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A scheme for generating two-mode photon-added SU(2) coherent state by means of conditional measurement is proposed. Feeding three uncorrelated Fock states into three input ports of two cascade placed lossless beam splitters respectively and counting photons in one of the output channels, the conditional state in the other two output channels is a two-mode photon-added SU(2) coherent state. The quantum nonlocality property for this state is investigated using parity measurement.

An analytical expression of emission spectrum for Λ -type three-level atom interacted with two-mode cavity field is given. The characters of the emission spectrum for the field in photon number state, coherent state and SU(2) coherent state are exhibited. The effects of the atomic initial state, the field property on the time-dependent physical spectrum are analyzed.

The modification of the Autler-Townes spectrum of a V-type three-level atom driven by a strong coherent field and a weak stochastic field with a wide bandwidth is studied. It is found that the lineshape of the probe absorption spectrum varies drastically with the changing of the frequency difference between the coherent field and the stochastic one. The probe beam can be amplified due to the effect of the stochastic field and this amplification can be enhanced due to the quantum interference induced by the stochastic field. (C) 2002 Elsevier Science B.V. All rights reserved.

The time evolution of nonlocality for atom-field entangled state in the system of a two-level atom interacting dispersively C with a single-mode field in a dissipative cavity is investigated. It is found that, if the cavity dissipation is very weak, the atom-field state can exhibits nonlocality periodically. The rapidity of the loss of the initial quantum nonlocality depends on the amplitude of the two coherent states and the cavity damping constant K. The stronger the field is and the larger the constant K, the more rapidly the nonlocality decreases. (C) 2001 Elsevier Science B.V. All rights reserved.

We have studied the spectrum of spontaneous emission of a V-configuration three-level atom, whose two upper levels are linked by a classical driving field and their energy spacing is much larger than the spontaneous emission widths. It is shown that the spectrum can be controlled by the driving field and peaks with subnatural linewidth can be produced.

The effect of the laser linewidth on the resonance fluorescence spectrum of a two-level atom is revisited. The novel spectral features, such as hole-burning and dispersive profiles at line centre of the fluorescence spectrum are predicted when the laser linewidth is much greater than its intensity. The unique features result from quantum interference between different dressed-state transition channels., 4 pages & 4 figures, Phys. Lett. A, (in press)

We have studied atomic coherent population trapping in a ⋀-configuration three-level atom interacting with a two-mode quantized field mediated by two-photon processes. The states of the field trapping the atom in its two lower states are obtained, and the nonclassical properties of these states are discussed.

A generalized laser-induced continuum structure system consisting of an atom with two bound states and two sets of flat atomic continuum states interacting with four laser fields is proposed. The effects of the relative phase of the four lasers on the photoionization properties are investigated.

We have studied the steady-state behavior of a V configuration three-level atom driven by a single-mode laser field in a broadband squeezed vacuum bath. The influences of the bath and the relative directions of the atomic dipole moments are discussed.

The atomic coherent trapping in a system of two-level atoms interacting with a single-mode coherent field has been investigated. The conditions under which the atomic coherent trapping can take place and the time evolution of the atomic populations have also been analyzed.