Three-body bound states of two bosons and one impurity in one dimension

We investigate one-dimensional three-body systems composed of two identical bosons and one imbalanced atom (impurity) with two-body and three-body zero-range interactions. For the case in the absence of three-body interaction, we give a complete phase diagram of the number of three-body bound states in the whole region of mass ratio via the direct calculation of the Skornyakov-Ter-Martirosyan equations. We demonstrate that other low-lying three-body bound states emerge when the mass of the impurity particle is not equal to another two identical particles. We can obtain not only the binding energies but also the corresponding wave functions. When the mass of impurity atom is vary large, there are at most three three-body bound states. We then study the effect of three-body zero-range interaction and unveil that it can induces one more three-body bound state at a certain region of coupling strength ratio under a fixed mass ratio.

Exact mobility edges, $mathcal{PT}$-symmetry breaking and skin effect in one-dimensional non-Hermitian quasicrystals

We propose a general analytic method to study the localization transition in one-dimensional quasicrystals with parity-time ($mathcal{PT}$) symmetry, described by complex quasiperiodic mosaic lattice models. By applying Avilas global theory of quasiperiodic Schrodinger operators, we obtain exact mobility edges and prove that the mobility edge is identical to the boundary of $mathcal{PT}$-symmetry breaking, which also proves the existence of correspondence between extended (localized) states and $mathcal{PT}$-symmetry ($mathcal{PT}$-symmetry-broken) states. Furthermore, we generalize the models to more general cases with non-reciprocal hopping, which breaks $mathcal{PT}$ symmetry and generally induces skin effect, and obtain a general and analytical expression of mobility edges. While the localized states are not sensitive to the boundary conditions, the extended states become skin states when the periodic boundary condition is changed to open boundary condition. This indicates that the skin states and localized states can coexist with their boundary determined by the mobility edges.

Non-Hermitian mobility edges in one-dimensional quasicrystals with parity-time symmetry

We investigate localization-delocalization transition in one-dimensional non-Hermitian quasiperiodic lattices with exponential short-range hopping, which possess parity-time ($mathcal{PT}$) symmetry. The localization transition induced by the non-Hermitian quasiperiodic potential is found to occur at the $mathcal{PT}$-symmetry-breaking point. Our results also demonstrate the existence of energy dependent mobility edges, which separate the extended states from localized states and are only associated with the real part of eigen-energies. The level statistics and Loschmidt echo dynamics are also studied.