficiently weak interactions, and by a mean-field Gutzwiller ansatz over a much larger parameter range. This scaling relation allows us to control experimentally the chemical potential, independent of all other Hamiltonian parameters, via trap squeezing; given that the global chemical potential coincides with the local chemical potential in the trap center, measurements of the central density as a function of the chemical potential give access to the information on the bulk compressibility of the Bose-Hubbard model. Supplemented with time-of-flight measurements of the coherence properties, the measurement of compressibility enables one to discern among the various possible phases realized by bosons in an optical lattice with or without external (periodic or random) potentials - for example, superfluid, Mott insulator, band insulator, and Bose glass. We theoretically demonstrate the trap-squeezing investigation of these phases in the case of bosons in a one-dimensional optical lattice and in a one-dimensional incommensurate superlattice.

• OSTI ID: 21456942
• Journal Information: Physical Review. A, Vol. 82, Issue 2; Other Information: DOI: 10.1103/PhysRevA.82.023601; (c) 2010 The American Physical Society; ISSN 1050-2947
• Country of Publication: United States
• Language: English

Related Subjects

75 CONDENSED MATTER PHYSICS
SUPERCONDUCTIVITY AND SUPERFLUIDITY
BOSONS
COMPRESSIBILITY
DENSITY
FLUCTUATIONS
HAMILTONIANS
HUBBARD MODEL
MEAN-FIELD THEORY
MONTE CARLO METHOD
ONE-DIMENSIONAL CALCULATIONS
PHASE DIAGRAMS
POTENTIALS
RANDOMNESS
SIMULATORS
SUPERFLUIDITY
SUPERLATTICES
THOMAS-FERMI MODEL
TIME-OF-FLIGHT METHOD
TRAPPING
TRAPS
ANALOG SYSTEMS
ATOMIC MODELS
CALCULATION METHODS
CRYSTAL MODELS
DIAGRAMS
FUNCTIONAL MODELS
INFORMATION
MATHEMATICAL MODELS
MATHEMATICAL OPERATORS
MECHANICAL PROPERTIES
PHYSICAL PROPERTIES
QUANTUM OPERATORS
VARIATIONS