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Resonance lineshapes in multi-level atomic systems

J.A. Hermann, S. Swain

Journal of Physics B Atomic and Molecular PhysicsOct 21, 19770 citations

Coherent control on absorption and dispersion in closely spaced transitions for a four-level system with three closely-spaced upper levels

Saswata Ghosh, Swapan Mandal

Under the Doppler free condition, a four-level system with three coherently prepared closely spaced upper levels coupled to a single electromagnetic field is being investigated for the absorptive and dispersive lineshapes. By using a perturbation method, the optical Bloch equations for the present four-level system are solved analytically to obtain the induced polarization and hence the spectral lineshapes. The field induced and field independent coherences appear automatically in the analytical expressions of the imaginary and real parts of the complex polarization. These field independent and field dependent coherences are the outcome of the quantum interference between the probability amplitudes of finding the atom in those energy levels. The phase sensitive field induced polarizations are extensively studied for two special conditions of the ground level populations. The influence of the closely spaced transitions on the quantum coherence and hence the subsequent effects on absorption despite inversion, electromagnetically induced transparency and on the ultrahigh index of refraction are discussed.Under the Doppler free condition, a four-level system with three coherently prepared closely spaced upper levels coupled to a single electromagnetic field is being investigated for the absorptive and dispersive lineshapes. By using a perturbation method, the optical Bloch equations for the present four-level system are solved analytically to obtain the induced polarization and hence the spectral lineshapes. The field induced and field independent coherences appear automatically in the analytical expressions of the imaginary and real parts of the complex polarization. These field independent and field dependent coherences are the outcome of the quantum interference between the probability amplitudes of finding the atom in those energy levels. The phase sensitive field induced polarizations are extensively studied for two special conditions of the ground level populations. The influence of the closely spaced transitions on the quantum coherence and hence the subsequent effects on absorption despite inversion, electromagnetically induced transparency and on the ultrahigh index of refraction are discussed.

Journal of Modern OpticsJun 16, 20103 citations

Formation of fast and slow decay modes in N-level systems coupled to one open channel

Frank-Michael Dittes, Hanns Ludwig Harney, I. Rotter

Physics Letters AMar 1, 199144 citations

Doppler-free absorptive signal lineshape of a four-level double λ-type system: Rabi splitting and two-photon effects

Saswata Ghosh, Swapan Mandal

Two electromagnetic fields (the stronger called the pump and the weaker called the signal) are allowed to interact with a four-level double λ-type system with two pairs of closely spaced levels. The present four-level system could also be viewed as an example of a double resonant system. Under the Doppler-free condition and using a semiclassical formulation of atom–field interaction, we derive the optical Bloch equations involving the said four-level system coupled to two external fields. These coupled optical Bloch equations are unsolvable in closed analytical form. In order to obtain the absorptive lineshapes, we use the usual perturbation method for getting the approximate analytical solution to the coupled optical Bloch equations for the density matrix elements. Through the off-diagonal complex density matrix elements, the introduction of phase angles between the levels participating in dipole-allowed transitions is automatic. It is shown that these phases are appreciable if the applied electromagnetic field is strong. For on-resonance pump conditions, we obtain the usual Rabi splitting. The effects of two-photon resonances are clearly shown for off-resonance pump conditions.Two electromagnetic fields (the stronger called the pump and the weaker called the signal) are allowed to interact with a four-level double λ-type system with two pairs of closely spaced levels. The present four-level system could also be viewed as an example of a double resonant system. Under the Doppler-free condition and using a semiclassical formulation of atom–field interaction, we derive the optical Bloch equations involving the said four-level system coupled to two external fields. These coupled optical Bloch equations are unsolvable in closed analytical form. In order to obtain the absorptive lineshapes, we use the usual perturbation method for getting the approximate analytical solution to the coupled optical Bloch equations for the density matrix elements. Through the off-diagonal complex density matrix elements, the introduction of phase angles between the levels participating in dipole-allowed transitions is automatic. It is shown that these phases are appreciable if the applied electromagnetic field is strong. For on-resonance pump conditions, we obtain the usual Rabi splitting. The effects of two-photon resonances are clearly shown for off-resonance pump conditions.

Journal of Physics B Atomic Molecular and Optical PhysicsJun 24, 20094 citations

An analytical study on absorptive lineshape of a driven N-type open four-level system: Quantum interference effects

Saswata Ghosh, Swapan Mandal

Optics CommunicationsJan 21, 20106 citations

Transitions in two-level systems at diffusion modulated isotropic interactions

И. В. Александров, L.G. Karamjan

Jan 1, 19730 citations

Effects of spontaneous decay on absorptive lineshape in closely spaced transitions of an open four level system

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