Qv. Lawande et al., Pancharatnam phase for a system of a two-level atom interacting with a quantized field in a cavity, PHYS LETT A, 251(3), 1999, pp. 164-168
We derive an expression for the Pancharatnam phase for the entangled state
of a single two-level atom interacting with a single electromagnetic field
mode in an ideal cavity with the atom undergoing either a one- or a two-pho
ton transition. It is shown that the Pancharatnam phase explicitly contains
information about the statistics of the field and atomic coherence. (C) 19
99 Elsevier Science B.V.