Vacuum Induced Coherences in Radiatively Coupled Multilevel Systems

We show that radiative coupling between two multilevel atoms having near-degenerate states can produce new interference effects in spontaneous emission. We explicitly demonstrate this possibility by considering two identical V systems each having a pair of transition dipole matrix elements which are orthogonal to each other. We discuss in detail the origin of the new interference terms and their consequences. Such terms lead to the evolution of certain coherences and excitations which would not occur otherwise. The special choice of the orientation of the transition dipole matrix elements enables us to illustrate the significance of vacuum induced coherence in multi-atom multilevel systems. These coherences can be significant in energy transfer studies.Comment: 13 pages including 8 figures in Revtex; submitted to PR

Transition from antibunching to bunching for two dipole-interacting atoms

It is known that there is a transition from photon antibunching to bunching in the resonance fluorescence of a driven system of two two-level atoms with dipole-dipole interaction when the atomic distance decreases and the other parameters are kept fixed. We give a simple explanation for the underlying mechanism which in principle can also be applied to other systems. PACS numbers 42.50.Ar, 42.50FxComment: Submitted to Phys. Rev. A; 15 pages Latex + 4 figure

Master equations for effective Hamiltonians

We reelaborate on a general method for obtaining effective Hamiltonians that describe different nonlinear optical processes. The method exploits the existence of a nonlinear deformation of the su(2) algebra that arises as the dynamical symmetry of the original model. When some physical parameter (usually related to the dispersive limit) becomes small, we immediately get a diagonal effective Hamiltonian that represents correctly the dynamics for arbitrary states and long times. We apply the same technique to obtain how the noise terms in the original model transform under this scheme, providing a systematic way of including damping effects in processes described in terms of effective Hamiltonians.Comment: 10 pages, no figure

Potential benefits of Glycyrrhiza glabra (Liquorice) herb, its chemical make-up and significance in safeguarding poultry health: Current scientific knowledge

Positive results have been seen when bioactive components from herbal plants are added to poultry diets. Efficacy in feeding, digestion of nutrients, antioxidant health, immunological indices, and other factors can all be improved with the help of these additives, which in turn increases growth rates and improves poultry welfare. Several researchers have used sophisticated herbal formulae that included Glycyrrhiza glabra (Liquorice) as an ingredient. Epidemic illnesses, mainly in the respiratory, digestive, and immunological systems, pose the greatest threat to the poultry business. Flavonoids and glycyrrhizin are two of the bioactive compounds in Liquorice. The roots of this plant contain glycyrrhizin at concentrations of 1-9%, which has numerous pharmacological benefits, including anti-infectious, antioxidant, antiviral, and anti-inflammatory properties. Liquorice extracts are helpful in the treatment of multiple common illnesses. These include problems with the liver, the lungs, and the immunological system. Adding Liquorice to chicken diets improves their productivity in several ways, including fostering organ growth and stimulating digestion and appetite. Liquorice has many beneficial effects on birds, including helping them grow larger bodies, cleansing their systems, and protecting them from free radicals, bacteria, and inflammation. In this article, we'll look at the chemical make-up of liquorice herb, its role in protecting poultry health, and its recent applications and benefits

Two-photon resonance induced by the dipole-dipole interaction

The two-photon absorption by a pair of two-level atoms interacting with an incident field is examined. If the laser field is weak, then the existence of the dipole-dipole interaction-induced two-photon resonance follows from the higher-order Fermi golden rule. The effects of spontaneous emission and intense fields on the dipole-dipole interaction-induced two-photon resonance is studied using density-matrix methods. The presence of an intense field is shown to result in a significant enhancement of the two-photon resonance. Numerical results for the probability of simultaneous excitation of two atoms, for the atomic correlations, and for the radiated field intensity are presented

Microscopic approach to correlation-induced frequency shifts

A microscopic model for the origin of the source correlations responsible for Wolf shifts is proposed. To illustrate the main features of the phenomenon of these correlation-induced frequency shifts, a simple atomic system consisting of a pair of identical two-level atoms interacting with each other via the dipole-dipole interaction is considered. Effects of the finite temperature of the source are also included. For this microscopic model, the far-zone spectrum for two different experimental situations is calculated. The red and blue frequency shifts of the spectrum can be understood in terms of the dipole-dipole interaction. The magnitude of the shifts depends on the strength of the dipole-dipole interaction. The dependence of the frequency shifts on the temperature of the radiating source is also given

Squeezed-radiation-enhanced four-wave mixing in intense pumps

The nature of the nonlinear response of a quantum system in the presence of broadband squeezed radiation is examined. The relaxation of the system in the presence of squeezed radiation leads to enhancement of the four-wave-mixing signal

Quantum-statistical properties of a particle in a double-harmonic-oscillator potential: generation of Schrödinger-cat states

The quantum-mechanical double harmonic oscillator is proposed as a model for the generation of Schrödinger-cat states. To demonstrate this the quantum-statistical properties of the double oscillator in its ground state are examined. The nonclassical nature of this state and interference effects are analyzed. The squeezing properties of the double harmonic oscillator are calculated and compared with those of the ‘‘idealized’’ cat state. The behavior of the quasiprobability distribution function is also discussed