L. Jin, Z. Song

We study the phase diagram of a PT symmetric non-Hermitian Bose-Hubbard model. Using both analytical and numerical approaches, we find that even small on-site interaction can break the PT symmetry drastically. It has been demonstrated that the scaling law can be established for the exceptional point in small U limit. Based on numerical approach, we also find that the phase diagram shows rich structure for medium U: there exist multiple regions in which the PT symmetry is unbroken.

http://arxiv.org/abs/1105.6186

Statistical Mechanics (cond-mat.stat-mech); Quantum Physics (quant-ph)