Bump in the variance of long intensity (A)

P. R. Berman, A. Kuzmich

The interaction of a single-photon pulse of radiation with an atom or an ensemble of atoms is studied using a source-field approach. The atom-field interaction is weak insofar as it can be treated in lowest, nonvanishing order of perturbation theory. The output field intensity and second-order correlation function of the field are calculated. It is shown that, even when any modification of the atomic dynamics produced by the incident field is neglected, as a function of the time delay $\ensuremath{\tau}$ between the incident field pulse and the field radiated by the atom(s), there is a ``bump'' in the time-integrated second-order correlation at $\ensuremath{\tau}=0$. The increase in coincidence counts for $\ensuremath{\tau}=0$ can be interpreted in terms of Hanbury Brown and Twiss--type interference. By looking at the field intensity, we show that the bump has no direct relation with stimulated emission---it occurs even when the input field is attenuated. In recent down conversion experiments, an increase in coincidence counts has been attributed to stimulated emission---we comment on the validity of such an interpretation in light of our results.

Edgard Elbaz

Chunhong Cao

The long-time behavior of squeezing of intense coherent light is studied with off-resonance Jaynes-Cummings model. The interaction between field and atom includes both one-photon transition type and two-photon transition type. The analytical formulae for quadrature variances are obtained. In one-photon transition case, small detuning only has small effect on squeezing. For two-photon transition, however, the situation is quite different. No squeezing will occur in resonance case. Only detuning can cause squeezing. Then a series of minimum appear in the suppressed quadrature variance during time evolution. In Urge N limit this se-ries tends to zero.

Ignazio Francesco Licata, Davide Fiscaletti

Chang-qi Cao, Ding Xiao-hong, 北京大学物理系,北京100871

The long-time behavior of squeezing of intense coherent light is studied with off-resonance Jaynes-Cummings model. The interaction between field and atom includes both one-photon transition type and two-photon transition type. The analytical formulae for quadrature variances are obtained. In one-photon transition case, small detuning only has small effect on squeezing. For two-photon transition, however, the situation is quite different. No squeezing will occur in resonance case. Only detuning can cause squeezing. Then a series of minimum appear in the suppressed quadrature variance during time evolution. In Urge N limit this se-ries tends to zero.