Adiabatic creation of entangled states by a bichromatic field designed   from the topology of the dressed eigenenergies
  Preparation of entangled pairs of coupled two-state systems driven by a bichromatic external field is studied. We use a system of two coupled spin-1/2 that can be translated into a three-state ladder model whose intermediate state represents the entangled state. We show that this entangled state can be prepared in a robust way with appropriate fields. Their frequencies and envelopes are derived from the topological properties of the model. 
S. Guerin, R. Unanyan, L. P. Yatsenko and H. R. Jauslin