Hyunchul Nha

Cavity-damping-induced transitions in a driven atom–cavity system

We investigate the fluorescence spectrum of a two-level atom in a cavity when the atom is driven by a classical field. We show that forbidden dipole transitions in the Jaynes-Cummings ladder structure are induced in the presence of cavity damping, which deteriorates the degree of otherwise perfect destructive interference among the transition channels. With the larger cavity decay, these transitions are more enhanced.

Stochastic initiation of superradiance in a cavity: Decoherence through pseudospin exchange

We study superradiance from a fully inverted medium in the presence of two channels for atomic relaxation. Spontaneous emission from individual atoms is included and competes with the collective emission responsible for superradiance. We compare exact results within the quantum trajectory formalism with a previous approximation [J. P. Clemens and H. J. Carmichael, Phys. Rev. A 65, 023815 (2002)] which neglects the reexcitation of an atom after it spontaneously emits. The approximation underestimates the decoherence during the second half of an emitted pulse.

Squeezing by damping in a driven coupled-oscillator system

We investigate a coupled quantum-oscillator system where a harmonic oscillator is coupled to all ancillary oscillator being pumped. The squeezing effect. is enhanced as the damping rate of the harmonic oscillator is increased to some extent.

Atomic wave packet dynamics in a standing wave quantum field

We analyze a cavity-QED single atom detection system, in the viewpoint of the momentum-quantized quantum trajectory theory. We find that the detection efficiency is not sensitive to the individual atomic trajectory for reasonably slow atoms.