Entanglment properties of photon-added two-mode entangled coherent states are analyzed and analytical expression of the concurrence entanglement is obtained.The results show that the concurrence of the photon-added entangled coherent states is very sensitive to the superposition phase.Schemes for preparation of photon-added coherent states and photon-added two-mode entangled coherent states are also proposed.The preparation procession of the photon-added coherent states is that the photon-added coherent states are firstly tansformed into a superposition state of coherent state and vacuum state(the superposition coefficient is associated with amplitude of the coherent state),then by applying the interaction of atom inside high-Q cavity with a classical light,finally added coherent states of cavity field is prepared.Preparation of photon-added two-mode entangled coherent states of cavity fields is based on interaction of the flying atom with two cavity fields.
Entanglment properties of photon-added two-mode entangled coherent states are analyzed and analytical expression of the concurrence entanglement is obtained.The results show that the concurrence of the photon-added entangled coherent states is very sensitive to the superposition phase.Schemes for preparation of photon-added coherent states and photon-added two-mode entangled coherent states are also proposed.The preparation procession of the photon-added coherent states is that the photon-added coherent states are firstly tansformed into a superposition state of coherent state and vacuum state(the superposition coefficient is associated with amplitude of the coherent state),then by applying the interaction of atom inside high-Q cavity with a classical light,finally added coherent states of cavity field is prepared.Preparation of photon-added two-mode entangled coherent states of cavity fields is based on interaction of the flying atom with two cavity fields.
Polarization of light has been used extensively in quantum information processing, and quantum entanglement is essential to many areas of research, including quantum computing. Here we investigate the degree of polarization and the entanglement of a family of quantum states known as photon-added entangled coherent states. Such states could serve as means of entanglement distribution and quantum key distribution. Using the quantum Stokes parameters and the Q function, we demonstrate that, in general, the degree of polarization of two two-mode photon-added coherent states increases significantly with the number of added photons. And using the concurrence, we show that the amount of entanglement in this kind of superposition presents a behavior that is dependent on whether or not the number of added photons in each mode is the same.
Cavity quantum electrodynamics is the intersection of quantum physics and microcavity optics research. In this paper, we presented a two-mode cavity coupled to a classical field driven by N three-level atoms to prepare entangled coherent states based on cavity QED. In this scheme, we adopt the interaction between the three-level atoms and the two-mode optical cavity, The initial state of one optical field is an odd-even coherent state, while the initial state of another optical field is a coherent state. After considering the time evolution of the initial states with the system, we obtained the specific form of the time evolution of the quantum states and prepared the entangled coherent state successfully. We discussed and analysed some of the nonclassical properties of the optical field and quantum states, including the second-order correlation function and the Wigner function. The results show that when calculating the second-order correlation function, the photons are found to exhibit a sub-Poisson distribution at some points in time. In addition, when observing the Wigner function of the quantum states evolving with time, it is found that there is a negative part of the Wigner distribution at some moments, which implies that the quantum state exhibits nonclassical properties at these certain moments.
Polarization has been used extensively in quantum information processing, and quantum entanglement is essential to many areas of research, including quantum computing. Here we investigate the degree of polarization and the entanglement of a family of quantum states known as photon-added entangled coherent states. Such states could serve as means of entanglement distribution and quantum key distribution. Using the quantum Stokes parameters and the Q function, we demonstrated that, in general, the polarization of a superposition of two two-mode photon-added coherent states increases significantly with the number of added photons. And using the concurrence, we showed that the amount of entanglement in this kind of superposition presents a behavior that is dependent on whether or not the number of added photons on each mode is the same.
Base on the dispersive atom-cavity field interaction,the scheme for preparing the entangled coherent state is discussed.An experimentally feasible protocol for realizing entanglement diversion of the entangled coherent states by using a two-level atom interacting with caving fields is proposed.In this scheme,the entanglement between two coherent states,|α〉and|-α〉,with the same amplitude but a phase differenceπis utilized as the quantum channel.The process of the entanglement diversion is implemented by using the two-level atom interacting with caving fields,two-modes orthogonal states measurement and with the help of classical information.With the present development of cavity quantum electrodynamics (QED) techniques,the scheme can be achieved.
In this paper, we outline a scheme for the entanglement swapping procedure based on cavity quantum electrodynamics using the Jaynes–Cummings model consisting of the coherent and photon-added coherent states. In particular, utilizing the photon-added coherent states ([Formula: see text][Formula: see text][Formula: see text][Formula: see text], where [Formula: see text] is the Glauber coherent state) in the scheme, enables us to investigate the effect of [Formula: see text], i.e., the number of excitations corresponding to the photon-added coherent field on the entanglement swapping process. In the scheme, two two-level atoms [Formula: see text] and [Formula: see text] are initially entangled together, and distinctly two exploited cavity fields [Formula: see text] and [Formula: see text] are prepared in an entangled state (a combination of coherent and photon-added coherent states). Interacting the atom [Formula: see text] with field [Formula: see text] (via the Jaynes–Cummings model) and then making detection on them, transfers the entanglement from the two atoms [Formula: see text], [Formula: see text] and the two fields [Formula: see text], [Formula: see text] to the atom-field “[Formula: see text]-[Formula: see text]”, i.e., entanglement swapping occurs. In the continuation, we pay our attention to the evaluation of the fidelity of the swapped entangled state relative to a suitable maximally entangled state, success probability of the performed detections and linear entropy as the degree of entanglement of the swapped entangled state. It is demonstrated that, an increase in the number of excitations, [Formula: see text], leads to the increment of fidelity as well as the amount of entanglement. According to our numerical results, the maximum values of fidelity (linear entropy) 0.98 (0.46) is obtained for [Formula: see text], however, the maximum value of success probability does not significantly change by increasing [Formula: see text].
We introduce a class of the photon-added Bell-type entangled coherent states (PABECSs) obtained from Bell-type entangled coherent states by applying creation operators. We investigate their entanglement characteristics by analyzing the entropy of entanglement and discuss the influence of photon excitations on quantum entanglement. It is shown that applying a creation operator can increase the amount of entanglement. We also study the statistical properties of such states by discussing the behavior of the quasi-probability functions graphically. In addition, a possible scheme is presented to produce the PABECSs by using cavity quantum electrodynamics and quantum measurements.