1964: Theory of a laser amplifier that extended Lamb theory to account for space dependence. This was the first formulation of the coupled field-matter equations with space dependence (later called "Maxwell-Bloch equations"). It predicted invariant pulses propagating at the light speed (the nonlinearity compensating for dispersion). These results were later applied to absorbing media (self induced transparency).
1969: Introduced a fundamental parameter of the resonant interaction[41,44] that is, the correlation length in the cooperative spontaneous emission of atoms prepared incoherently in an excited state. It does not depend on boundary conditions (as the mirrors in a laser), nor on an external field (as in coherent spectroscopy), but it is an intrinsic parameter of many body optical interactions.
1970: Theory of the atomic coherent states[48,51,54] as a basis for a statistical description of coherent phenomena in resonant spectroscopy.
1978: Theory of the two photon optical bistability, observed four years later.
1998: Quantum interferenceof macroscopically distinct states in parametric optical generation.
2000: Dissipative dynamics of an open Bose-Einstein condensate (BEC): pattern formation[288,289].
2002: Macroscopic quantum coherence in BEC: attractive and repulsive interactions[306,307,312].