For multi-level time-dependent quantum systems one can construct
superadiabatic representations in which the coupling between separated levels
is exponentially small in the adiabatic limit. Based on results from [BeTe1]
for special Hamiltonians we explicitly determine the asymptotic behavior of the
exponentially small coupling term for generic two-state systems with
real-symmetric Hamiltonian. The superadiabatic coupling term takes a universal
form and depends only on the location and the strength of the complex
singularities of the adiabatic coupling function.
As shown in [BeTe1], first order perturbation theory in the superadiabatic
representation then allows to describe the time-development of exponentially
small adiabatic transitions and thus to rigorously confirm Michael Berry's
[Ber] predictions on the universal form of adiabatic transition histories.