The effects of photon correlation in a pumped resonant medium

Igor I. Gancheryonok, Inna V. Gaisyonok

When intense radiation (pumping) passes through a resonant medium, a change in polarization of another (probe) beam can take place. A pump wave induces optical anisotropy in an initially isotropic medium, which leads to dichroism and birefringence. Many papers have been concerned with the effect of resonant changes of the probe polarization slate; however, in most of these papers the authors have been limited by simplified cases with linearly or circularly polarized interacting beams.

S. Chopra, Himadri Bihari Bohidar, V. Harwalkar

Mahi R. Singh

The phenomenon of electromagnetically induced transparency has been studied when a four-level atom is located in a photonic band gap material. Quantum interference is introduced by driving the two upper levels of the atom with a strong pump laser field. The top level and one of the ground levels are coupled by a weak probe laser field and absorption takes place between these two states. The susceptibility due to the absorption for this transition has been calculated by using the master equation method in linear response theory. Numerical simulations are performed for the real and imaginary parts of the susceptibility for a photonic band gap material whose gap-midgap ratio is 21%. It is found that when resonance frequencies lie within the band, the medium becomes transparent under the action of the strong pump laser field. More interesting results are found when one of the resonance frequencies lies at the band edge and within the band gap. When the resonance frequency lies at the band edge, the medium becomes nontransparent even under a strong pump laser field. On the other hand, when the resonance frequency lies within the band gap, the medium becomes transparent even under a weak pump laser field. In summary, we found that the medium can be transformed from the transparent state to the nontransparent state just by changing the location of the resonance frequency. We call these two effects anomalous electromagnetically induced transparency.

Yu. A. Vdovin

Pablo Barberis-Blostein, Marc Bienert

The propagation of a pair of quantized fields inside a medium of three-level atoms in the $\ensuremath{\Lambda}$ configuration is analyzed. We calculate the stationary quadrature noise spectrum of the field after propagating through the medium in the case where the field has a general (but small) noise spectrum and the atoms are in a coherent population trapping state and show electromagnetically induced transparency. Although the mean values of the field remain unaltered as the field propagates, there is an oscillatory interchange of noise properties between the probe and pump fields. Also, as the field propagates, there is an oscillatory creation and annihilation of correlations between the probe and pump quadratures. We further study the field propagation of squeezed states when there is two-photon resonance, but the field has a detuning $\ensuremath{\delta}$ from atomic resonance. We show that the field propagation is very sensitive to $\ensuremath{\delta}$. The propagation in this case can be explained as a combination of a frequency-dependent rotation of maximum squeezed quadrature with an interchange of noise properties between pump and probe fields. It is also shown that the effect of the Doppler width in a squeezed state propagation is considerable.

S. Chopra, Himadri Bihari Bohidar, V. Harwalkar