Physics Letters A

A resonant transition amplitude, valid to arbitrary order, is derived through the use of a complex energy T-matrix. A feature of this amplitude is its generality and simplicity making it useful for widespread applications in resonance theory.

We begin by giving correct expressions for the short-time action following the work Makri-Miller. We use these estimates to derive an accurate expression modulo [Formula: see text] for the quantum propagator and we show that the quantum potential is negligible modulo [Formula: see text] for a point source, thus justifying an unfortunately largely ignored observation of Holland made twenty years ago. We finally prove that this implies that the quantum motion is classical for very short times.

The upper limit of momentum transfer by a proton to K-shell electrons is calculated in a restricted three-body classical model. The model shows that the infinite upper limit used in practice, is generally good except for low energy protons passing through an extremely rarefied gas.

Statistical physics and information theory is applied to the clinical chemistry measurements present in a patient database containing 2.5 million patients' data over a 20-year period. Despite the seemingly naive approach of aggregating all patients over all times (with respect to particular clinical chemistry measurements), both a diurnal signal in the decay of the time-delayed mutual information and the presence of two sub-populations with differing health are detected. This provides a proof in principle that the highly fragmented data in electronic health records has potential for being useful in defining disease and human phenotypes.

In this work, a method for storing and retrieving spatio-temporal patterns in large systems of coupled delay differential equations is presented. Spatio-temporal patterns are sets of sequences of binary variables of fixed period that are embedded in the network dynamics as stable limit cycles. As a consequence, an input signal converges to the limit cycle that best represents it. A given set of limit cycles is constructed using a generalization of the correlation learning rule in the definition of the couplings

We consider the delayed feedback control (DFC) scheme for one dimensional discrete time systems. To analyze the stability, we construct a map whose fixed points correspond to the periodic orbits of the system to be controlled. Then the stability of the DFC is equivalent to the stability of the corresponding equilibrium point of the constructed map.

The electronic contribution to the attenuation of sound waves is dependent on the product a = qℓ, q being the phonon wave number and ℓ the electron mean free path.1 For qℓ » 1, the attenuation parameter \(\frac{\alpha }{\nu }\) ν being the phonon frequency, is independent of qℓ. In general, the attenuation at arbitrary qℓ can be expressed in the form $$\frac{\alpha }{\nu } = \mathop {\lim }\limits_{q\ell \to \infty } \left( {\frac{\alpha }{\nu }} \right){\text{ }}P\left( {q\ell } \right)$$ (1) where P(qℓ) tends to unity for large qℓ.

Information is inevitably tied to a physical representation and therefore to restrictions and possibilities related to the laws of physics and the parts available in the universe. Quantum mechanical superpositions of information bearing states can be used, and the real utility of that needs to be understood. Quantum parallelism in computation is one possibility and will be assessed pessimistically. The energy dissipation requirements of computation, of measurement and of the communications link are discussed. The insights gained from the analysis of computation has caused a reappraisal of the perceived wisdom in the other two fields. A concluding section speculates about the nature of the laws of physics, which are algorithms for the handling of information, and must be executable in our real physical universe.

A newly derived generalized moments expansion (GMX), based on the “t-expansion” of Horn and Weinstein, is used to calculate the correlation energy of a model Hamiltonian representing N coupled one-dimensional harmonic oscillators. Comparisons are made with a related calculational scheme the canonical sequence method (CSM).

We introduce a new observable for reading out a which-way detector in a Young-type interferometer whose eigenstates either contain full which-way information or none at all. We calculate the which-way knowledge K that can be retrieved from this observable and find that K depends on the phase difference \delta that the interfering object accumulates on its way from either slit to the detector. In particular, it turns out that K(\delta) has an upper bound of 1, almost independent of the visibility V of the interference pattern generated by the interfering object on a screen, which is in marked contrast to the well-known inequality K^2 + V^2 <= 1 (cf. B.-G. Englert, Phys. Rev. Lett. 77, 2154 (1996)).

Dilute solution of He 3 in He 4 near absolute zero measured for viscosity, showing temperature effect

The effective charges extracted from measured stopping powers of heavy ions depend clearly on the stopping medium. Effective charges in gases differ systematically from the measured mean charge states after the medium.

We investigate the transmission of electrons through a quantum point contact by using a quasi-one-dimensional model with a local bound state below the band bottom. While the complete transmission in lower channels gives rise to plateaus of conductance at multiples of $2e^{2}/h$, the electrons in the lowest channel are scattered by the local bound state when it is singly occupied. This scattering produces a wide zero-transmittance (anti-resonance) for a singlet formed by tunneling and local electrons, and has no effect on triplets, leading to an exact $0.75(2e^{2}/h)$ shoulder prior to the first $2e^{2}/h$ plateau. Formation of a Kondo singlet from electrons in the Fermi sea screens the local moment and reduces the effects of anti-resonance, complementing the shoulder from 0.75 to 1 at low temperatures.

We provide a security analysis of the Y-00 protocol under heterodyne measurement and correlation attack. We show that the secrecy of the data encryption scheme is extremely sensitive to the running-key generation process. In many situations our simple attack succeeds in recovering the initial shared secret key. Our simulation results suggest that a truly secure implementation of the protocol should take into account the effective key generation method. (c) 2006 Elsevier B.V. All rights reserved.

The potential weakness of the Y-00 direct encryption protocol when the encryption box ENC in Y-00 is not chosen properly is demonstrated in a fast correlation attack by S. Donnet et al in Phys. Lett. A 35, 6 (2006) 406-410. In this paper, we show how this weakness can be eliminated with a proper design of ENC. In particular, we present a Y-00 configuration that is more secure than AES under known-plaintext attack. It is also shown that under any ciphertext-only attack, full information-theoretic security on the Y-00 seed key is obtained for any ENC when proper deliberate signal randomization is employed.

It is claimed by T. Nishioka et al. in [T. Nishioka, T. Hasegawa, H. Ishiziuka, K. Imafuku, H. Imai, Phys. Lett. A 327 (2004) 28-321 that the security of Y-00 is equivalent to that of a classical stream cipher. In this Letter it is shown that the claim is false in either the use of Y-00 for direct encryption or key generation, in all the parameter ranges it is supposed to operate including those of the experiments reported thus far. The security of Y-00 type protocols is clarified. (c) 2005 Elsevier B.V. All rights reserved.

New quantum cryptography, often called Y-00 protocol, has much higher performance than the conventional quantum cryptographies. It seems that the conventional quantum cryptographic attacks are inefficient at Y-00 protocol as its security is based on the different grounds from that of the conventional ones. We have, then, tried to cryptoanalyze Y-00 protocol in the view of cryptographic communication system. As a result, it turns out that the security of Y-00 protocol is equivalent to that of classical stream cipher.

By using the density functional theory method, we systematically study the influences of the doping of an Al atom on the electronic structures of the Mg(0001) surface and dissociation behaviors of H2 molecules. We find that for the Al-doped surfaces, the surface relaxation around the doping layer changes from expansion of a clean Mg(0001) surface to contraction, due to the redistribution of electrons. After doping, the work function is enlarged, and the electronic states around the Fermi energy have a major distribution around the doping layer. For the dissociation of H2 molecules, we find that the energy barrier is enlarged for the doped surfaces. Especially, when the Al atom is doped at the first layer, the energy barrier is enlarged by 0.30 eV. For different doping lengths, however, the dissociation energy barrier decreases slowly to the value on a clean Mg(0001) surface when the doping layer is far away from the top surface. Our results well describe the electronic changes after Al-doping for the Mg(0001) surface, and reveal some possible mechanisms for improving the resistance to corrosion of the Mg(0001) surface by doping of Al atoms.

In an attempt to find generic features on the fractal growth of Au films deposited on Ru(001), a simple simulation model based on irreversible diffusion-limited aggregation (DLA) is discussed. Highly irregular two-dimensional dentritic islands of Au particles that gradually grow on a larger host lattice of Ru particles and have fractal dimension d_{f}~ 1.70 each, are generated via a multiple had-hoc version of the DLA algorithm for single aggregates. Annealing effects on the islands morphology are reproduced assuming different sticking probabilities at nearest-neighbour lattice sites of Au films on Ru(001). Using simulation data, islands growth are described in analogy to diffusion-limited, precipitate growth with soft impingement of precipities. This leads to analyse thin film island growth kinetics in such fractal systems and to predict a main peak in scattering intensity patterns due to interisland interference. ---------------- Copies upon request to: canessae@itsictp.bitnet Comment: CM-ICTP/92/123

Iridium adsorption on γ-Al2O3 (001) surface has been studied using the ab initio calculation method and the electronic structures of the bare and the Ir adsorbed γ-Al2O3 (001) surfaces have been analyzed. By modeling different adsorption sites, one can conclude that the energetically most favorable sites for the Ir are the top sites of the O atoms at the γ-Al2O3 (001) surface terminated with octahedral Al. Charge redistribution around the Ir atom adsorbed on the surface improves the activity of the Ir atom as a catalyst.

We have measured the binding energy shift of the Au-4f core levels at the (001) surface of equi-atomic CuAuI. We show that this result enables us to make a definitive determination of the termination at the surface.

All the hermitian representations of the ``symmetric" $q$-oscillator are obtained by means of expansions. The same technique is applied to characterize in a systematic way the $k$-order boson realizations of the $q$-oscillator and $su(1,1)_q$. The special role played by the quadratic realizations of $su(1,1)_q$ in terms of boson and $q$-boson operators is analysed and clarified. Comment: 13 pages, AMS-TEX file, UVA/93-92

We decouple the Dirac's radial equations in $D+1$ dimensions with Coulomb-type scalar and vector potentials through appropriate transformations. We study each of these uncoupled second-order equations in an algebraic way by using an $su(1,1)$ algebra realization. Based on the theory of irreducible representations, we find the energy spectrum and the radial eigenfunctions. We construct the Perelomov coherent states for the Sturmian basis, which is the basis for the unitary irreducible representation of the $su(1,1)$ Lie algebra. The physical radial coherent states for our problem are obtained by applying the inverse original transformations to the Sturmian coherent states.

A 1.5 um synchronous heralded single photon source (HSPS) is experimentally demonstrated based on dispersion shifted fiber and commercial fiber components in the paper. Experimental results show that both the preparation efficiency and the conditional second order correlation function g2(0) increase with the pump light level. Between the two important parameters, tradeoff should be taken in order to obtain a high quality fiber-based synchronous HSPS. A synchronous HSPS with a prepare efficiency of >60% and g2(0)<0.06 is achieved, the multi-photon probability of which is reduced by a factor of more than 16 compared with the Poissonian light sources. The experimental results show a great potential of the fiber-based synchronous HSPS for quantum information applications. Comment: 5 pages, 3 figures

We present an easy analytical method for designing dispersion-managed fiber systems with map strength of 1.65, where the transmission lines have minimal pulse–pulse interactions.

Light mixing techniques were used to scatter at small forward angles with a hybrid CO2-laser from a thermal plasma. The ion temperature and the enhancement of ion-acoustic resonances by ion-ion collisions were obtained from the scattered spectrum recorded in one shot.

Theoretical results are given for the electrical conductivity of a hot dense plasma. The gradient formulation of density functional theory is applied to calculate the ionization states and electron-ion potentials. Elastic scattering cross sections are obtained by partial wave calculations. These are then combined with ionic static structure factors to compute electrical resistivity according to the extended Ziman formula. Calculation results are compared with qualitatively novel experimental data.

The similarity of distinctive skeletal structures (namely, cartwheels and tubules) in the range 10−5–1023 cm is found. The former analysis of dust deposits in tokamak (10−6–10−3 cm) and of electric discharges in tokamaks, Z-pinches, plasma focus and vacuum spark (10−2–10 cm) is extended here to hail particles (1–10 cm), tornado (103–105 cm), and various objects in space (1011–1023 cm). The similarity and the observed trend toward self-similarity within above skeletal structures suggest all of them, similarly to skeletons in the particles of dust and hail, to be basically a fractal condensed matter which, similarly to submicron dust skeletons, is assembled from nanotubular blocks.

The authors of the paper indicated in the title derived an erroneous effective free energy of superconducting slabs (films) and this error led them to entirely wrong conclusions. Here we shall make clear the genesis of this mistake. Comment: 4 pages, Miktex; submitted to Phys. Lett. A

The highly energetic and high fluence argon ions emitted in a dense plasma focus device have been used for the first time to get fullerene films by ablating the graphite target such that the ablated material is deposited on a Si(111) substrate. These films have been studied using XRD, high resolution transmission electron microscopy (HRTEM), Raman spectroscopy, FTIR spectroscopy and SEM microscopy. The XRD, Raman and FTIR spectra show peaks corresponding to fullerenes, mainly C60 and C70. Moreover, prominent peaks of C60 have been observed in XRD spectra. The TEM micrograph shows crystalline fullerene structures and the selected area diffraction (SAD) pattern shows single crystalline spot patterns exhibiting the (110) and (006) planes of the hcp C60 clusters. The SEM micrographs also show spherical clusters of fullerenes.

Perturbed angular correlation measurements were performed after 111In implantation into CuO and Cu2O powder samples and 1 μm thick Cu2O surface layers. The quadrupole hyperfine interaction of 111Cd was studied in isochronal annealing cycles at 370–1170 K covering the CuO→Cu2O phase transition. The electric field gradients obtained for 111Cd on substitutional Cu lattice sites were associated with the repective oxygen coordinations. Annealing of Cu2O surface layers on copper foils resulted in a texture with the efg pointing preferentially out of the surface plane.

Using a surface ionization ion microscope the desorption kinetics and the directional dependence of the diffusion of potassium were measured on an oxygen covered W(112) surface at extremely low K-coverages. The mean adsorption lifetime τ can be expressed as τ = 4.8×10−14 s×exp(2.24 eV/kT); compared to the clean surface the activation energy of ionic desorption is reduced by 0.3 eV. The oxygen coverage does not change the anisotropy of diffusion observed on the clean surface fundamentally, but slows down the diffusion process. The diffusion constants along the [1̄1̄1] direction (direction of the “channels” on W(112)) and at an angle of 60° relative to it are given by D∥,ox = 0.9 cm2 s−1 × exp(−0.60 eV/kT) and D60°,ox = 0.2 cm2 s−1 × exp(−0.72 eV/kT), respectively.

We report on the IR spectroscopic studies in both reflection (50-900 cm^{-1}) and transmission (900-3000 cm^{-1}) mode of the vibration spectrum of the cuprous oxide. A detailed analysis based on a comparison of the temperature dependences of the absorption band at 1125 cm^{-1} and of IR and Raman active fundamental vibrations results in assignment of the former to a biphonon. Comment: 5 pages, 5 figures (to appear in Phys.Lett. A)

A new mathematical instability technique is presented and applied to determine the stability properties of a physically important class of standing waves in nonlinear planar optical waveguides. The method is illustrated by a case where soliton perturbation techniques or variational methods are inapplicable.

HCN laser harmonic frequency mixing with two different far IR laser lines with microwave intermediate frequencies, discussing mixing SNR magnitudes

In this reply Letter, N.A. Kudryashov's comments on the approach for solving the Fisher equation by using Exp-function method is made comprehensible for the third side.

Spin-lattice relaxation times T1 for deuterons and 11B nuclei were measured in solid NaBD4. The quadrupole coupling constant e2qQ/h of deuterons was found to be 107 kHz. The activation energies for the motion of BD4 ion were also determined.

Fermiology of various 122 systems are studied through first principles simulation. Electron doping causes expansion of electron and shrinkage of hole Fermi pockets. Isovalent Ru substitution (upto 35%) makes no visible modification in the electron and hole like FSs providing no clue regarding the nature of charge carrier doping. However, in case of 32% P doping there are considerable changes in the hole Fermi surfaces (FSs). From our calculations, it is very clear that two dimensionality of FSs may favour electron pair scattering between quasi-nested FSs which has important bearings in various orders (magnetic, orbital, superconducting) present in Fe-based superconductors.

The equilibrium properties of the mixed state are investigated by means of the differential susceptibility X'H in the reversible domain up to 4 T for the Hg-1223 superconducting phase. The penetration depth λab(0)≈1100 Å is deduced and the role of the thermal fluctuations on vortices is considered within the approach of Bulaevskii et al. This allows an estimation of a crossover field Hcr related to the Josephson coupling and hence to the anisotropy for which we give a lower estimated value of 16. The low anisotropy level may point to a less 2D character of this Hg based superconductor as compared to Tl and Bi based cuprates and this can explain why the observation of clear specific heat anomalies at the superconducting transition is possible for similar samples containing the Hg-1223 and the Hg-1212 phases. The height of the specific heat anomaly is comparable to that of the YBCO system and from Cp(H) measurements we can deduce an average H'c2 slope ≈2 T/K for 1223 and 4 T/K for 1212. Finally, from the ac susceptibility we show evidence for diamagnetic fluctuations in the normal state up to 200 K.

The resonance absorption of the 129 keV γ rays from the second excited state in 195Pt has been investigated. The spectrum exhibits a 0.16% effect and a linewidth of 4.4 ± 0.4 mm/s. The possibility of using this resonance for solid studies is suggested.

Sidebands intensities and quantum beats were measured at different vibration amplitudes of sources containing 129mTe, using the Mössbauer effect of 27.8 keV gamma rays emitted in its decay. The results can be understood in terms of a broad distribution of the amplitudes of the vibrating nuclei combined with a phase distribution with a standard deviation of 0.42 radians.

The combined influences of boundary effects at large scales and nonzero nearest neighbor separations at small scales are used to compute intrinsic limits on the minimum size of a data set required for calculation of scaling exponents. A lower bound on the number of points required for a reliable estimation of the correlation exponent is given in terms of the dimension of the object and the desired accuracy. A method of estimating the correlation integral computed from a finite sample of a white noise signal is given.

We present here a method of finding time independent integrals of motion for a given three-dimensional vector field X. This method is based on the Frobenius integrability theorem. The integral is obtained as a solution of one ODE of the first order. As examples we study the May-Leonard, Lotka-Volterra and Lorenz equations. Some new integrable cases are found.

By means of non-resonant microwave absorption in low magnetic fields it is found that the superconducting Tc significantly decreases in 60% 13C isotope substituted K3C60 and Rb3C60. The exponent α of the isotope effect, Tcrmc1/mα, is estimated roughly to be α=1.2–2.25, much higher than predicted by the BCS theory. The intrinsic disorder is observed both in the wide-mass spectrum and the dramatically changed IR spectrum reflecting the inhomogeneous distribution of 13C isotopes in 13C60−n12C60 molecules. The large positive α supports the intramolecular vibronic pairing, and the decrease of the electron-vibron coupling λ due to the disturbed symmetry of Hg modes in mixed 13C60−n12Cn molecules is proposed to contribute to the enhanced α, in addition to the conventional isotope frequency shift.

The structure and magnetic properties of cobalt doped Sin (n=2–14) clusters have been systematically studied using density functional theory (DFT). For each cluster size, extensive search of the lowest-energy structure has been conducted by considering a number of structural isomers. The equilibrium site of the Co atom in the ground-state structures of SinCo clusters gradually moves from convex, surface, to interior sites as the number of Si atom increases from 2 to 14. Starting from Si10Co, Co atom is fully encapsulated by the Si outer cages. The magnetic moment of Co atom in SinCo clusters is completely quenched at n=7, due to charge transfer and strong hybridization between 4s and 3d states of Co and 3s and 3p states of Si.

Inelastic incoherent neutron scattering spectra of recovered high pressure H2O and D2O ice VIII were measured in the range 2–140 meV at 25 K using the TFXA spectrometer at ISIS. The excellent resoltion of this instrumentyields detailed information on the dynamics of ice VIII, in particular about the translational modes below 35 meV and about the librational modes from 54 to 115 meV for H2O and from 40 to 90 meV for D2O. In the translational region, the first peak in the acoustic mode region is shifted by 7.6 meV towards higher energies as compared to ice Ih. It is also important to note that the strong feature that appears in the inelastic spectra of all other measured ice structures is completely missing from the present spectra for both isotopes. In the librational mode region, the spectrum shows that the low energy cut-off of the librational band shifts 12 meV towards low energy transfers as compared with ice Ih for both isotopes. In addition, two sharp peaks are seen at energy transfers of 55 and 68 meV for H2O (41.5 and 49.9 meV for D2O) which are not seen in other forms of ice.

A family of two spin states with the following properties is presented. These states are “local” in the sense that they do not violate any Bell—CHSH inequality. However, after each spin interacts with two independent local environments, the resulting states of the two spin systems violate a Bell inequality. It is argued that: (1) The problem of classifying the nonlocal states of two spin systems is still open. In particular, for mixed states the violation of Bell's inequality and the concept of nonlocality differ, (2) The fact that some dissipative environments can increase quantum correlations might be useful for quantum computation. (3) Careless application of generalized quantum measurements can violate Bell's inequality by more than 2√2, even for mixtures of product states.

We prove that any non-product state of two-particle systems violates a Bell inequality.

The electrochemical characteristics of the ball-milled Ti–30V–15Mn–15Cr+20 wt% La(NiMnCoAl)5 alloy electrodes were investigated. After 30 min ball-milling, the composite sample exhibits a higher discharge capacity and a longer cycle life. It could be attributed to the uniform disperse of the La(NiMnCoAl)5 alloy particles on the surface of the composite sample, which not only acts as both an electro-catalyst and a micro-current collector, but also prevents the V dissolution into the alkaline electrolyte during the charge–discharge cycles.

The density functional calculation with the generalized gradient approximation is applied to study the structural, electronic and vibrational properties of InnSbn clusters up to n=16. A family of fullerene-like InnSbn clusters with n=9–16 is found. Meanwhile In5Sb5 and In12Sb12 show obvious magic-number behavior. We also discuss the size dependence of binding energies, gap between highest-occupied and lowest-unoccupied molecular orbitals, second-difference of total energies, electron affinities, ionization potential, Mulliken charges, and the IR spectra of InnSbn clusters.