The temporal evolution of the degree of entanglement between two atoms in a system of the binomial optical field interacting with two arbitrary entangled atoms is investigated. The influence of the strength of the dipole–dipole interaction between two atoms, probabilities of the Bernoulli trial, and particle number of the binomial optical field on the temporal evolution of the atomic entanglement are discussed. The result shows that the two atoms are always in the entanglement state. Moreover, if and only if the two atoms are initially in the maximally entangled state, the entanglement evolution is not affected by the parameters, and the degree of entanglement is always kept as 1.
We investigate spontaneous emission properties and control of the zero phonon line(ZPL) from a diamond nitrogen–vacancy(NV) center coherently driven by a single elliptically polarized control field. We use the Schr¨odinger equation to calculate the probability amplitudes of the wave function of the coupled system and derive analytical expressions of the spontaneous emission spectra. The numerical results show that a few interesting phenomena such as enhancement,narrowing, suppression, and quenching of the ZPL spontaneous emission can be realized by modulating the polarizationdependent phase, the Zeeman shift, and the intensity of the control field in our system. In the dressed-state picture of the control field, we find that multiple spontaneously generated coherence arises due to three close-lying states decaying to the same state. These results are useful in real experiments.
The evolution of a pure coherent state into a chaotic state is described very well by a master equation, as is validated via an examination of the coherent state's evolution during the diffusion process, fully utilizing the technique of integration within an ordered product(IWOP) of operators. The same equation also describes a limitation that maintains the coherence in a weak diffusion process, i.e., when the dissipation is very weak and the initial average photon number is large. This equation is dρ/dt =-κ[a+aρ- a+ρa- aρa++ ρaa+]. The physical difference between this diffusion equation and the better-known amplitude damping master equation is pointed out.
We find the time evolution law of a negative binomial optical field in a diffusion channel. We reveal that by adjusting the diffusion parameter, the photon number can be controlled. Therefore, the diffusion process can be considered a quantum controlling scheme through photon addition.
