Weak chaos in a photon–qubit system with anisotropic interaction

A generalized model of the interaction of a superconducting qubit with the electromagnetic field of a cavity, which is conducted through capacitance (electric dipole interaction) and inductance (magnetic dipole interaction)–the anisotropic Rabi model–is considered. It has been shown that the Hilbert space of the anisotropic model can be split into two subspaces orthogonal in the pseudospin. In this case, the spectra of the Hamiltonians acting in these subspaces have a complex behavior. Analytical and numerical calculations have been performed to clarify the nature of weak chaos in the considered system. The class of universality of the anisotropic Rabi model in the hierarchy of systems with quantum chaos, as well as possible consequences for the theory of quantum measurements, has been discussed.