Quantum phases and transitions of bosons on a comb lattice

Motivated to elucidate the nature of quantum phases and their criticality when entangled with a correlated quantum bath, we study interacting bosons on a “comb lattice” – a one-dimensional backbone (system) coupled at its sites to otherwise independent one-dimensional “teeth” chains (bath). We map out the corresponding phase diagram, detailing the nature of the phases and phase transitions. Controlled by the backbone and teeth hopping amplitudes, on-site interaction and chemical potential, phases include a Mott-insulator (MI), backbone (LLb) and teeth (LLp) Luttinger liquids, and the long-range ordered incoherent superfluid (iSF). We explore their properties and potential realizations in condensed matter and cold-atom experiments and simulations.