Revealing Bell’s nonlocality for unstable systems in high energy physics

Entanglement and its consequences—in particular the violation of Bell inequalities, which defies our concepts of realism and locality—have been proven to play key roles in Nature by many experiments for various quantum systems. Entanglement can also be found in systems not consisting of ordinary matter and light, i.e. in massive meson–antimeson systems. Bell inequalities have been discussed for these systems, but up to date no direct experimental test to conclusively exclude local realism was found. This mainly stems from the fact that one only has access to a restricted class of observables and that these systems are also decaying. In this Letter we put forward a Bell inequality for unstable systems which can be tested at accelerator facilities with current technology. Herewith, the long awaited proof that such systems at different energy scales can reveal the sophisticated “dynamical” nonlocal feature of Nature in a direct experiment gets feasible. Moreover, the role of entanglement and CP\mathcal{CP} violation, an asymmetry between matter and antimatter, is explored, a special feature offered only by these meson–antimeson systems.     

Combinatorial chemistry: oh what a decade or two can do

This short commentary takes a stroll through the early days of the field of combinatorial chemistry and molecular diversity. It offers a high-level perspective on the field’s beginnings—and its future—as it relates to journals, books, pioneers, and advances.     

On the Convergence of Cluster Expansions for Polymer Gases

We compare the different convergence criteria available for cluster expansions of polymer gases subjected to hard-core exclusions, with emphasis on polymers defined as finite subsets of a countable set (e.g. contour expansions and more generally high- and low-temperature expansions). In order of increasing strength, these criteria are: (i) Dobrushin criterion, obtained by a simple inductive argument; (ii) Gruber-Kunz criterion obtained through the use of Kirkwood-Salzburg equations, and (iii) a criterion obtained by two of us via a direct combinatorial handling of the terms of the expansion. We show that for subset polymers our sharper criterion can be proven both by a suitable adaptation of Dobrushin inductive argument and by an alternative—in fact, more elementary—handling of the Kirkwood-Salzburg equations. In addition we show that for general abstract polymers this alternative treatment leads to the same convergence region as the inductive Dobrushin argument and, furthermore, to a systematic way to improve bounds on correlations.     

Photoelectron diffraction: from phenomenological demonstration to practical tool

The potential of photoelectron diffraction—exploiting the coherent interference of directly-emitted and elastically scattered components of the photoelectron wavefield emitted from a core level of a surface atom to obtain structural information—was first appreciated in the 1970s. The first demonstrations of the effect were published towards the end of that decade, but the method has now entered the mainstream armoury of surface structure determination. This short review has two objectives: First, to outline the way that the idea emerged and the way this evolved in my own collaboration with Neville Smith and his colleagues at Bell Labs in the early years: Second, to provide some insight into the current state-of-the art in application of (scanned-energy mode) photoelectron diffraction to address two key issue in quantitative surface structure determination, namely, complexity and precision. In this regard a particularly powerful aspect of photoelectron diffraction is its elemental and chemical-state specificity.     

Interplay between classical and quantum signals: partial trace and measurement channels

We continue the study of similarities between quantum information theory and theory of classical Gaussian signals. The possibility of using quantum entropy for classical Gaussian signals was explored a long time ago. Recently we demonstrated that some basic quantum channels can be represented as linear transforms of classical Gaussian signals. Here we consider bipartite quantum systems and show that an important quantum channel given by the partial trace operation has a simple classical representation, namely, a coordinate projection of a classical “prequantum signal.” We also consider the classical signal realization of quantum channels corresponding to state transforms in the process of measurement. The latter induces a difficult interpretational problem — the output signal corresponding to one system depends on a measurement that has been done on the second system. This situation might be interpreted as a sign of quantum nonlocality, action at a distance. Although we do not exclude such a possibility, i.e., that, in complete accordance with Bell, the creation of a realistic prequantum model is impossible without action at a distance, we found another interpretation of this situation that is not related to quantum nonlocality.     

Cosmic rays in the heliosphere

Summary This is a rapporteur paper for the XXIV International Cosmic-Ray Conference covering topics of anomalous cosmic rays, shock acceleration, modulation and transport theory, cosmic-ray gradients, corotating interaction regions, coronal-mass ejections, and solar neutrinos. Among the highlights of the meeting are —conclusive proof that most anomalous cosmic rays are singly charged,—undisputed detection of anomalous cosmic-ray hydrogen,—discovery of unexpectedly large anisotropies of pickup ions,—observation of pronounced solar rotational modulation of cosmic-ray fluxes to the highest heliolatitudes (∼80°) probed by the Ulysses spacecraft, and—new measurements of modulation effects sensitive to particle charge sign. Rapporteur talk given at the XXIV International Cosmic-Ray Conference, Rome, August 28–September 8, 1995.     

Compatibility of Subsystem States

We examine the possible states of subsystems of a system of bits or qubits. In the classical case (bits), this means the possible marginal distributions of a probability distribution on a finite number of binary variables; we give necessary and sufficient conditions for a set of probability distributions on all proper subsets of the variables to be the marginals of a single distribution on the full set. In the quantum case (qubits), we consider mixed states of subsets of a set of qubits; in the case of three qubits we find quantum Bell inequalities—necessary conditions for a set of two-qubit states to be the reduced states of a mixed state of three qubits. We conjecture that these conditions are also sufficient.     

Structure of zinc-borate low-melting glasses derived from IR spectroscopy data

The IR spectra of glasses of the ZnO—SrO—B₂O₃ system with constant additions of PbO, Al₂O₃, and Li₂O (20 mol. % in sum) were studied. It is established that on replacement of B₂O₃ by ZnO, the structure of the glasses is characterized by the presence of groupings with the bridge bonds B^III— O—B^III, B^III—O—B^IV, B^IV—O—B^IV and end groups B^III— O⁻; ZnO practically exerts no influence on the coordination transition [BO₃] → [BO₄]. At a high content of ZnO, zinc ions are present in both a six-and a four-coordinated state. __________ Translated from Zhurnal Prikladnoi Spektroskopii, Vol. 72, No. 6, pp. 778–781, November–December, 2005.     

Glow-discharge-pumped broadband ultraviolet lamp

The optical characteristics of a UV broadband lamp that was excited by a longitudinal glow discharge and operated on Kr—Br₂—I₂, Xe—Br₂—I₂, and Kr—Xe—Br₂—I₂ mixtures are investigated. The interelectrode spacing in the lamp is 10 cm, the inner diameter of a discharge tube being 14 mm. The current-voltage characteristics, the emission spectra of the plasma, and the dependence of the intensity of spectral lines (the amplitude of radiation bands) on the power that was pumped into the plasma based on mixtures of various compositions and pressures, as well as the radiation power in the spectral range from 200 to 390 nm, are studied. __________ Translated from Zhurnal Prikladnoi Spektroskopii, Vol. 72, No. 6, pp. 840–842, November–December, 2005.     

Constructing lie algebras of first-order differential operators

Formulas for calculating vector fields — generators of groups of transformations to a uniform space — from specified structural constants are obtained. The problem of vector-field continuation — the construction of Lie algebras of inhomogeneous first-order differential operators — is considered. It is also shown that the existence of a nontrivial continuation is closely associated with the structure of the isotopic subalgebra and, in particular, that no nontrivial continuation exists for semisimple algebras. Omsk State University. Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 6, pp. 25–32, June, 1997.     

Photoconversion and photocatalytic activity of uranyl in acetone solutions

We have studied the effect of irradiation on the uranyl nitrate — acetone and uranyl perchlorate — acetone systems. We have established that when the uranyl perchlorate — acetone system is irradiated, polymerization of the acetone occurs and the catalyst for the process is excited uranyl complexes. In the polymer, uranium is found in the form of nanoclusters of pentavalent and tetravalent uranium, formed as a result of photochemical reactions. Polymerization does not occur in the uranyl nitrate — acetone system. We consider possible factors responsible for the noted differences. __________ Translated from Zhurnal Prikladnoi Spektroskopii, Vol. 74, No. 5, pp. 565–568, September–October, 2007.     

The wideband attenuation of short radio waves on mid-latitude paths during X-ray flares in January 2005

We present the results of the ionosphere oblique chirp sounding on the Cyprus—Nizhny Novgorod, Cyprus—Rostov-on-Don, and Moscow—Rostov-on-Don mid-latitude paths during X-ray flares in January 17, 19, and 20, 2005. It is found that during strong flares the blackout of short radio waves was observed over the entire frequency range of chirp sounding on the Cyprus—Nizhny Novgorod and Cyprus—Rostov-on-Don paths. Modeling of the electron-density profiles in the lower ionosphere based on absorption of short radio waves on the Moscow—Rostov-on-Don path at different stages of the decay of the X-ray radiation intensity is carried out. It is shown that at the instant corresponding to the maximum value of the flare radiation flux, the electron density in the lower ionosphere at altitudes 60–80 km increased by a factor of about 10 and 100 for flares with radiation flux densities 5·10⁻² and 3·10⁻¹ erg/(cm ²·s) in the wavelength range 0.5–4.0 Å which took place in January 19 and 20, respectively. __________ Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Radiofizika, Vol. 50, No. 1, pp. 1–8, January 2007.     

Some top-quark propertie s mea sured in $$p\bar p$$ colli sion s u sing CDF detector at √ s = 1.96 TeV (Review)

This review considers important properties of the top-quark. The top-quark decays before hadronization, and the spin information is directly transferred to the decay products. Therefore the structure of the weak interaction is investigated by measuring the helicity fractions, f, of the W boson—the top-quark decay product. Other investigations: search for the presence of V+A interaction, search for exotic top-quark charge — 4/3 and for t[`(t)]t\bar t — resonances—all of them, so far, were not found in the experiments — testifies against of going out of the Standard Model.     

Cosmic microwave background and first molecules in the early universe

Besides the Hubble expansion of the universe, the main evidence in favor of the big-bang theory was the discovery, by Penzias and Wilson, of the cosmic microwave background (hereafter CMB) radiation. In 1990, the COBE satellite (Cosmic Background Explorer) revealed an accurate black-body behavior with a temperature around 2.7 K. Although the microwave background is very smooth, the COBE satellite did detect small variations—at the level of one part in 100 000—in the temperature of the CMB from place to place in the sky. These ripples are caused by acoustic oscillations in the primordial plasma. While COBE was only sensitive to long-wavelength waves, the Wilkinson Microwave Anisotropy Probe (WMAP)—with its much higher resolution—reveals that the CMB temperature variations follow the distinctive pattern predicted by cosmological theory. Moreover, the existence of the microwave background allows cosmologists to deduce the conditions present in the early stages of the big bang and, in particular, helps to account for the chemistry of the universe. This report summarizes the latest measurements and studies of the CMB with the new calculations about the formation of primordial molecules. The PLANCK mission—planned to be launched in 2009—is also presented.     

Erosion of the GaAs target under irradiation by a high-power pulsed ion beam

The results of examination of the GaAs-target erosion under irradiation by a high-power pulsed ion beam are reported. In the experiments, use was made of a high-power pulsed ion source with the following parameters: ion energy — 250 keV, target current density — 350 A/cm², pulse duration — 80 ns, target energy density — up to 7 J/cm². The target erosion coefficient and its dependence on the number of successive pulses are measured. It is found that the surface roughness parameter is increased with the number of successive beam pulses. A regular structure of surface relief is observed to form in the case where the number of pulses > 20–40. __________ Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 1, pp. 66–70, January, 2007.     

Network robustness to targeted attacks. The interplay of expansibility and degree distribution

We study the property of certain complex networks of being both sparse and highly connected, which is known as “good expansion” (GE). A network has GE properties if every subset S of nodes (up to 50% of the nodes) has a neighborhood that is larger than some “expansion factor” φ multiplied by the number of nodes in S. Using a graph spectral method we introduce here a new parameter measuring the good expansion character of a network. By means of this parameter we are able to classify 51 real-world complex networks — technological, biological, informational, biological and social — as GENs or non-GENs. Combining GE properties and node degree distribution (DD) we classify these complex networks in four different groups, which have different resilience to intentional attacks against their nodes. The simultaneous existence of GE properties and uniform degree distribution contribute significantly to the robustness in complex networks. These features appear solely in 14% of the 51 real-world networks studied here. At the other extreme we find that ∼40% of all networks are very vulnerable to targeted attacks. They lack GE properties, display skewed DD — exponential or power-law — and their topologies are changed more dramatically by targeted attacks directed at bottlenecks than by the removal of network hubs.     

A discrete nonetheless remarkable brick in de Sitter: The “massless minimally coupled field”

Over the last ten years interest in the physics of de Sitter space—time has been growing very fast. Besides the supposed existence of a “de Sitterian period” in inflation theories, the observational evidence of an acceleration of the universe expansion (interpreted as a positive cosmological constant or a “dark energy” or some form of “quintessence”) has triggered a lot of attention in the physics community. A specific de Sitterian field called “massless minimally coupled field” (mmc) plays a fundamental role in inflation models and in the construction of the de Sitterian gravitational field. A covariant quantization of the mmc field, à la Krein—Gupta—Bleuler was proposed in Class. Quantum. Grav. 17, 1415 (2000). In this talk, we will review this construction and explain the relevance of such a field in the construction of a massless spin-2 field in de Sitter space—time.     

Evaluation and use of the Pd | SrCe0.95Yb0.05O3| Pd electrochemical reactor for equilibrium-limited hydrogenation reactions

The current — overpotential characteristics of the H₂ - Pd - SCY interphase have been studied at atmospheric total pressure and temparatures between 400 – 550 °C in the single chamber reactor — cell: Pd | SCY | Pd. The results of I−η measurements indicate that the apparent anodic and cathodic charge tranfer coefficients are equal to: α_a=α_c=0.5. The present results are compared to those obtained with the single — chamber reactor cell: Ag | SCY | Ag. A solid state proton (H⁺) conducting reactor — cell with Pd electrodes was tested for the ammonia synthesis from its elements at atmospheric pressure. At 570 °C, over 75% of the ectrochemically supplied hydrogen was converted into NH₃. The thermodynamic requirement for a high pressure process was eliminated. Paper presented at the 5th Euroconference on Solid State Ionics, Benalmádena, Spain, Sept. 13–20, 1998.