The positron-helium bound state

A variational calculation with a trial wave function including up to 17 parameters has been used to investigate the existence of a positron-helium bound state. The resulting binding energy was found to be greater than the helium binding energy, and thus it is believed that the positron does not get bound to a helium atom. The calculations provide also values of ground state helium energy and the corresponding wave functions.     

Superconducting virtual bound state alloys

Static and dynamic properties of superconducting alloys containing resonant impurity scattering centers are considered. The formation of bound states within the energy gap is described and connected with locald-level correlations induced by superconductivity. The effect of the bound states on the exactly solubled-spin dynamics is investigated by evaluating the impurity atom's magnetic excitation spectrum. Finite impurity concentrations are treated within a self-consistent approximation scheme. For increasing impurity content the bound states merge to impurity bands which tend to suppress superconductivity. The relevance of the simple extra orbital model is discussed in connection with the interpretation of pressure-induced variations on the properties of superconductors alloyed with ambivalent rare earth ions.     

Driven systems with one bound state

Schwinger's quantum action principle is used to calculate transition amplitudes in systems with a single bound state that are driven by a time-dependent force. Applications to the study of multiphoton processes in the negative hydrogen ion are hinted at.     

Electron-positron scaling in bound state models

We investigate scaling assuming a generalized vector meson dominance picture. The vector mesons are described as relativistic quark-antiquark bound states by a Bethe-Salpeter equation which yields the mass spectrum and the coupling to e⁺e^? pairs. We discuss the spin structure and find that scaling can occur only for a γ_μ type amplitude. We solve the BS equation using a generalized WKB approximation and find scaling, independent of the detailed shape of the interaction. This means that scaling in e⁺e^? annihilation does not select a particular “confinement potential”. The scaling constant depends on the current renormalization constant and on the details of the relativistic spin structure.     

Relativistic two-body bound state in motion

For an approximately relativistic Hamiltonian properties of a two-body bound state are investigated as a function of the total momentum. These are the relativistic energy-momentum relation for the bound-state energy eigenvalue, integral and local deformation properties of the bound-state wave function, and the weakly singular short-range behaviour.     

The bound state of two-electrons in crystals

The bound state of two-electrons and the existence of a bipolaron are studied using the expression of the effective potential of interactions in crystals by considering in addition to the electron-lattice, i.e. electron-phonon interaction, also the electron-electron, i.e. electron-plasma interaction. It is shown that the electron-electron interaction strengthens the bound state, making the potential gap deeper and wider, and leads to the appearance of a supplementary narrow gap, the so-called plasma gap. The conditions for the existence of the bound state of two electrons, i.e. a bipolaron, are established and the case of germanium is analyzed in detail. The result of calculating the energy minimum value and the effective potential contains — as limit cases in the single-electron approximation — the well-known results given in literature.     

Exponential decay of bound state wave functions

The spatial decay properties of the wave functions of multiparticle systems are investigated. The particles interact through pair potentials in the classR+L . The bound states lie below the bottom of the continuous spectrum of the system. Exponential decay, in anL ² sense, is proven for these wave functions. The result is the best possible one which will cover every potential in this class.Based on a thesis submitted to Princeton University in partial fulfillment of the degree of Doctor of Philosophy.     

Normal state of highly polarized Fermi gases: The bound state

We consider a highly polarized Fermi gas with a single ↓ atom within a Fermi sea of ↑ atoms. We extend a preceding many-body analysis to the case where a bound state is formed between the ↓ atom and an ↑ atom.     

Off-shell effects in the three-nucleon bound state

Phase-shift-equivalent separable potentials are used to study the sensitivity of the triton binding energy E_T to the off-shell behavior of the two-nucleon T matrix. It is found that the deuteron wave function significantly constrains the theoretical uncertainty in E_T and that the properties of the off-shell T matrix at intermediate energies are only weakly reflected in E_T.     

Experimental bound entanglement in a four-photon state

Bound entanglement is central to many exciting theoretical results in quantum information processing, but has thus far not been experimentally realized. In this work, we consider a one-parameter family of four-qubit Smolin states. We experimentally produce these states in the polarization of four optical photons produced from parametric down-conversion. Within a range of the parameter, we show that our states are entangled and undistillable, and thus bound entangled. Using these bound-entangled states we demonstrate entanglement unlocking.     

Effective field theory for bound state reflection

Elastic quantum bound-state reflection from a hard-wall boundary provides direct information regarding the structure and compressibility of quantum bound states. We discuss elastic quantum bound-state reflection and derive a general theory for elastic reflection of shallow dimers from hard-wall surfaces using effective field theory. We show that there is a small expansion parameter for analytic calculations of the reflection scattering length. We present a calculation up to second order in the effective Hamiltonian in one, two, and three dimensions. We also provide numerical lattice results for all three cases as a comparison with our effective field theory results. Finally, we provide an analysis of the compressibility of the alpha particle confined to a cubic lattice with vanishing Dirichlet boundaries.     

The optical properties of virtual bound state alloys

Optical data on dilute CuNi, AuNi and AgPd alloys are examined in terms of the Anderson model. The results for AuNi and AgPd appear to be consistent with the model while those for CuNi are not. A consistent interpretation of the data is obtained when the effects of the s-d hybridization of the copper conduction states on the Anderson mixing matrix element, V_kd, are considered. The results suggest a rapid increase in V_kd as the energy ?_k approaches the copper d bands.     

He-LiH体系束缚态能级的理论计算

在CCSD(T) 势能面的基础上,采用严格的量子力学方法计算得到了He-LiH体系束缚态振转能级和波函数,结果表明该体系存在10个振转束缚态.从波函数的分布图中可以知道,与J=0的第一个能级对应的本征态是靠近Li端较深势阱的一个束缚态;第二个能级为伸展激发振动能级;基本上存在于深势阱内,但H端的浅势阱通过隧道效应,对该能级的几率分布产生了影响.     

Effect of noise on a quantum bound state

The evolution of a quantum wave function on a lattice with time-dependent random disorder is studied. It is found that the bound state wave function of a quantum system exhibits intrinsic instability with respect to noisy disorder in the statistical sense. Under the general scheme of time coarse graining, we show nonperturbatively that the stationary attractive potential is completely washed out at large time scales by the existence of the noisy disorder to any order of density correlations.     

A iterative method of bound state energy calculation

An iterative method of solution of the Lippmann-Schwinger-type equation is proposed. This method is applicable to the bound state energy calculations of strongly coupled particles and can also be applied to the Faddeev equations. The convergence of this method is tested on the Lippmann-Schwinger equation.     

广义振子势的精确束缚态解

本文求解了广义振子势在r,θ,φ方向上的Schrǒdinger方程,得到了它的能级和相应的归一化角向、径向波函数.利用广义拉盖尔多项式的积分公式得到了广义振子势的径向矩阵元的通向表达式.     

Ground state energy of a bound piezoelectric polaron

The ground state energy of a piezoelectric polaron bound in a Coulomb potential is calculated analytically in the weak coupling limit.