Information Between Quantum Systems via POVMs

The concepts of conditional entropy and information between subsystems of a composite quantum system are generalized to include arbitrary indirect measurements (POVMs). Some properties of those quantities differ from those of their classical counterparts; certain equalities and inequalities of classical information theory may be violated. PACS: 03.67.-a.     

Magnetization of Gd cluster: Anomalous thermal behavior

Theoretical studies of the temperature (T) dependence of magnetization of Gd₁₃ clusters have been carried out within a classical Heisenberg model using Monte-Carlo simulations. It is shown that for a broad range of values of , defined as the ratio between competing ferro and anti-ferro magnetic couplings, the cluster magnetization increases with T in the low T region, as seen in experiment. The clusters are also shown to exhibit a wide distribution of moments at a given T, which broadens significantly with increasing T. It is suggested that this may affect the observed magnetic behavior of magnetic clusters in Stern-Gerlach experiments. Received 29 May 1999 and Received in final form 5 September 1999     

On Quantum Phase Transition. I. Spinless Electrons Strongly Correlated with Ions

We study a large class F of models of the quantum statistical mechanics dealing with two types of particles. First the spinless electrons are quantum particles obeying to the Fermi statistics, they can hop. Secondly the ions which cannot move, are classical particles. The Falicov–Kimball (FK) model⁽¹⁾ is a well known model belonging to F, for which the existence of an antiferomagnetic phase transition was proven in the seminal paper of Kennedy and Lieb.⁽²⁾ This result was extended by Lebowitz and Macris.⁽³⁾ A new approach to this problem based on quantum selection of the ground states was proposed in ref. 4. In this paper we extend this approach to show that, under the strong insulating condition, any hamiltonian of the class F admits, at every temperature, an effective hamiltonian, which governs the behaviour of the ions interacting through forces mediated by the electrons. The effective hamiltonians are long range many body Ising hamiltonians, which can be computed by a cluster expansion expressed in term of the quantum fluctuations. Our main result is that we can apply the powerfull results of the classical statistical mechanics to our quantum models. In particular we can use the classical Pirogov–Sinai theory to establish a hierarchy of phase diagrams, we can also study of the behaviour of the quantum inter- faces,⁽²⁹⁾ and so on...     

Hyperspectral Imaging Applications in Agriculture and Agro-Food Product Quality and Safety Control: A Review

Abstract

In this review, various applications of near-infrared hyperspectral imaging (NIR-HSI) in agriculture and in the quality control of agro-food products are presented. NIR-HSI is an emerging technique that combines classical NIR spectroscopy and imaging techniques in order to simultaneously obtain spectral and spatial information from a field or a sample. The technique is nondestructive, nonpolluting, fast, and relatively inexpensive per analysis. Currently, its applications in agriculture include vegetation mapping, crop disease, stress and yield detection, component identification in plants, and detection of impurities. There is growing interest in HSI for safety and quality assessments of agro-food products. The applications have been classified from the level of satellite images to the macroscopic or molecular level.     

Low-energy antimony implantation in silicon

Abstract

Antimony is known to be a donor in silicon, Low-energy implantations of Sb in Si produce very shallow profiles which have many device applications. Gibbons et al. ¹ calulated the projected ranges of Sb ion-implanted in Si, using the LSS (Lindhard, Scharff, and Schiott) method. Oetzmann et al. ² measured projected ranges and range straggling for several heavy ions in Si, Al, and Ge, using high-resolution backscattering; in the energy region of interest to us, e = 10^?2 to 10^?1, their results were about 30% higher than those reported by Gibbons et al. In the study reported here, we implanted 5 × 10¹⁴ Sb/cm² in Si at 5–60 keV, measured the resulting depth distribution by secondary ion mass spectrometry, and checked the measurements by backscattering. Our results showed the experimental projected ranges to be about halfway between those reported in the earlier studies. The discrepancies between theoretical calculations and experimental results are due not to the electronic stopping cross section, which is negligible in the range of interest here, but to the nuclear stopping power. Using a modified nuclear scattering potential given by Wilson et al.,³ we calculated the projected range distribution according to the method described by Winterbon.⁴ Our results are in very good agreement with the experimental measurements.     

Electrocaloric response in a relaxor ferroelectric polymer at temperatures far below the dielectric maximum

ABSTRACT

Relaxor ferroelectric polymer poly(vinylidene fluoride–trifluoroethylene–chlorofluoroethylene) (P(VDF-TrFE-CFE)) and its blends have been shown to exhibit a giant electrocaloric effect (ECE) over a broad temperature range, e.g. from 0 to 50 °C. Here, a special calorimeter was designed to directly characterize the heat absorbed Q_ECE due to ECE cooling of the blend of P(VDF-TrFE-CFE) with P(VDF-TrFE) 65/35 mol% copolymer down to ?15 °C, which covers the temperature range for many refrigeration applications. From Q_ECE, the isothermal entropy change ΔS and adiabatic temperature change ΔT are deduced. The data reveal that at ?15 °C the relaxor terpolymer/copolymer blend generates ΔS = 23.0J kg^?1 K^?1 and ΔT = 5.1K under 100 MV/m, which are still more than 65% of the ECE at room temperature. This temperature is far below the dielectric peak temperature of the relaxor blend and the results reveal the promise of the relaxor polymers for a broad range of EC cooling applications.     

One-and two-front states of equilibrium in a thin superconducting film

Two-phase states of equilibrium of a thin superconducting film carrying a current under conditions of convective heat exchange at the free surface of the film are studied. It is shown that for a classical superconductor the two-phase state of the film remains a single-front state over a wide range of parameters of the system. For high-T _c superconductors there exists a maximum value of the Steckl number above which weakly nonequilibrium stationary states can only be multifront states. The solutions of the boundary-value problem modeling a two-front state of equilibrium are investigated, and the conditions under which they obtain are examined. Zh. Tekh. Fiz. 68, 84–87 (March 1998)     

ESR studies on the pressure and temperature dependence of electron self-exchange kinetics between tetrathiafulvalene (TTF) and its radical cation in ionic liquids and organic solvents

The question whether chemical reactions and diffusion processes in ionic liquids are comparable with those taking place in classical organic liquids is a current issue in the literature. Pressure- and temperature-dependent investigations on simple electron self-exchange reactions between the two partners of a redox couple are good tools to get a better understanding of how the solvent influences such reactions. The electron self-exchange reaction between tetrathiafulvalene (TTF) and its radical cation has been investigated in two ionic liquids and two organic solvents using electron spin resonance (ESR) line broadening experiments at variable temperature and pressure. Rate constants are reported for the ionic liquids 1-ethyl-3methylimidazolium bis(trifluoromethylsulfonyl)imide ([emim⁺][Tf₂N^?]) and 1-butyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide ([bmim⁺][Tf₂N^?]) within a temperature range of 298 K ≤ T ≤ 368 K and a pressure range of 0.1 MPa ≤ p ≤ 100 MPa. The self-exchange reaction of the redox couple [TTF/TTF^?+] has been found to be diffusion-controlled in the used ionic liquids over the entire temperature range. The observed rate constants in ionic liquids at higher pressures are larger than those predicted by common diffusion, and suggest that the electron transfer takes place within a solvent cage. Also, the self-exchange reaction of the [TTF/TTF^?+] redox couple in classical solvents (dimethylphthalate (DMP) and acetonitrile) was investigated and compared to the results with those obtained in ionic liquids. The high viscosity of the ionic liquids makes it difficult to extract the electron transfer rate constants reliably, making interpretation within the framework of the Marcus Theory impossible.     

Microplasma-Based Detectors for Gas Chromatography: Current Status and Future Trends

Abstract: Microplasma is a useful detector for analyzing the effluent of gas chromato-graphy due to its remarkable capacity for portability, high sensitivity, and excellent multielement selectivity. Compared to classical detectors, microplasma detectors have the advantages of small size, low cost, and low energy consumption in design and operation. We aim to provide an overview of microplasma detectors and show their applications in various chemical analyses. The operational characteristics and analytical performance of different microplasma detectors, such as capacitively coupled microplasma, glow discharge microplasma, and microhollow-cathode microplasma, are presented in detail to reveal the current status of microplasma detectors for gas chromatography. In addition, several approaches for the design of microplasma are discussed and the future trends in the development of microplasma detectors are highlighted at the end of this review. Various applications of microplasma detectors for gas chromatography systems are also presented in this review.     

Dimensions and units in electrodynamics

We sketch the foundations of classical electrodynamics, in particular the transition that took place when Einstein, in 1915, succeeded to formulate general relativity. In 1916 Einstein demonstrated that, with a choice of suitable variables for the electromagnetic field, it is possible to put Maxwells equation into a form that is covariant under general coordinate transformations. This unfolded, by basic contributions of Kottler, Cartan, van Dantzig, Schouten & Dorgelo, Toupin & Truesdell, and Post, to what one may call premetric classical electrodynamics. This framework will be described shortly. An analysis is given of the physical dimensions involved in electrodynamics and subsequently the question of units addressed. It will be pointed out that these results are untouched by the generalization of classical to quantum electrodynamics (QED). We compare critically our results with those of L.B. Okun which he had presented at a recent conference.     

What a Classical r-Matrix Really Is

Abstract

To my friend and colleague K.C. Reddy on occasion of his retirement.

The notion of classical r-matrix is re-examined, and a definition suitable to differential (-difference) Lie algebras, – where the standard definitions are shown to be deficient, – is proposed, the notion of an O-operator. This notion has all the natural properties one would expect form it, but lacks those which are artifacts of finite-dimensional isomorpisms such as not true in differential generality relation End (V ) V ^? ? V for a vector space V . Examples considered include a quadratic Poisson bracket on the dual space to a Lie algebra; generalized symplectic-quadratic models of such brackets (aka Clebsch representations); and Drinfel’d’s 2-cocycle interpretation of nondegenate classical r-matrices.     

The atomic scale structure of saccharose-based carbons

Abstract

Activated carbons (ACs) have a wide range of applications, in which the largely expanded specific surface plays a major role. The question of their structure came back to the limelight with the discovery of nanotubes fullerenes, which suggested that curved surfaces may be present in their structure and which incorporates well into the ideas of ACs porous structure. The source of those curved surfaces is atomic defects present inside the in-plane graphitic honeycomb lattice. Such defects have a crucial influence on the macroscopic morphology as well as physical properties of the material. The activated carbon (AC) in this work was derived from carbonised saccharose by activation with NaOH. Both materials – before and after activation were investigated. The main methods used in this study are wide angle neutron scattering and wide angle X-ray scattering combined with computer simulations. Confirmation of the proposed structures was sought with high-resolution transmission electron microscopy and Raman scattering. In this case, the use of classical crystallography to interpret experimental data was impossible due to the lack of periodic three-dimensional symmetry. Due to this fact, the data was analysed both in real and reciprocal space in the form of a pair correlation function and a structure factor. The experimental data were compared with calculated atomistic models. As a validation, the discrepancy factor between the theoretically and experimentally obtained functions was used. The presented innovative approach can be applied to different carbon materials with varying degrees of disorder.     

Size and concentration effects in the optical properties of alloyed ( Au x Ag 1 - x ) n and core-shell ( Ni x Ag 1 - x ) n embedded clusters

Optical properties of mixed clusters (Au_xAg _{1 - x} ) _n and (Ni_xAg _{1 - x} ) _n , produced by laser vaporization and embedded in an alumina matrix, are reported. The size effects are investigated for different concentrations (x = 0.25, 0.5 and 0.75) in the diameter range 2-4 nm. For alloyed clusters (Au_xAg _{1 - x} ) _n of a given size an almost linear evolution of the surface plasmon frequency ω _s with the concentration is observed (between those of pure gold and pure silver clusters). Moreover the blue-shift and the damping of the resonance with decreasing size is all the more important as the gold concentration in the particles increases. Such results are in agreement with theoretical calculations carried out in the frame of the time-dependent local-density-approximation (TDLDA) including an inner skin of ineffective screening and the porosity of the matrix. The optical response of (Ni_xAg _{1 - x} ) _n clusters exhibits a surface plasmon resonance in the same spectral range as the one observed for pure silver clusters, but considerably damped and broadened. For a given mean cluster size 3.0 nm, a blue-shift of the resonance is observed when increasing the nickel concentration (between x = 0.25 and x = 0.75). The results are in good qualitative agreement with classical predictions in the dipolar approximation, assuming a core-shell geometry. Received 21 November 2000     

Trace Analysis Using Position-Sensitive Detection in Magnetic Sector Mass Spectrometry

Abstract

A position-sensitive ion detection system for trace analysis with magnetic sector mass spectrometers is described in detail, with particular application to high temperature mass spectrometry. The detection system consists of two stacked microchannel plates (Chevron assembly) backed by a resistive anode encoder and associated electronics. The range of masses simultaneously detectable is m to 1.2m. For electron impact ionization of silver at an electron energy of 10.5 eV, the sensitivity is 1.6 × 10^?7 Pa, and the mass resolution is 260 at mass 80 (valley 10% of the peak height definition). Additional applications for the detection system are discussed.     

On Algebraic Integrability of the Deformed Elliptic Calogero-Moser Problem

Abstract

We discuss stationary solutions of the discrete nonlinear Schrödinger equation (DNSE) with a potential of the ? ⁴ type which is generically applicable to several quantum spin, electron and classical lattice systems. We show that there may arise chaotic spatial structures in the form of incommensurate or irregular quantum states. As a first (typical) example we consider a single electron which is strongly coupled with phonons on a 1D chain of atoms — the (Rashba)–Holstein polaron model. In the adiabatic approximation this system is conventionally described by the DNSE. Another relevant example is that of superconducting states in layered superconductors described by the same DNSE. Amongst many other applications the typical example for a classical lattice is a system of coupled nonlinear oscillators. We present the exact energy spectrum of this model in the strong coupling limit and the corresponding wave function. Using this as a starting point we go on to calculate the wave function for moderate coupling and find that the energy eigenvalue of these structures of the wave function is in exquisite agreement with the exact strong coupling result. This procedure allows us to obtain (numerically) exact solutions of the DNSE directly. When applied to our typical example we find that the wave function of an electron on a deformable lattice (and other quantum or classical discrete systems) may exhibit incommensurate and irregular structures. These states are analogous to the periodic, quasiperiodic and chaotic structures found in classical chaotic dynamics.     

Theory of gyro devices with thin electron beams (large-orbit gyrotrons)

It is shown for a precisely aligned electron beam of small thickness in a large-orbit gyrotron that high cyclotron harmonics (up to s⩽5) can be selectively excited with an electronic efficiency that is acceptable for some applications (1–10%). When the quality of the electron beam is high, the selective properties are maintained even for modes with high radial indices, raising hopes that this method can be used to obtain coherent radiation not only in the millimeter but also in the entire submillimeter wavelength range. A method for taking into account the space-charge effects is developed, and it is shown that the corresponding effects can be important at relatively small values of the electron pitch factor. The results of the analysis and preliminary experiments reveal the possibility of creating high-power compact sources of submillimeter radiation for the spectroscopy of various media, the diagnostics of dense plasmas, and some other applications. Fiz. Tekh. Poluprovodn. 68, 91–98 (October 1998)     

Two-photon Absorption Properties of 9,10-Disubstituted 2,6-Bis(p-dihexylaminostyryl)Anthracene Derivatives. Effect of 9,10-Substituents

A series of 2,6-bis(p-dihexylaminostyryl)anthracence derivatives having phenyl, styryl, and phenylethynyl groups at 9,10-positions (1−4) have been synthesized and their two-photon cross-sections were determined. Overall, the wavelengths of the longest wavelength absorption band and emission spectra increase with increase in the conjugation length and the electron withdrawing ability of the 9,10-substituents. All compounds show two-photon cross sections in the range of 740−3940 GM at 780−960 nm, which increase significantly by the donor and acceptor groups at 9,10-positions. In addition, Ph and phenylethynyl groups are better when compared to the styryl group at the 9,10-positions in terms of the two-photon action cross section. From a practical perspective, 1a, 2a–c, and 4b showed significant two-photon action cross-section and are most useful for applications that use two-photon excited fluorescence.     

Substituent effects on the photophysical properties of amino-aurone-derivatives

ABSTRACT

Aurones are potential candidates to be employed as fluorescent probes or as pharmacophores for biological applications. This work describes a density functional theory (DFT) and time-dependent -DFT study at the PBE0/6-31?+?G(d) level of theory to analyse the structural, electronic and photophysical properties of a series of new proposed 4′-amine-aurone derivatives in its E and Z isomeric conformations. The maximum absorption wavelength of the proposed aurones appears in the range 390???514?nm, while the most allowed emission pathways were computed in the range 493–530?nm. The bathochromic shift of these compounds with respect to the non-substituted aurone is modulated by the acceptor strength of the added 4-substituents, in addition to the ability of the substituents to localise the frontier molecular orbitals over the acceptor benzofuranone moiety without losing the tricyclic planarity, which favours the push–pull nature of these molecules. The influence of the 4-substituent is also evidenced in the Stokes shifts for the whole series; as the electron-withdrawing character of the 4-substituents enhances, higher is the polarisation of the structure resulting in higher Stokes shifts. As a result, -CF₃ and -NO₂ substituents were responsible of larger Stokes shifts, then compounds containing these substituents are proposed as potential fluorescence probes for useful applications in biological systems.     

Spectroscopic manifestations of phase changes in CaAr n clusters: finite size effects

The finite temperature optical spectroscopy of CaAr_n clusters in the range 6 n 146 is investigated using a Diatomics-In-Molecule (DIM) Hamiltonian and classical parallel tempering Monte Carlo simulations. The absorption spectrum is calculated in the vertical approximation at various temperatures between 2 K and 50 K. Several typical situations are reported. CaAr₆ shows a strong thermal broadening and shift of the spectral lines, possibly associated with isomerization. CaAr₁₃ only shows some broadening. CaAr₃₇ exhibits features corresponding to coexisting isomers at low temperature. Finally, the abrupt changes in the absorption spectrum in CaAr₁₄₆ at about 20 K are indicative of surface diffusion.     

Vacuum splitting of the energy levels of a system consisting of an atom and a dielectric microsphere

Expressions are found for the vacuum splitting of the energy levels of a system consisting of a two-level atom and a dielectric microsphere. These expressions coincide with those obtained from a purely classical approach. Zh. éksp. Teor. Fiz. 111, 44–51 (Janaury 1997)