Correlation functions at generic superfluid-insulator transition in two dimensions

Abstract

We have investigated the correlation functions of interacting bosons at the generic superfluid-insulator transition, a prototypical quantum phase transition, in two dimensions in the spherical limit. The spatial correlation functions show non-power-law behavior consisting of two parts: a short-range correlation due to particle-hole pair excitations and a long-range off-diagonal order due to single-particle condensation. The temporal correlation functions, on the other hand, show a power-law behavior.