Nonclassical Properties of Superposition of Two Coherent States Shifted in Phase by 3π/2

We consider the quantum superposition of two coherent states shifted in phase by 3π/2 ｜α〉 and ｜ -iα〉, as well as special states that are characterized solely with respect to amplitude α. According to analysis of nonclassical properties such as oscillatory and sub-Poissonian distribution of photon numbers, photon antibunching, quadrature squeezing, and negativity of Wigner function, it is concluded that the considered superposition state is a nonclassical state. Also, the special state is found to exhibit even stronger nonclassical features when relative phase φ of the superposition is equal to the average photon number ｜α｜^2.     

Discussion on Maximally Entangled States of Two Coupled Two-Level Particles by Coherent State Approximation

We analyse the best condition for generating the maximally entangled states of the system containing two coupled two-level particles by the coherent approximation method beyond rotating wave approximation. It is found that the maximally entangled states are obtained when the detuning v and the strength Ω of driving laser satisfy the condition v/Ω= 2.5. The maximum average probability of entangled state pamax（v, Ω） has the best stability relying on v and Ω when vu ≈2Ω.     

Generation of W-Type Entangled Coherent States of Three-Cavity Fields by a Driving Classical Field

A scheme is proposed to generate the W-type entangled coherent states of three-cavity field. The scheme is based on the resonant atom-field interaction, thus the interaction time between the atom and the cavity is greatly reduced, which is important in view of decoherence. Furthermore, the scheme does not need accurate adjustment of the interaction time.     

Generation of Entangled Coherent States in Raman-Coupled Bose-Einstein Condensates

A method for producing entangled coherent states (ECSs) for atomic Bose-Einstein condensates (BECs) ispresented. The proposed method involves a BEC with three internal states and two classical laser beams ina three-level Lambda configuration. We show how to generate multi-state ECSs through properly manipulatingstrengths of these interactions and laser detunings. A maximally entangled coherent state is obtained explicitly.     

A Scheme for Preparation of W-Type Entangled Coherent State of Three-Cavity Fields

We present an experimental scheme to prepare the three-cavity W-type entangled coherent state in the context of dispersive cavity quantum electrodynamics. The discussion of our scheme indicates that it can be realized by current technology.     

Preparation and Decoherence of Two-Atom Entangled States in a Dissipative Cavity

We present a scheme for generating four pairs of two-atom Einstein Podolsky-Rosen （EPR） states using the simultaneous interaction of the two atoms with a single-mode cavity field under a large detuning condition. The influence of cavity dissipation on the prepared EPR states is investigated by means of the superoperator method and the state fidelity. It is shown that some kinds of the prepared EPR states are robust against cavity dissipation and the intensity of the field, and maintain their entanglement invariance, and the others are fragile and completely destroyed by the action of cavity dissipation and the intensity of the field in the long-time limit. Decoherence time of the fragile entangled states is extremely small for a typical cavity-QED experimental data.     

Properties of Entropy and Entanglement of Two—Mode Nonlinear Coherent States

In this communication ,two-mode nonlinear coherent states are reviewed and special cases are given,Starting from a three-level atom coupled to two modes of radiation with any form of nonlinearties of the two-mode fields.we derive a Raman-coupled effective Hamiltonian by a unitary transformation,evaluated perturbatively in coupling constants.We use the quantum entropy to measure the degree of entanglement in the time development of an effective two-level atom interacting with two-mode nonlinear-coherent states.The results show that the nolinearity effect yields the superstructure of atomic Radi oscillations and the effect of the Stark shift changes the quasiperiod of the field entropy evolution and entanglement between the particle and the field.A possible experimental test of a new effect is proposed.     

Nonclassical Properties in the Resonant Interaction of a Three Level A-type Atom with Two-mode Coherent state

A potential scheme is proposed to deterministically generate complete sets of entangled photons in the context of cavity quantum electrodynamics （QED）. The scheme includes twice interactions of atoms with cavities, in which the first interaction is made in two-mode optical cavities and the second one exists in a microwave cavity. In the optical cavities the atoms are resonant with the cavity modes, while the detuned interaction of the atoms with a singlemode of the microwave cavity is driven by a classical field. The favorable features of our scheme include ： （ 1 ） it is very straightforward in implementation because we carry out the scheme by only sending atoms through the cavities. The requirement for the implementation is very close to the reach of current cavity QED techniques. （2） The com- plete set of the entangled two- or more-photon states can be generated deterministically by our scheme, and the implementation time remains constant with the size of the entangled photon states. （3） Our scheme is more efficient than previous proposals with cavities, and the generated photons may be collected much more efficiently, due to cavities, than previous proposals by spontaneous emission.     

Generation of High-Dimensional Photon Entangled Coherent States in Double Electromagnetically Induced Transparency System

We present an approach to generate high-dimensional entangled coherent states between photons by using a dense atomic system in a double electromagnetically induced transparency state. The system under our consideration involves an atomic configuration with six internal states, two weak quantized probe lasers, and two strong classical coupling lasers. We show how to generate high dimensional entangled coherent states between the two probe lasers.     

Quantum Fisher Information of Entangled Coherent States in a Lossy Mach–Zehnder Interferometer

We give an analytical result for the quantum Fisher information of entangled coherent states in a lossy Mach-Zehnder interferometer recently proposed by Joo et al., [Phys. Rev. Lett. 107 （2011） 083601]. For small loss of photons, we find that the entangled coherent state can surpass the Heisenberg limit. Phrthermore, the formalism developed here is applicable to the study of phase sensitivity of multipartite entangled coherent states.     

EPR Entangled States for Bipartite Kinematics and New Bosonic Representation of SU（2） Algebra

We find that the Einstein-Podolsky-Rosen (EPR) entangled state representation descr/bing bipartite kinematics is closely related to a new Bose operator realization of SU(2) Lie algebra. By virtue of the new realization some ttamiltonian eigenfunction equation can be directly converted to the generalized confluent equation in the EPR entangled state representation and its solution is obtainable. This thus provides a new approach for studying dynamics of angular momentum systems.     

Generation of Three-Dimensional Entangled States for Two Atoms Trapped in Different Cavities

We propose a scheme for generating three-dimensional entangled states for two atoms trapped in two separate cavities. The scheme is based on the detection of photons leaking from the cavities after the atom-cavity interaction. The scheme is useful for the test of quantum nonlocality and quantum information processing.     

Effect of thermal environment on quantum nonlocality of superposition of two coherent states (π/2 out of phase)

Recently we studied the tests of Bell-type inequalities with superposition of two coherent states (π/2 out of phase) [D. K. Mishra, Acta Phys. Pol. A. 123, 21 (2013)]. Here, we study the effect of thermal environment on the Bell-CHSH inequality. As the state interacts with the thermal environment, the time evolution of the linear entropy to study the purity loss in the state has also been examined.     

The influence of interfacial barrier engineering on the resistance switching of In2O3：SnO2/TiO2/In2O3：SnO2 device

The I-V characteristics of In2O3：SnO2/TiO2/In2O3：SnO2 junctions with different interracial barriers are inves- tigated by comparing experiments. A two-step resistance switching process is found for samples with two interfacial barriers produced by specific thermal treatment on the interfaces. The nonsynchronous occurrence of conducting filament formation through the oxide bulk and the reduction in the interracial barrier due to the migration of oxygen vacancies under the electric field is supposed to explain the two-step resistive switching process. The unique switching properties of the device, based on interracial barrier engineering, could be exploited for novel applications in nonvolatile memory devices.     

Effect of La Concentration on the Kinetics of the Induced Phase Transition in PbMg1/3Nb2/3O3–25PbTiO3 Transparent Ceramics

Physics of the Solid State - The effect of La concentration on the kinetic character of the induced phase transition in PbMg1/3Nb2/3O3–25PbTiO3 ferroceramics is studied. Below the...     

Phase Diagrams of Thin Disordered Films Based on HTSC YBa2Cu3O7 – x in External Magnetic Fields

Physics of the Solid State - An unusual decrease in the slope of the upper critical field near Tc0 at a gradual increase in the ion implantation dose has been experimentally observed in narrow...     

Investigation on Nonradiative Decay of the Er^3＋^4I13/2 → ^4I15/2 Transition in Different Tellurite Glass Matrix

Three kinds of Er^3＋-doped tellurite glasses with different hydroxyl groups are prepared by the conventional melt-quenching method. Infrared spectra are measured to estimate the exact content of OH^- groups in samples. The maximum phonon energy in glasses are obtained by measuring the Raman scattering spectra. The strength parameters Ωt （t = 2, 4, 6） for all the samples are calculated and compared. The nonradiative decay rate of the Er^3＋ ^4I13/2 → ^4I15/2 transition are calculated for the glass samples with different phonon energy and OH^- group contents. Finally, the effect of OH^- groups on fluorescence decay rate of Er^3＋ is analysed, the constant KOH-Er of TWN, TZPL and TZL glasses are calculated to be 9.2 × 10^-19 cm^4s^-1, 5.9 × 10^-19 cm^4s^-1, and 3.5 × 10^-19 cm^4s^-1, respectively.