Even and odd coherent states are “shadowed-like” states

Shadowed states were introduced recently in the literature. It was shown that these states always exhibit nonclassical effects [R. Srinivasan and C.T. Lee, Phys. Lett. A 218 (1996) 151]. Here we show that the well known even and odd coherent states are shadowed-like states, whose differences and similarities are discussed.     

Kaluza-Klein states versus winding states: can both be above the string scale?

Closed strings in extra compactified dimensions give rise to both Kaluza-Klein states and winding states. Since the masses of these states play a reciprocal role, it is often believed that either the lightest Kaluza-Klein states or the lightest winding states must be at or below the string scale. In this Letter, we demonstrate the contrary, showing that there exist toroidal compactifications for which all Kaluza-Klein states as well as all winding states are heavier than the string scale. Within the context of low-scale string theories, this implies that it may be possible to cross the string scale without detecting any states associated with spacetime compactification.     

η-nucleus bound states in nuclei

The binding energies η and widths Γη of η-mesic nuclei are calculated.We parameterize the η self-energy in the nuclear medium as a function of energy and density.We find that the single-particle energies are sensitive to the scattering length,and increase monotonically with the nucleus.The key point for the study of η-nucleus bound states is the η-nuclear optical potential.We study the s-wave interactions of η mesons in a nuclear medium and obtain the optical potential Uη≈ -72 MeV.Comparing our results with the previous results,we find that the ηN scattering length aηN is indeed important to the calculations.With increasing nuclear density the effective mass of the η meson decreases.     

Nuclear bound states of ω mesons

Models based on chiral SU(3)_l ⊗ SU(3)_r symmetry and vector meson dominance suggest an attractive potential for the ω meson in a nuclear medium. We discuss the feasibility of producing nuclear bound states of ω mesons using (d, ³He) and pion induced reactions on selected nuclear targets.     

Bound states and resonance states of the plasma-embedded tdμ and ddμ molecular ions

We have investigated the bound states and resonance states of plasma-embedded tdμ and ddμ molecular ions using accurate correlated basis functions. The plasma effect has been taken care of by considering the Debye shielding approach of plasma modeling which admits a variety of plasma conditions. The density of resonance states are calculated using the stabilization method. The ground and excited states energies, and the S-wave resonance energies of tdμ and ddμ molecular ions immersed in plasmas are reported for various shielding parameters, along with the 1S and 2S threshold energies of the tμ and dμ atoms.     

High-order squeezing of pure superposition states

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Amplitude-N-power squeezing of pure superposition states

The N-order squeezing of the pure superposition states |a,β>_(mn)=a|m> β|n> is studied. We find that there is only N=n—m order squeezing for odd (n—m) except for (n—m)=1(m≥1) , but there are N=n—m order and N=(n—m)/2 order squeezings for even (n—m).     

Strange quarkonium states at BESⅢ

We present physics opportunities and topics with the s states(strangeonia)that can be studied with the BES detector operating at the BEPC collider.Though the φ and η/ states have long been established experimentally,only a handful of strangeonia are well known,in contrast to the rich ccharmoium system.An overview of the s states and their experimental status is presented in this paper.The BES experiment has collected the world’s largest samples of J/ψ,ψ(2S),ψ(3770),and direct e+e-annihilations at energies below the J/ψand above 3.8 Ge V,and will continue to accumulate high quality,large integrated luminosity in theτ-charm energy region.These data,combined with the excellent performance of the BESⅢ detector,will offer unprecedented opportunities to explore the s system.In this paper we describe the experimental techniques to explore strangeonia with the BESⅢ detector.     

η-nucleus bound states in nuclei

The binding energies εη and widths Гη of wmesic nuclei are calculated. We parameterize the η self-energy in the nuclear medium as a function of energy and density. We find that the single-particle energies are sensitive to the scattering length, and increase monotonically with the nucleus. The key point for the study of η-nucleus bound states is the η-nuclear optical potential. We study the s-wave interactions of η mesons in a nuclear medium and obtain the optical potential Uη ≈ -72 MeV. Comparing our results with the previous results, we find that the ηN scattering length aηN is indeed important to the calculations. With increasing nuclear density the effective mass of the η meson decreases.     

Exotic states with QQ■ configuration

In the framework of a non-relativistic quark model, we have calculated the masses of the QQ■(Q = c, b, s and ■=■,■,■) tetraquark states. Using the linear and quadratic confinement potentials inside a Cornell-type potential along with all possible spin and color configurations, the Schr?dinger equation masses of these tetraquark states have been calculated.Based on our numerical analysis, linear confinement and quadratic confinement produce acceptable results. Models that use linear confinement e...     

Remarks on 2–q-bit states

We distinguish six classes of families of locally equivalent states in a straightforward scheme for classifying all 2–q-bit states; four of the classes consist of two subclasses each. The simple criteria that we stated recently for checking a given state’s positivity and separability are justified, and we discuss some important properties of Lewenstein–Sanpera decompositions. An upper bound is conjectured for the sum of the degree of separability of a 2–q-bit state and its concurrence. Received: 17 July 2000 / Published online: 6 December 2000     

Exploring ground states and excited states of spin-1 Bose–Einstein condensates by continuation methods

A pseudo-arclength continuation method (PACM) is employed to compute the ground state and excited state solutions of spin-1 Bose–Einstein condensates (BEC). The BEC is governed by the time-independent coupled Gross–Pitaevskii equations (GPE) under the conservations of the mass and magnetization. The coupling constants that characterize the spin-independent and spin-exchange interactions are chosen as the continuation parameters. The continuation curve starts from a ground state or an excited state with very small coupling parameters. The proposed numerical schemes allow us to investigate the effect of the coupling constants and study the bifurcation diagrams of the time-independent coupled GPE. Numerical results on the wave functions and their corresponding energies of spin-1 BEC with repulsive/attractive and ferromagnetic/antiferromagnetic interactions are presented. Furthermore, we reveal that the component separation and population transfer between the different hyperfine states can only occur in excited states due to the spin-exchange interactions.     

Preparing quantum vortex states with odd Schrdinger cat states through a coupled waveguide system

A scheme is proposed for preparing a quantum vortex state with a coupled waveguide, in which a single-mode odd cat state with weak intensity and a single-mode coherent state are inserted in the input ports, respectively. The analytical wavefunction of the resulting state in the quadrature space is derived, and the vortex structure of the output state is analyzed. It is found that the obtained states, which may carry a vortex with topological charge index one, are entangled and nonclassical, depending only on the scaled propagation time and the weak intensity of the input odd cat state instead of the displacement parameter of the input coherent state. The phase distribution, however, in the quadrature space, depends on the displacement parameter of the input coherent state     

A secure identification system using coherent states

A quantum identification system based on the transformation of polarization of a mesoscopic coherent state is proposed. Physically, an initial polarization state which carries the identity information is transformed into an arbitrary elliptical polarization state. To verify the identity of a communicator, a reverse procedure is performed by the receiver. For simply describing the transformation procedure, the analytical methods of Poincar\'{e} sphere and quaternion are adopted. Since quantum noise provides such a measurement uncertainty for the eavesdropping that the identity information cannot be retrieved from the elliptical polarization state, the proposed scheme is secure.     

Separability criteria for multipartite quantum mixed states

The separability of mixed states in multipartite quantum systems is investigated. If a quantum state in a multipartite system with an arbitrary dimension is separable, some quantity in relation to Hermitian matrix is positive.     

Superfluid states in α–T_3 lattice

The superfluid states of attractive Hubbard model in α–T_3 lattice are investigated. It is found that one usual needs three non-zero superfluid order parameters to describe the superfluid states due to three sublattices. When two hopping amplitudes are equal, the system has particle–hole symmetry. The flat band plays an important role in superfluid pairing near half filling. For example, when the filling factor falls into the flat band, the large density of states in the flat band favors superfluid pairing and the superfluid order parameters reach relatively large values. When the filling factor is in the gap between the flat band and upper band, the superfluid order parameters take small values due to the vanishing of density of states. The superfluid order parameters show nonmonotonic behaviors with the increase of filling factor. At last, we also investigate the edge states with open boundary conditions. It is shown that there exist some interesting edge states in the middle of quasi-particle bands.     

The production of narrow Σ-hypernuclear states

It has been suggested that some of the observed narrow Σ hypernuclear states may be “bound states in the continuum” of the Σ interacting with the host nucleus formed when that interaction is strongly absorptive. It is shown that the S matrix for such a process vanishes at the complex energy of such a bound state. Some general properties of the S matrix in the presence of absorption are derived.