  We investigate a generalisation of the Rabi system in the Bargmann-Fock
representation. In this representation the eigenproblem of the considered
quantum model is described by a system of two linear differential equations
with one independent variable. The system has only one irregular singular point
at infinity. We show how the quantisation of the model is related to asymptotic
behaviour of solutions in a vicinity of this point. The explicit formulae for
the spectrum and eigenfunctions of the model follow from an analysis of the
Stokes phenomenon. An interpretation of the obtained results in terms of
differential Galois group of the system is also given.
