In this paper, we study the nonclassical properties of the electromagnetic field resulting from the interaction of a three-level ∧-type atom with a two-mode field initially in the coherent state, such as squeezing properties and sub-Poisson statistics. We show that the squeezing can be enhanced by selective atomic measurement.
Nonclassical properties of a two-mode field initially in an SU(2) coherent state resonantly interacting with a three-level Λ-type atom are investigated by means of the quantum theory and numerical calculations. The dependence of the nonclassical properties on the total photon number of the two-mode, the partition parameter and the coupling constant is discussed for three cases: (1) no state-selective atomic measurement; (2) direct state-selective atomic measurement; and (3) state-selective atomic measurement after the application of a classical field. The results indicate that when the total photon number of the two-mode is increased or the state-selective measurement is performed on the atom, the difference squeezing of two-mode is distinctly enhanced; and when the partition parameter is decreased or the state-selective measurement is performed on the atom after the application of a classical field, the average intensity of the sub-Poisson statistic distribution of mode a is reduced and that of mode b is enhanced; when the total photon number of the two modes is increased or the direct state-selective measurement is performed on the atom, the anti-correlation character between the two modes is preserved, but the average intensity of the anti-correlation is reduced; and when the direct state-selective measurement is performed on the atom, the Cauchy-Schwartz inequality is violated.
We consider the case that one of the two initially entangled V-type three-level atoms is injected into a two-mode cavity and resonantly interacting with a two-mode field initially in a SU(2) coherent state.Nonclassical properties of the two-mode correlated field are investigated numerically.The influences of the state-selective measurement of the atom outside the cavity,the total photon number of the two modes,and the partition parameter on the difference squeezing,the Cauchy-Schwarz inequality,the mode-correlation properties,and the photon number distribution are discussed.The results indicate when the state-selective measurement is performed on the atom outside the cavity or the total photon number is increased,the difference squeezing and the sub-Poisson distribution of the photon number of mode a is distinctly enhanced,but the anti-correlation between the two modes is distinctly reduced.
We study the non-classical properties of the single-mode electro-magnetic field resulting from the interaction of a Ξ-type three-level atom initially in the coherent state, such as squeezing properties and sub-Poisson statistics.We show that if there are more photons in the cavity, the squeezing will appear earlier and be stronger under the same state, but the sub-Poisson statistics will be weaker, while sub-Poisson statistics and squeezing are more pronounced after the selective atomic measurement.
Quantum statistic properties of a two-mode field initially in a coherent state resonantly interacting with a three-level V-type atom are investigated by means of the quantum theory and numerical calculations.The dependence of the sub-Poisson statistics,the coherent properties of two-mode cavity field,photon bunching and anti-bunching,and the violations of Cauchy-Schwarz inequality on the average photon number of the cavity mode,the coupling constant and the interaction time is discussed in three cases:(1) no state-selective measurement on the atom;(2) direct state-selective measurement on the atom;(3) state-selective measurement on the atom after the application of a classical field.The results indicate,when the state-selective measurement is performed on the atom,the sub-Poisson statistic properties is distinctly enhanced,the anti-correlative degree between two-mode is distinctly deadened,and the Cauchy-Schwarz inequality is always violated;the mode a anti-bunching exhibits when the state-selective measurement is performed on the atom and the average photon number difference of the two cavity modes is large.