http://www.iop.cas.cn/xwzx/kydt/201411/P020141128601608571942.pdf

Quantum cloning machines and the applications

We discuss the time evolution of entanglement, purity, and coherence of two non-interacting maximally entangled qubits in two different classical environmental configurations: bipartite and independent system–environment configuration. Gaussian noises, such as fractional Gaussian $$(\mathcal {F_G})$$
 and power-law (
 $$\mathcal {P_L})$$
 noise, are considered characterizing these environments. In particular, we are interested in exploring the dephasing effects in two qubits caused by the Gaussian noises in pure and mixed situations using entanglement witness, concurrence, purity, and decoherence measures. We notice both the noises in pure and in mixed forms are highly dephasing, and the bipartite quantum correlation, purity, and coherence eventually disappear after a finite interaction time. We notice that the current quantum phenomena decay faster under $$\mathcal {F_G}$$
 noise than under $$\mathcal {P_L}$$
 noise. Also, in independent system–environment configuration, the bipartite state is found to have slightly longer quantum correlation, purity, and coherence preservation than common environments, suggesting it more favourable for such quantum operations. For increasing values of the memory parameter of the $$\mathcal {F_G}$$
 noise, the entanglement, purity, and coherence become initially robust, defying the dephasing character of parameters of nearly all the noises. The wide spectrum of the pure $$\mathcal {P_L}$$
 noise can be readily exploited to design long preservation effects, especially by fixing the noise parameters to utmost low values. Also, the decay outlook induced by both noises is a monotonous function of time, with no entanglement sudden death and births observed.

Dynamics of bipartite quantum correlations and coherence in classical environments described by pure and mixed Gaussian noises

Quasi Bell states are introduced as a result of superposition of two-mode separable nonlinear coherent states. In this paper, we consider the nonlinearity function related to the harmonious states. To evaluate the effectiveness of these states in quantum information theory, nonclassical properties such as photon statistics, squeezing, and entanglement are studied. The entanglement of these states is examined by calculating the concurrence. According to our calculations, three of the introduced states are maximally entangled states. In addition, the cross-correlation function of the three maximally entangled states is less than 1 for all values of |α|2.

Nonclassical properties and entanglement of superposition of two-mode separable nonlinear coherent states

Nonlinear extensions of the single-mode squeezed vacuum and squeezed coherent states are constructed. Nonlinear squeezed coherent states (NLSCSs) are defined and special cases of these states are discussed. Two cases of the definition are considered for the unitary and non-unitary deformation operator functions. Some nonclassical properties of these states are discussed. The Glauber second-order coherence function is calculated. Analytical and numerical results for the quadrature component distributions for the NLSCSs are presented. The s-parameterized quasi-probability function, especially the Wigner function, is discussed.

A class of nonlinear squeezed coherent states

Entangled nonlinear coherent states of trapped ion motion and their non-classical properties

A class of even and odd nonlinear coherent states are introduced. The properties of some related states, including quadrature squeezing, antibunching effect and phase probability distribution, are studied.

A Class of Even and Odd Nonlinear Coherent States and Their Properties

Using the Pegg–Barnett formalism of phase operator, we obtain phase probability distributions of new even and odd nonlinear coherent states. It is shown that the distributions for the states are rather different, and unlike the case of ordinary even and odd coherent states the Pegg–Barnett distribution clearly reflects the different character of quantum interference in the case of the new even and odd coherent states.

Phase Properties of New Even and Odd Nonlinear Coherent States

One scheme for universal quantum multiple tele-flipping and tele-cloning of an arbitrary qubit is proposed. Our scheme combines three processes of quantum teleportation, optimal universal quantum flipping and optimal universal quantum cloning, and implements the task by consuming reduced entanglement resources. The key to the realization of this scheme is the construction of the particular 2 ( M + 1 ) -particle entangled state shared by the sender and the spatially separated receivers used as a quantum information channel. The entanglement structure of this multiparticle entangled state is analyzed.

Universal quantum multiple tele-flipping and tele-cloning of an arbitrary qubit

The emission spectrum of a two-level atom interacting with a single mode radiation field in the case of periodic oscillation coupling coefficient is investigated. A general expression for the emission spectrum is derived. The numerical results for the initial field in pure number stare are calculated. It is found that the effect of the coupling coefficient modulation on the spectral structure is very obvious in the case of a low modulation frequency and larger amplitude when the initial field is vacuum, which is potentially useful for exploring a modulated light source.

https://iopscience.iop.org/article/10.1088/0253-6102/60/2/13/pdf

Emission Spectrum Property of Modulated Atom-Field Coupling System

We prove that the nonorthogonal states randomly selected from a set can evolve into a linear superposition of multiple copies of anti-cloned state (an orthogonal state along with the original) with failure branch if and only if the input states are linearly independent. We derive a bound on the success probabilities of our machine. We show that probabilistic anti-cloning and multiple anti-cloning machines are special cases of our machine. The results for a single input state are also generalized into the case of several input copies of a state.

Jian Feng

Papers

A Class of Even and Odd Nonlinear Coherent States and Their Properties

Phase Properties of New Even and Odd Nonlinear Coherent States

Universal quantum multiple tele-flipping and tele-cloning of an arbitrary qubit

Emission Spectrum Property of Modulated Atom-Field Coupling System

Quantum Superimposing Multiple Anti-Cloning Machine