In contrast to the free-space evolution of an atom governed by a multimode interaction with the surrounding electromagnetic vacuum, the evolution of a cavity-QED system can be characterized by just three parameters: (i) atom-cavity coupling strength
g, (ii) cavity relaxation rate $\ensuremath{\kappa}$, and (iii) atomic decay rate into the noncavity modes $\ensuremath{\gamma}$. In the case of an atom inserted into a planar resonator with an input beam coupled from the outside, it has been shown by Koshino [Phys. Rev. A 73, 053814 (2006)] that these three parameters are determined not only by the atom and cavity characteristics, but also by the spatial distribution of the input pulse. By an ab initio treatment, we generalize the framework of Koshino and determine the cavity-QED parameters of a coupled system of atom, planar (leaky) resonator, and input single-photon pulse as functions of the lateral profile of the pulse and the length of resonator. We confirm that the atomic decay rate can be suppressed by tailoring appropriately the lateral profile of the pulse. Such an active suppression of atomic decay opens an attractive route towards an efficient quantum memory for long-term storage of an atomic qubit inside a planar resonator.
In this paper we study the behavior of (laser--cooled) m--atoms trapped in a cavity interacting with a photon
... Cavity QED
... and attempt to solve the Schr{ö}dinger equation of this model in the strong coupling regime. In the case of m = 2 we construct Bell--Schr{\" o}dinger cat states (in our terminology) and obtain with such bases some unitary transformations by making use of the rotating wave approximation under new resonance conditionscontaining the Bessel functions, which will be applied to construct important quantum logic gates in Quantum Computation. Moreover we propose in the case of m = 3 a crucial problem to solve on Quantum Computation.
We investigate intensity cross-correlation functions for two cavity QED systems. These are a driven optical cavity containing a single two-level atom interacting with a single mode of the cavity field with quantized centre of mass motion, and a two-level atom in an optical parametric oscillator. We find analytic results in the weak driving field limit using quantum trajectory theory. We find large violations of inequalities that must be satisfied by classical fields. One of these inequalities is well known, g (2) ij (τ) ≤ √g (2) jj (0)g (2) jj (0), where i and j denote two modes of the field. We also derive a new inequality that cross-correlations must satisfy, |g (2) ij (τ) - 1| 2 ≤ |(g (2) ii (0) - 1)(g (2) jj (0) - 1)|. Large violations of classical inequalities and asymmetrical behaviour in delay time τ are found in complimentary regimes for the cavity QED system with quantized centre of mass motion. They always exist for the two-level atom inside an optical parametric oscillator.