can only exist in one of two deterministic states (i.e., “heads” or “tails”), and not
something in between. In other words, the individual particle in quantum entangle-
ment does not have a well-defined pure state before measurement.
Since the beginning of the 1990s, the field of quantum information and com-
munication has expanded rapidly, with quantum entanglement being a critical
aspect. Entanglement is still an unresolved “mystery,” but a new world of
“quantum ideas” has been ignited and is actively being pursued. The focus of
this chapter is the generation of correlated and entangled photons in the telecom
band using the Kerr nonlinearity in dispersion-shifted fiber. Of particular interest
are microstructure fibers, in which tailorable dispersion ...