Publication: Universal Scaling of the Conductivity at the Superfluid-Insulator Transition

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Title	Universal Scaling of the Conductivity at the Superfluid-Insulator Transition
Authors/Editors*	J. Smakov and E. S. Sorensen
Where published*	Physical Review Letters
How published*	Journal
Year*	2005
Volume	95
Number	-1
Pages	180603
Publisher	APS
Keywords
Link	http://link.aps.org/doi/10.1103/PhysRevLett.95.180603
Abstract	The scaling of the conductivity at the superfluid-insulator quantum phase transition in two dimensions is studied by numerical simulations of the Bose-Hubbard model. In contrast to previous studies, we focus on properties of this model in the experimentally relevant thermodynamic limit at finite temperature T. We find clear evidence for deviations from Ïk scaling of the conductivity towards Ïk/T scaling at low Matsubara frequencies Ïk. By careful analytic continuation using PadÃ© approximants we show that this behavior carries over to the real frequency axis where the conductivity scales with Ï/T at small frequencies and low temperatures. We estimate the universal dc conductivity to be Ï*=0.45(5)Q2/h, distinct from previous estimates in the T=0, Ï/Tâ«1 limit.