Topological phases of lattice bosons with a dynamical gauge field
Optical lattices with a complex-valued tunnelling term have become a standard way of studying gauge-field physics with cold atoms. If the complex phase of the tunnelling is made density-dependent, such system features even a self-interacting or dynamical magnetic field. In this paper we study the scenario of a few bosons in either a static or a dynamical gauge field by means of exact diagonalization. The topological structures are identified computing their Chern number. Upon decreasing the atom-atom contact interaction, the effect of the dynamical gauge field is enhanced, giving rise to a phase transition between two topologically non-trivial phases.
Theoretical barograms have been calculated for acoustic-gravity waves ::: generated by underground explosions. Two formulations were used. 1) The ::: thermally modeled gravitating atmosphere is excited by a time varying deformation of the earth's surface. The final deformation is the static ::: surface displacement due to a point pressure source at depth in an elastic ::: half-space. 2) The same atmosphere overlying a multilayered half-space ::: is excited by a point pressure source at depth in the solid medium.