This volume contains ten lectures presented in the series ULB Lectures in Nonlinear Optics at the Universite Libre de Bruxelles during the period
October 28 to November 4, 1991. A large part of the first six lectures is
taken from material prepared for a book of somewhat larger scope which
will be published by Springer under the title Quantum Statistical Methods
in Quantum Optics. The principal reason for the early publication of the
present volume concerns the material contained in the last four lectures.
Here I have put together, in a more or less systematic way, some ideas about
the use of stochastic wavefunctions in the theory of open quantum optical
systems. These ideas were developed with the help of two of my students,
Murray Wolinsky and Liguang Tian, over a period of approximately two
years. They are built on a foundation laid down in a paper written with
Surendra Singh, Reeta Vyas, and Perry Rice on waiting-time distributions
and wavefunction collapse in resonance fluorescence [Phys. Rev. A, 39,1200
A989)]. The ULB lecture notes contain my first serious attempt to give a
complete account of the ideas and their potential applications. I am grateful
to Professor Paul Mandel who, through his invitation to give the lectures,
stimulated me to organize something useful out of work that may, otherwise,
have waited considerably longer to be brought together.