The relationships between certain important nonclassical states of the quan
tized field and the coherent states associated with the SU(2) and SU(1,1) L
ie groups and associated Lie algebras is briefly reviewed. As an example of
the utility of group theoretical methods in quantum optics, a method for g
enerating maximally entangled photonic states is discussed. These states ma
y be of great importance for achieving Heisenberg-limited interferometry an
d in beating the diffraction limit in lithography. (C) 2001 Optical Society
of America.