Narrow Results

We construct coherent state of the effective mass harmonic oscillator and examine some of its properties. In particular closed form expressions of coherent states for different choices of the mass function are obtained and it is shown that such states are not in general x - p uncertainty states. We also compute the associated Wigner functions.

In this paper, the representation of A_κ(2) algebra given by Daoud and Kibler [J. Phys. A43, 115303 (2010); J. Phys. A45, 244036 (2012)] is generalized to the multi-mode case. The representation of the multi-mode extension of A_κ(2) algebra, which is called A_κ(d) algebra, is also obtained. The positivity condition of the energy spectrum and the coherent state are also investigated for A_κ(d) algebra.

Using shape invariance property we construct coherent state for a class of potentials containing Scarf I and its extensions, the solutions of the latter being given in terms of the recently discovered Jacobi-X_l type exceptional polynomials. It is shown that the coherent state possesses the property of resolution of unity and exhibits sub-Poissonian behavior. We then investigate the coherent state of Scarf I potential and its l = 1 extension in some detail to understand the similarities (and differences) between the exceptional orthogonal polynomials and their classical counterparts.

Based on the coherent state (S1) and the operator ${(x{a}^{†}+ya)}^m$, we induce other three quantum states (here we abbreviate them as S2, S3 and S4). S2 is obtained by operating the operator on S1 directly. S3 is an orthogonal state of S1 constructed from the orthogonalizer relevant with that operator. S4 is a continuous-variable (CV) qubit state superposed from S1 and S3. We study and compare the mathematical and physical properties of such four quantum states. We demonstrate some statistical properties for S1–S4, including the mean photon number (MPN), anti-bunching effect, quadrate squeezing, photon number distribution, Husimi Q-function and Wigner function. The numerical results show some interesting non-classical characters for such states. It is worthy to note that the photon-added coherent state introduced by Agarwal and Tara is only a special case of our considered states.

The physical properties of the SO(2, 1) coherent state for the Coulomb problem are discussed in this paper. We find that the coherent state, for which the minimum uncertainty relation holds, has a nonvanishing geometric phase factor, and also is approximately nonspreading in the classical limit of the high excitation of angular momentum.

We present a new approach to finding multipartite entangled state representation by decomposing normally ordered Gaussian-form operator in completeness relation, the technique of integration within an ordered product (IWOP) of operators is essential in this searching.

We study amplitude-squared squeezing in interaction of coherent light with a nonlinear Kerr medium modelled as an anharmonic oscillator with interaction Hamiltonian H = ½ λ a⁺²a², where λ is proportional to χ⁽³⁾ of the nonlinear medium and a is annihilation operator for the interacting field. We find the squeezing parameter S ( τ, r) in terms of a dimensionless interaction time τ = λ t and Kerr parameter r, which is product of, τ and the average number of photons and obtain almost complete amplitude-squared squeezing (i.e., S ≈ 0) for very small interaction time and very large intensity of the interacting light. We optimize squeezing parameter S ( τ, r) by an analytic estimation assuming high intensity of the interacting light and realistic values of Kerr nonlinearity following J.Bajer et al. [Czech. J. Phy. 52, 1313 (2002)] and obtain a scaling law for optimal amplitude-squared squeezing with minimum value S_min, at r = r_min for a given τ. The validity of the scaling law is checked numerically and analytically in the region of realistic values of Kerr nonlinearity and intensity of the interacting light.

The coherent entangled state |β, x〉 is proposed in Fock space, which exhibits both the properties of the coherent and entangled states. The |β, x〉 makes up a new quantum mechanical representation, and the completeness relation of |β, x〉 is proved by virtue of the technique of integral within an ordered product of operators. The corresponding Schmidt decomposition of |β, x〉 is investigated. Furthermore, a feasible experimental scheme of |β, x〉 is presented, and generalized P-representation is constructed in the coherent entangled state |β, x〉.

We develop a basic formulation of the spin (SU(2)) coherent state path integrals based not on the conventional highest or lowest weight vectors but on arbitrary fiducial vectors. The coherent states, being defined on a 3-sphere, are specified by a full set of Euler angles. They are generally considered as states without classical analogues. The overcompleteness relation holds for the states, by which we obtain the time evolution of general systems in terms of the path integral representation; the resultant Lagrangian in the action has a monopole-type term à la Balachandran et al. as well as some additional terms, both of which depend on fiducial vectors in a simple way. The process of the discrete path integrals to the continuous ones is clarified. Complex variable forms of the states and path integrals are also obtained. During the course of all steps, we emphasize the analogies and correspondences to the general canonical coherent states and path integrals that we proposed some time ago. In this paper we concentrate on the basic formulation. The physical applications as well as criteria in choosing fiducial vectors for real Lagrangians, in relation to fictitious monopoles and geometric phases, will be treated in subsequent papers separately.

In this letter, a procedure is proposed for reconstructing the motional quantum state of N trapped ions. Unlike other previous schemes, the present scheme works in the dispersive regime in the presence of dissipation. In our scheme, we show that it is possible to directly measure the quasiprobability distribution function corresponding to the motional coherent state in a trapped-ion system subjected to dissipation. We also provide an example of a motional Schrödinger cat state reconstruction to exemplify our procedure.

Squeezing in four wave mixing process was studied recently using perturbation method by Giri and Gupta [D. K. Giri and P. S. Gupta, J. Opt. B: Quantum Semiclass. Opt.6 (2004) 91.] We reexamine this using a coherent intense pump mode and with a much better approximation which results in validity of our results for much larger interaction times. We find that for the range of phase where these authors obtained squeezing, only a small squeezing is obtained for a brief period but larger squeezing at large times is obtained in the other range of phase. We also obtain larger amplitude squared squeezing.

We study polarization squeezing of a light beam initially in the coherent state using the nonlinear interaction Hamiltonian $H=k({â}_x^{†2}+{â}_x^2)$. For the degree of polarization squeezing, we use a definition written in the final form by the authors and also used in earlier papers. We find that the polarization squeezing can be very high and the degree of polarization squeezing can be less than unity by a very small amount. We achieve the polarization squeezing even for very low beam intensity under some conditions involving phase angles in the polarization modes.

We observe the polarization squeezing in the mixture of a two mode squeezed vacuum and a simple coherent light through a linear polarization beam splitter. Squeezed vacuum not being squeezed in polarization, generates polarization squeezed light when superposed with coherent light. All the three Stokes parameters of the light produced on the output port of polarization beam splitter are found to be squeezed and squeezing factor also depends upon the parameters of coherent light.

A three-dimensional harmonic oscillator is studied in the context of generalized coherent states. We construct its squeezed states as eigenstates of linear contribution of ladder operators which are associated to the generalized Heisenberg algebra. We study the probability density to show the compression effect on the squeezed states. Our analysis reveals that squeezed states give us some freedom on the precise knowledge of position of the particle while maintaining the Heisenberg uncertainty relation minimum, squeezed states remains squeezed states over time.

An orthogonal state of coherent state is produced by applying an orthogonalizer related with Hermite-excited superposition operator $H_m(x{a}^{†}+ya)$. Using some technique, we cleverly deal with the normalization and discuss the nonclassical and non-Gaussian characters of the orthogonal state. The analytical expressions for the Wigner functions of the orthogonal state are derived in detail. Numerical results show that the orthogonal state will exhibit its richly nonclassical and non-Gaussian character by changing the interaction parameters.

In this paper, using the principle of quantum state superposition, we report a nonclassical quantum state which is constructed by repeatedly operating the number operator on the coherent state. Nonclassical effects of this state are discussed by photon-number distribution, sub-Poissonian statistics, anti-bunching and negativity of Wigner function and squeezing effect. Our work provides an important nonclassical resource, which may be used in quantum communication and quantum optics.

We study particle production of coherently oscillating inflaton in semiclassical theory of gravity by representing inflaton in coherent and squeezed state formalisms. A comparative study of the inflaton in classical gravity with coherent state inflaton in semiclassical gravity is also presented.

In this paper, we have investigated the positive-parity states in the odd-mass transitional ${}^{123-135}$Xe isotopes within the framework of the interacting boson–fermion model. Two solvable extended transitional Hamiltonians which are based on SU(1,1) algebra are employed to provide an investigation of quantum phase transition (QPT) between the spherical and deformed gamma — unstable shapes along the chain of Xe isotopes. The low-states energy spectra and B(E2) values for these nuclei have been calculated and compared with the experimental data. The predicted excitation energies and B(E2) transition rates of the odd isotopes are found to agree well with the experimental data. We have also analyzed the critical behavior of even–odd Xe isotopes via Catastrophe Theory in combination with a coherent state formalism to generate energy surfaces and special isotopes which are the best candidates for the critical point are identified.

We derive a rigorous quantum formula called topological trajectory to describe orbital angular momentum (OAM) index based on linear momentum density of Laguerre–Gauss (L–G) light beam. By considering the correspondence between optics and quantum theory, we construct a coherent state from two L–G modes light beam. The light beams with fractional OAM are described by the coherent state. By making use of topological trajectory, we present the conditions that OAM index is fractional.

Quantum teleportation is one of the most important manifestations of nonlocal nature. The basic theory and experiment are explained and reviewed for a qubit system and a continuous-variable system.