H. J. Carmichael

Time evolution and squeezing of the field amplitude in cavity QED

Summary form only given. Squeezing has traditionally been measured with a homodyne detector whose photocurrent output is frequency analyzed to quantify the noise reduction below the standard quantum limit. This measurement technique suffers from detection and propagation efficiencies. It seldom permits the complete reconstruction of the spectrum particularly when the frequency range is large. We have developed a new way to measure the squeezing spectrum through a third-order correlation function of the field. We correlate the detection of a photon with the record of the output of the photocurrent from a balanced homodyne detector. This method is a variant of the intensity correlation measurements that have shown non-classical features of the electromagnetic field.

Shot-to-shot fluctuations in the directed superradiant emission from extended atomic samples

We study collective spontaneous emission from arbitrary distributions of N two-state atoms using quantum trajectory theory and without an a priori single-mode assumption. Assuming a fully excited initial state, we calculate the angular distribution of the average intensity, focusing on pencil- and disc-shaped samples. The formalism is developed around an unravelling of the master equation in terms of source mode quantum jumps. A modified boson approximation is made to treat the many-atom case, where it is found that strong directional superradiance with shot-to-shot fluctuations occurs for a few hundred to a few thousand atoms.

Normal mode oscillation in the presence of inhomogeneous broadening.

We investigate effects of inhomogeneous broadening of excitons on normal mode oscillation in semiconductor microcavities using a coupled oscillator model. We show that inhomogeneous broadening can drastically alter the coherent oscillatory energy exchange process even in regimes where normal mode splitting remains nearly unchanged. The depth, frequency, and phase of normal mode oscillations of excitons at a given energy within the inhomogeneous distribution depend strongly on the energy separation between the exciton and the normal mode resonance. In addition, for an inhomogeneous broadened system, pronounced oscillations in the intensity of the optical field or the total induced optical polarization no longer imply a similar oscillatory coherent energy exchange between excitons and cavity photons.

Micromaser Revisited: Sub-Poissonian Fields from Poissonian Pumping

We perform quantum trajectory simulations of the micromaser/laser with Poissonian pump, lifting all restriction on the number of simultaneously interacting atoms. For mean numbers of intracavity atoms between zero and two, highly sub-Poissonian fields are obtained from the Poissonian pumping, with a Mandel (Q) parameter inside the cavity below (-0.6) under suitable conditions. Simulation of a Hanbury Brown and Twiss-type measurement performed on the cavity emissions recovers the intracavity value of the Mandel (Q) parameter from the intensity correlation function of the output photon stream.

Collective spontaneous emission from small assemblies of atoms

We study collective spontaneous emission from arbitrary distributions of N two-state atoms using quantum trajectory theory and without an a priori single-mode assumption. Assuming a fully excited initial state, we calculate the angular distribution of the average integrated intensity. We investigate the dependence of the angular distribution of emission on the geometry of the atomic distribution. The formalism is developed around an unravelling of the master equation in terms of source mode quantum jumps. A modified boson approximation is made to treat the many-atom case, where it is found that strong directional superradiance occurs for a few hundred to a few thousand atoms. In order to illustrate important differences between our model and single-mode models we consider shot-to-shot intensity fluctuations and angular correlations in the emitted intensity.

Effects due to the local fields and the phonons in atomic Bose-Einstein condensates: polariton approach

Summary form only given. The observation of atomic Bose-Einstein condensates (BECs) in magnetic and optical traps has stimulated theoretical investigation of the optical properties of these systems. Many of the current theories are based on the Heisenberg equations of motion for the radiation field and matter. These equations are nonlinear in the field operators and lead to an infinite hierarchy of equations for the atomic correlation functions. The hierarchy can be decoupled using an approximation. In an alternative development, the Heisenberg equations of motion have been simplified using an adiabatic approximation to eliminate the excited-state field operator. While some previous studies of BECs have employed the polariton approach, in these treatments neither the local field effects nor the polariton-phonon coupling are taken into account. Local field effects play an important role in a dense Bose gas (/spl rho//sup I/3//spl lambda//spl Lt/1) where, due to the resonance dipole-dipole interaction,the atoms respond to the electromagnetic field in a collective manner.In this contribution we examine the effects of both the local field and phonons using the polariton approach. The analysis is based on the quasiparticle concept.