Photon-added Bell-type entangled coherent state and some nonclassical properties

2009 ◽  
Vol 87 (12) ◽  
pp. 1233-1245 ◽  
Author(s):  
Hong-Chun Yuan ◽  
Heng-Mei Li ◽  
Hong-Yi Fan
Keyword(s):  
Coherent State ◽  
Quantum Electrodynamics ◽  
Coherent States ◽  
Cavity Quantum Electrodynamics ◽  
Quantum Measurements ◽  
Nonclassical Properties ◽  
Entangled Coherent State ◽  
Creation Operators ◽  
Photon Excitations ◽  
Entangled Coherent States

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.

The influence of excitation number of photon-added coherent state field on the entanglement swapping process

2017 ◽  
Vol 31 (27) ◽  
pp. 1750198 ◽  
Author(s):  
M. Soltani ◽  
M. K. Tavassoly ◽  
R. Pakniat
Keyword(s):  
Coherent State ◽  
Quantum Electrodynamics ◽  
Coherent States ◽  
Success Probability ◽  
Entanglement Swapping ◽  
Cavity Quantum Electrodynamics ◽  
Linear Entropy ◽  
Entangled State ◽  
Maximally Entangled State ◽  
Coherent Field

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].

Manipulation of Quantum Communication Channel via Two-Level Atom Interacting with Caving Fields

2014 ◽  
Vol 571-572 ◽  
pp. 469-472
Author(s):  
Xin Hua Cai ◽  
Jian Jun Nie
Keyword(s):  
Quantum Electrodynamics ◽  
Coherent States ◽  
Communication Channel ◽  
Quantum Communication ◽  
Cavity Quantum Electrodynamics ◽  
Entanglement Concentration ◽  
Field Interaction ◽  
Entangled Coherent State ◽  
Level Atom ◽  
Quantum Communication Channel

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 concentration of the entangled coherent states by using a two-level atom interacting with caving fields is proposed. In this protocol, the entanglement between two coherent states, and , with the same amplitude but a phase difference is utilized as the quantum communication channel. The process of the entanglement concentration is implemented by using a two-level atom interacting with caving fields and two-modes orthogonal states measurement. With the present development of cavity quantum electrodynamics (QED) techniques, the scheme can be achieved.

Photon-catalyzed optical coherent states generated via a non-degenerate parametric amplifier with quantum-optical catalysis

2020 ◽  
Vol 98 (2) ◽  
pp. 119-124 ◽  
Author(s):  
Hong-Chun Yuan ◽  
Xue-Xiang Xu ◽  
Heng-Mei Li ◽  
Ye-Jun Xu ◽  
Xiang-Guo Meng
Keyword(s):  
Coherent State ◽  
Wigner Function ◽  
Coherent States ◽  
Laguerre Polynomial ◽  
Photon Number ◽  
Parametric Amplifier ◽  
Normalization Factor ◽  
Nonclassical Properties ◽  
Quadrature Squeezing ◽  
Quantum Optical

We theoretically generate a kind of photon-catalyzed optical coherent states (PCOCSs) by heralded interference between any photons and coherent state via a non-degenerate parametric amplifier, which is also just a Laguerre polynomial excited coherent state. Based on obtaining the probability of successfully detecting them (also the normalization factor), the nonclassical properties of the PCOCSs are analytically investigated according to autocorrelation function, quadrature squeezing, and the negativity of the Wigner function. It is found that the nonclassicality depends on the amplitude of the coherent state, the catalysis photon number, and amplifier parameter. The negative volume of their Wigner function can be enlarged by increasing the catalysis photon number. These parameters may be effectively used to improve and enhance the nonclassical characteristics.

EFFECT OF DECOHERENCE ON FIDELITY IN TELEPORTATION OF ENTANGLED COHERENT STATES

2008 ◽  
Vol 06 (05) ◽  
pp. 1077-1092 ◽  
Author(s):  
H. PRAKASH ◽  
N. CHANDRA ◽  
R. PRAKASH ◽  
SHIVANI
Keyword(s):  
Coherent State ◽  
Coherent States ◽  
Low Noise ◽  
Entangled States ◽  
Average Fidelity ◽  
High Noise ◽  
Maximum Value ◽  
Entangled Coherent States ◽  
Suggested Modification

We consider the scheme proposed by Wang [Phys. Rev. A64 (2001) 022302] for teleporting bipartite entangled states, which is a superposition of coherent states |α,α〉 and |-α,-α〉, with our suggested modification [Phys. Rev. A75 (2007) 044305] and discuss the effect of decoherence on teleportation fidelity. We find that if no photons are counted in both final outputs, the minimum assured fidelity (MAF), which is the minimum of the fidelity for any arbitrary information), is still nonzero except for the case when there is no decoherence and the information is in even coherent state. For non-zero photon counts, MAF decreases with increase in |α|2 for low noise but in the case of high noise, it increases, attains a maximum value and then decreases with |α|2. We discuss the variation of average fidelity with |α|2 and show that it depends appreciably on the information for low values of |α|2 only.

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