  We present a theoretical analysis of a novel scheme for optical cooling of
particles that does not in principle require a closed optical transition. A
tightly confined laser beam interacting with a trapped particle experiences a
phase shift, which upon reflection from a mirror or resonant microstructure
produces a time-delayed optical potential for the particle. This leads to a
nonconservative force and friction. A quantum model of the system is presented
and analyzed in the semiclassical limit.
