Multiphoton Bloch–Siegert shifts and level splittings in a three-level system

Abstract

Abstract. In previous work we studied the spin-boson model in the multiphoton regime, using a rotation that provides a separation between terms that contribute most of the level energies away from resonance, and terms responsible for the level splittings at the anticrossing. Here, we consider a generalization of the spin-boson model consisting of a three-level system coupled to an oscillator. We construct a similar rotation and apply it to the more complicated model. We find that the rotation provides a useful approximation to the energy levels in the multiphoton region of the new problem. We find that good results can be obtained for the level splittings at the anticrossings for resonances involving the lower two levels in regions away from accidental or low-order resonances of the upper two levels.

Excitation transfer in two two-level systems coupled to an oscillator

“…The accuracy was comparable to that obtained for the spin-boson model, and it seems clear that the approach can be applied systematically to higher-spin generalizations of the spin-boson model as well. We also studied a different generalization of the spin-boson model in which a three-level system is coupled to an oscillator [9]. Technical issues associated with the threelevel system made the implementation of the rotation much more challenging; however, in the end we obtained good results for the level shifts, and for the level splitting at the anticrossings, as long as the anticrossing occurred away from other strong resonances which interfere.…”