S. Ejima, H. Fehske, F. Gebhard
In order to identify possible experimental signatures of the superfluid to
Mott-insulator quantum phase transition we calculate the charge structure
factor $S(k,\omega)$ for the one-dimensional Bose-Hubbard model using the
dynamical density-matrix renormalisation group (DDMRG) technique. Particularly
we analyse the behaviour of $S(k, \omega)$ by varying---at zero
temperature---the Coulomb interaction strength within the first Mott lobe. For
strong interactions, in the Mott-insulator phase, we demonstrate that the DDMRG
results are well reproduced by a strong-coupling expansion, just as the
quasi-particle dispersion. In the superfluid phase we determine the linear
excitation spectrum near $k=0$ and compare the DDMRG data with results from
mean-field theory.
View original:
http://arxiv.org/abs/1110.4498
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