Phase diagram of the disordered Bose-Hubbard model
- Department of Physics, University of Colorado, Boulder, Colorado 80309 (United States)
- Physics Department, Harvard University, Cambridge, Massachusetts 02138 (United States)
- Department of Physics, University of Massachusetts, Amherst, Massachusetts 01003 (United States)
- Theoretische Physik, ETH Zurich, 8093 Zurich (Switzerland)
We establish the phase diagram of the disordered three-dimensional Bose-Hubbard model at unity filling which has been controversial for many years. The theorem of inclusions, proven by Pollet et al. [Phys. Rev. Lett. 103, 140402 (2009)] states that the Bose-glass phase always intervenes between the Mott insulating and superfluid phases. Here, we note that assumptions on which the theorem is based exclude phase transitions between gapped (Mott insulator) and gapless phases (Bose glass). The apparent paradox is resolved through a unique mechanism: such transitions have to be of the Griffiths type when the vanishing of the gap at the critical point is due to a zero concentration of rare regions where extreme fluctuations of disorder mimic a regular gapless system. An exactly solvable random transverse field Ising model in one dimension is used to illustrate the point. A highly nontrivial overall shape of the phase diagram is revealed with the worm algorithm. The phase diagram features a long superfluid finger at strong disorder and on-site interaction. Moreover, bosonic superfluidity is extremely robust against disorder in a broad range of interaction parameters; it persists in random potentials nearly 50 ({exclamation_point}) times larger than the particle half-bandwidth. Finally, we comment on the feasibility of obtaining this phase diagram in cold-atom experiments, which work with trapped systems at finite temperature.
- OSTI ID:
- 21287114
- Journal Information:
- Physical Review. B, Condensed Matter and Materials Physics, Vol. 80, Issue 21; Other Information: DOI: 10.1103/PhysRevB.80.214519; (c) 2009 The American Physical Society; Country of input: International Atomic Energy Agency (IAEA); ISSN 1098-0121
- Country of Publication:
- United States
- Language:
- English
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