We have studied the amplitude and temporal correlations of intensity fluctuations of multiply scattered light transmitted through a colloidal suspension. When the coherence length
lc of the incident light becomes comparable to the width of the probability distribution of photon-path lengths, both the amplitude and dynamics of intensity fluctuations become functions of
lc. In this article we present a simple theory that relates these coherence effects to the photon path-length distribution P(L). We have tested this theory using P(L) calculated from computer simulations and from the diffusion approximation, and find that our theory qualitatively accounts for the observed dependences on coherence length. Our results indicate when the effects of finite laser coherence must be taken into account in quasielastic multiple scattering. In the few-scattering regime of quasielastic multiple scattering, we find that the intensity autocorrelation function generally has a stretched-exponential form, and we discuss the origin of this behavior.
We theoretically investigate the scattering of few-photon light on Bose-Hubbard lattices using diagrammatic scattering theory. We explicitly derive general analytical expressions for the lowest-order photonic correlation functions, which we apply numerically to several different lattices. We focus specifically on nonlinear effects visible in the intensity-intensity correlation function and explain bunching and antibunching effects in dimers, chains, rings, and planes. The numerical implementation can be applied to arbitrary Bose-Hubbard graphs, and we provide it as an attachment to this publication.
IMeasurements of space-time correlations in the intensity of a beam of scattereq particles yield information about the scatterer.Goldberger and Watson have developed a theory of such measl~ementG appropriate to the case of ne~rly elastic scattering; in this paper we extend their theory to the case of inelastic scattering.The main result of our work is that under certain experimental conditions the correlated counting rate in an inelastic scattering experiment is of a form equivalent to the correlated counting rate for an incoherent beam of particles emitted by a source.This result applies, in particular, to Raman or Brillouin scattering of light by phonons in an extended target.However, estimates of the signal to noise ratio for this case indicate that it may not be possible to observe intensity correlations in Raman or Brillouin lines using presently available light sources. ABSTRACT OF PART IIThe coherent excitation of several atomic status by inelastic electron' scattering and their subsequent radia ti ve decay is considered.General expressions for the photon counting rate in a quantum beat experiment, and the total number of photons counted. in a le,vel crossing experiment are d.erived.The general results are used to calculate the phase of the oscillatory part of the photon counting rate in the Radeishi-Nierenberg quantum beat experiment.