Jagdish Rai

A dissipative quantum mechanical beam-splitter.

A dissipative beam-splitter (BS) has been analyzed by modeling the losses in the BS due to the excitation of optical phonons. The losses are obtained in terms of the BS medium properties. The model simplies the picture by treating the loss mechanism as a perturbation on the photon modes in a linear, non-lossy medium in the limit of small losses, instead of using the full field quantization in lossy, dispersive media. The model uses second order perturbation in the Markoff approximation and yields the Beers law for absorption in the first approximation, thus providing a microscopic description of the absorption coecient. It is shown that the fluctuations in the modes get increased because of the losses. We show the existence of quantum interferences due to phase correlations between the input beams and it is shown that these correlations can result in loss quenching. Hence in spite of having such a dissipative medium, it is possible to design a lossless 50-50 BS at normal incidence which may have potential applications in laser optics and dielectric-coated mirrors.

Transfer of non-classical properties in dual channel directional coupler

In this paper we analyze the quantum uncertainties and the photon statistics in the interaction between the two modes of radiation by treating them as coupled harmonic oscillator with the motivation of controlling quantum properties of one light beam by another. Under the rotating wave approximation (RWA) we show that if initially one of the modes is coherent and the other one squeezed, then the squeezing and non-Poissonianness of the photon statistics can transfer from one mode to the other. We give a parametric study of these properties depending upon interaction time and the degree of initial squeezing in one of the modes.Abstract Quantum uncertainties of the quadratures and the photon statistics are analyzed in the coupling interaction between two modes of radiation via a dual channel directional coupler. The motivation of this work is to control the quantum properties of one light beam by another. Under the rotating wave approximation we show that if one of the modes is coherent (classical) and the other one squeezed, then the squeezing and non-Poissonianness of the photon statistics can be induced in the coherent mode. It is also shown that the transferred squeezing and non-classical number statistics in the second mode is of a new type. In the affected mode the squeezed quadrature remains squeezed, whereas the other quadrature is anti-squeezed, throughout except at the times where both of them return to a coherent value. The photon number of the affected mode shows both sub-Poissonian and super-Poissonian statistics as time evolves.

Gain enhancement in lasing without inversion in an optically dense medium

Abstract Under suitable conditions, a Λ-type three-level system driven by a strong pump field on one of the transitions and interacting with a weak probe field exhibits gain in a probe amplitude without population inversion [A. Imamoglu, J.E. Field and S.E. Harris, Phys. Rev. Lett. 66 (1991) 1154]. We present a theory of gain without population inversion in an optically dense medium where the local-field corrections that arise due to near dipole-dipole interactions, become significant. Numerical calculations that account for strong pump induced nonlinearities in the dense medium, show evidence of a large enhancement of the probe gain without population inversion in an optically dense medium.

Experimental investigation of source correlations in the time domain

Abstract An experimental study of source correlation effects in the time domain providing experimental evidence for splitting of the spectral line is reported. Evidence of the splitting is also provided from the available data on the structure of the intensity correlation function for the laser beam operating near its threshold of oscillation.

Wigner Distribution Function for Optical Fields and its Application to the Detection of Squeezed States

The Wigner Distribution Function (WDF) is currently receiving attention as a powerful tool in optics1 and communication theory. Several schemes have been prepared for the optical implementation of WDF2In this paper we obtain the WDF for optical fields and propose a scheme for the detection of squeezed states using the optical implementation of WDF. The WDF in optics is defined in terms of the complex field amplitude Ф (x,t) as

Quantum Statistical Analysis of Superflourescence and Amplified Spontaneous Emission in the Dense Atomic Systems

Cooperative emission from a collection of atoms prepared in an initial state of complete inversion has been studied extensively in the past. In the studies, where propagational effects are involved, the assumption has been made that the density range is such that there are never more than a fraction of an atom per cubic resonance wavelength on the average. The effects of the induced dipole-dipole interaction among the atomic constituents is, therefore, negligible and plays no role. The situation is quite different, however, when the density range includes a regime characterized by a large average number of atoms per cubic resonance wavelength. Under such conditions, effects of the induced dipole-dipole interaction among neighboring atoms cannot be ignored. Recently, it has been shown that the analysis of the effects of such interatomic interaction in a dense system can lead to several kinds of new and novel nonlinear effects1,2. Results for two-level systems indicate that a set of modified Maxwell-Bloch equations is obtained where the effects of the dipole-dipole interactions appear as a nonlinear inversion-dependent renormalization of the atomic resonance frequency.

Theory and Photon Statistics of a Free Electron Laser

We have carried out an analysis of free electron lasers (FEL) by integrating the equations of motion for the field annihilation and creation operators as well as those for the electron position and momentum operators. We use the non-relativistic FEL Hamiltonian in the Bambini-Renieri frame, which is a moving frame with the wiggler and laser frequencies ωw=ωL=ω We work in the single particle, low gain, weak beam picture. In this paper we study the properties of radiation emitted by the FEL interaction.