Theoretical analysis of the spectroscopy of atomic Bose-Hubbard systems Article Swipe
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· 2016
· Open Access
·
· DOI: https://doi.org/10.1103/physreva.93.043608
· OA: W2212373220
We provide a numerical method to calculate comprehensively the microwave and\nthe laser spectra of ultracold bosonic atoms in optical lattices at finite\ntemperatures. Our formulation is built up with the sum rules, up to the second\norder, derived from the general principle of spectroscopy. The sum rule\napproach allows us to discuss the physical origins of a spectral peak shift and\nalso a peak broadening. We find that a spectral broadening of superfluid atoms\ncan be determined from number fluctuations of atoms, while that of normal-state\natoms is mainly attributed to quantum fluctuations resulting from hopping of\natoms. To calculate spectra at finite temperatures, based on the sum rule\napproach, we provide a two-mode approximation assuming that spectra of the\nsuperfluid and normal state atoms can be calculated separately. Our method can\nproperly deal with multi-peak structures of spectra resulting from thermal\nfluctuations and also coexisting of the superfluid and the normal states. By\ncombining the two-mode approximation with a finite temperature Gutzwiller\napproximation, we calculate spectra at finite temperatures by considering\nrealistic systems, and the calculated spectra show nice agreements with those\nin experiments.\n
