Phase diagram of a bosonic ladder with two coupled chains

Abstract

We study a bosonic ladder with two coupled chains using the finite-size density-matrix renormalization group method. We show that in a commensurate bosonic ladder the critical on-site interaction $({U}_{C})$ for the superfluid to Mott insulator transition gets larger as the interchain hopping $({t}_{\ensuremath{\perp}})$ increases. We analyze this quantum phase transition and obtain the phase diagram in the ${t}_{\ensuremath{\perp}}\ensuremath{-}U$ plane. We also consider the asymmetric case where the on-site interactions are different in the two chains and have shown that the system as a whole will not be in the Mott insulator phase unless both the chains have on-site interactions greater than the critical value.