Table of contents

We examine the classical contents of quantum games. It is shown that a quantum strategy can be interpreted as a classical strategy with effective density-dependent game matrices composed of transposed matrix elements. In particular, successful quantum strategies in dilemma games are interpreted in terms of a symmetrized game matrix that corresponds to an altruistic game plan.

We investigate the influence of nonstationary 1/f^μ noise, produced by interacting defects, on a quantum two-level system. Adopting a simple phenomenological model for this noise we describe exactly the corresponding dephasing in various regimes. The nonstationarity and pronounced non-Gaussian features of this noise induce new anomalous dephasing scenarii. Beyond a history-dependent critical coupling strength, the dephasing time exhibits a strong dependence on the age of the noise and the decay of coherence is not exponential.

We introduce three measures which quantify the degree to which quantum systems possess the robustness exhibited by classical systems when subjected to continuous observation. Using these we show that for a fixed environmental interaction the level of robustness depends on the measurement strategy, or unravelling, and that no single strategy is maximally robust in all ways.

A Turing mode in an extended periodically forced oscillatory system can change the classical resonance boundaries of a single forced oscillator. Using the normal form equation for forced oscillations, we identify a Hopf-Turing bifurcation point around which we perform a weak nonlinear analysis. We show that resonant standing waves can exist outside the 2:1 resonance region of uniform oscillations, and non-resonant mixed-mode oscillations may prevail inside the resonance region.

Two fundamental notions of classical chemical kinetics—the "Chemical Equilibrium" and the "Law of Mass Action"—are re-examined here for reversible diffusion-limited reactions (DLR), on the example of association/dissociation A + A⇌B reactions. We consider a general model with long-ranged elementary reaction rates, such that any pair of A particles, separated by distance μ, may react at a rate k₊(μ), and any B may dissociate at a rate k₋(λ) into a geminate pair of A's separated by distance λ. Within an exact analytical approach, we show that the state attained by reversible DLR at t = ∞ is generally not a true thermodynamic equilibrium, but rather a non-equilibrium steady state, and that the Law of Mass Action is invalid. The classical picture holds only in case when the ratio k₊(μ)/k₋(μ) is independent of μ for any μ.

We propose a mechanism to give mass to tensor matter field which preserves the U(1) symmetry. We introduce a complex vector field that couples with the tensor in a topological term. We also analyze the influence of the kinetic terms of the complex vector in our mechanism.

The "square root" of the interacting Dirac equation is constructed. The obtained equations lead to the Yang-Mills superfield with the appropriate equations of motion for the component fields.

This paper presents a study of void probability scaling of medium-energy target protons emitted in ²⁴Mg-AgBr interaction at 4.5 AGeV in terms of their emission angle (θ). The scaling is best revealed in the phase space region for which cos θ = − 0.3 to cos θ = 0.7 and does not hold good for the total region of phase space. Fractal study reveals an interesting observation. A multifractal nature of the particle spectra has been observed in whole phase space whereas monofractal proton emission is evident in the phase space where the void probability scaling is valid.

The continuum-distorted-wave–Born-initial-state (CDW-BIS) approximation for the description of single-electron capture from helium-like atomic systems by completely stripped projectiles is presented. The theoretical total cross-sections for charge exchange in α-He and p-Li⁺ collisions are reported in the energy range 50–2000 keV/amu. We also report the results obtained by means of the continuum-distorted-wave–Born-final-state (CDW-BFS) approximation. Detailed computations for differential cross-sections are performed for p-He collisions at 500 and 200 keV. A comparison between the four-body one-channel distorted-wave approximation and three-body distorted-wave (CDW-3B) approximation is made for differential cross-sections at 200 keV. The validity of our findings is critically assessed in comparison with the available experimental data.

We generalize the invariant imbedding theory of wave propagation and derive new invariant imbedding equations for the propagation of an arbitrary number of coupled waves of any kind in arbitrarily inhomogeneous stratified media, where the wave equations are effectively one-dimensional. By doing this, we transform the original boundary value problem of coupled second-order differential equations to an initial value problem of coupled first-order differential equations, which makes the numerical solution of the coupled wave equations much easier. Using the invariant imbedding equations, we are able to calculate the matrix reflection and transmission coefficients and the wave amplitudes inside the inhomogeneous media exactly and efficiently. We establish the validity and the usefulness of our results by applying them to the propagation of circularly polarized electromagnetic waves in one-dimensional photonic crystals made of isotropic chiral media. We find that there are three kinds of bandgaps in these structures and clarify the nature of these bandgaps by exact calculations.

Based on Sirovich's two-fluid kinetic theory and on a dodecagonal discrete-velocity model, a two-dimensional 61-velocity finite-difference lattice Boltzmann method for the complete Navier-Stokes equations of binary fluids is formulated. Previous constraints, in most existing lattice Boltzmann methods, on the studied systems, like isothermal and nearly incompressible, are released within the present method. This method is designed to simulate compressible and thermal binary-fluid mixtures. The validity of the proposed method is verified by investigating i) the Couette flow and ii) the uniform relaxation process of the two components.

An adsorption-induced anchoring transition was found by confining liquid-crystal hydrophobic aerosil dispersions to cylindrical pores. The aerosil effects on the director configurations and on the orientational-order wetting at the pore walls were determined by DNMR. The aerosil spheres are adsorbed at the pore wall, hindering the planar anchoring and inducing an axial-to-radial structural transition dependent on increasing aerosil density. The orientational-order surface wetting in the isotropic phase is modified by the aerosil-introduced disorder from quasi-complete to partial to non-wetting.

We consider the voter model dynamics in random networks with an arbitrary distribution of the degree of the nodes. We find that for the usual node-update dynamics the average magnetization is not conserved, while an average magnetization weighted by the degree of the node is conserved. However, for a link-update dynamics the average magnetization is still conserved. For the particular case of a Barabási-Albert scale-free network, the voter model dynamics leads to a partially ordered metastable state with a finite-size survival time. This characteristic time scales linearly with system size only when the updating rule respects the conservation law of the average magnetization. This scaling identifies a universal or generic property of the voter model dynamics associated with the conservation law of the magnetization.

We describe spatio-temporal correlations and heterogeneities in a kinetically constrained glassy model, the Kob-Andersen model. The kinetic constraints of the model alone induce the existence of dynamic correlation lengths, that increase as the density ρ increases, in a way compatible with a double-exponential law. We characterize in detail the trapping time correlation length, the cooperativity length, and the distribution of persistent clusters of particles. This last quantity is related to the typical size of blocked clusters that slow down the dynamics for a given density.

A statistical mechanical model is presented to explain recent atomic force microscope (AFM) measurements on the equilibrium forces on a polymer chain adsorbed on a surface with one end attached to the AFM tip. We explore the dependence of this adsorption force on the depth and range of the surface potential and the characteristics of the polymer chain. We show that the force distribution is likely due to energetic surface inhomogeneities. The effect of thermodynamic force fluctuations is also discussed.

Spurious real solutions k_S ⩾ 1 Å⁻¹ of the bulk k•p Hamiltonian for semiconductors can lead to spurious bands and nonnormalizable wave functions in the envelope function approximation (EFA). Since physical observables cannot depend on layer width variations on the scale of 1 Å—less than a typical interface width or the precision of defining an interface—we form coherent superpositions of spurious real solutions that satisfy boundary conditions with interface boundaries varying on the scale of k_S⁻¹. The superposition leads to a total destructive interference, which demonstrates that real spurious solutions do not contribute to the envelope function away from interfaces. In the interfacial region, we show that real spurious solutions should be replaced with evanescent solutions that decay within k_S⁻¹. The present technique is demonstrated in a model case and in a superlattice calculation using the 8 × 8 EFA.

We study topological aspects of a compact lattice superconductor, and show that the characteristic energy splitting, Δ, between almost degenerate ground states, is simply related to a novel order parameter , which is closely related to large Wilson loops. Using Monte Carlo methods, we study the scaling properties of close to the deconfining phase transition, and conclude that Δ ∼ e^−L/ξ, where L is the size of the system, thus giving quantitative support to the vortex tunneling scenario proposed by Wen.

The low-temperature specific heat of electron-doped (n-type) infinite-layer cuprate superconductor Sr_0.9La_0.1CuO₂ was measured. The quasiparticle density of states (DOS) in the mixed state is found to be consistent with the predictions of the s-wave pairing symmetry, and agree very well with the earlier results from tunnelling measurement. This is contrary to the prediction of d-wave symmetry, which has been confirmed for the hole-doped (p-type) cuprates. Our results indicate that the electronic DOS in the mixed state are mainly contributed by the vortex core area in the present sample.

We investigate the experimental detection of the electromagnetic radiation generated in the fast magnetization reversal in Mn₁₂-acetate at low temperatures. In our experiments we used large single crystals and assemblies of several small single crystals of Mn₁₂-acetate placed inside a cylindrical stainless-steel waveguide in which an InSb hot-electron device was also placed to detect the radiation. All this was set inside a SQUID magnetometer that allowed to change the magnetic field and measure the magnetic moment and the temperature of the sample as the InSb detected simultaneously the radiation emitted from the molecular magnets. Our data show a sequential process in which the fast inversion of the magnetic moment first occurs, then the radiation is detected by the InSb device, and finally the temperature of the sample increases during 15 ms to subsequently recover its original value in several hundred milliseconds.

Subjecting a non-interacting mesoscopic ring (MR) to a linearly polarized half-cycle electromagnetic pulse results in a non-uniform, non-equilibrium coherent population of electronic states. A post-pulse charge polarization of the ring is then created within few picoseconds and sustains for times determined by the relaxation time scale. These conclusions are the results of a theoretical analysis of the electronic quantum dynamics of a MR subjected to unipolar pulses. Methods to trace experimentally the charge polarization build-up are suggested.

We report on the structural properties of mixed aggregates made from rare-earth inorganic nanoparticles (radius 20 Å) and polyelectrolyte-neutral block copolymers in aqueous solutions. Using scattering experiments and Monte Carlo simulations, we show that these mixed aggregates have a hierarchical core-shell microstructure. The core is made of densely packed nanoparticles and it is surrounded by a corona of neutral chains. This microstructure results from a process of controlled association and confers to the hybrid aggregates a remarkable colloidal stability.

The dynamics of two-dimensional suspensions of Brownian rods which are driven by an external torque are explored by computer simulation and instability theory. For increasing density the system self-organizes into a "T-structured fluid", where neighbouring rods preferentially orient perpendicular to each other until an overlap density is reached. Then a sharp jamming transition occurs towards a dynamically blocked state with parallel neighbouring rods.

Scientific communities are characterized by strong stratification. The highly skewed frequency distribution of citations of published scientific papers suggests a relatively small number of active, cited papers embedded in a sea of inactive and uncited papers. We propose an analytically soluble model which allows for the death of nodes. This model provides an excellent description of the citation distributions for live and dead papers in the SPIRES database. Further, this model suggests a novel and general mechanism for the generation of power law distributions in networks whenever the fraction of active nodes is small.

Personal income distribution in the USA has a well-defined two-class structure. The majority of population (97–99%) belongs to the lower class characterized by the exponential Boltzmann-Gibbs ("thermal") distribution, whereas the upper class (1–3% of the population) has a Pareto power law ("superthermal") distribution. By analyzing income data for 1983–2001, we show that the "thermal" part is stationary in time, save for a gradual increase of the effective temperature, whereas the "superthermal" tail swells and shrinks following the stock market. We discuss the concept of equilibrium inequality in a society, based on the principle of maximal entropy, and quantitatively show that it applies to the majority of population.

Erratum of Europhys. Lett.68 p. 846.