Interstitialcy theory of simple condensed matter

A simple, more physical and compelling version of the Interstitialcy Theory of Simple Condensed Matter than that given previously is provided here. Also, computer simulation and direct and indirect experimental evidence is updated and reviewed. The theory is based on the properties of an interstitial in the interstitialcy, sometimes known as the dumbbell configuration. A free energy is derived, taking account of the unusually large shear susceptibility and vibrational entropy of the dumbbell to find the thermodynamic and kinetic properties of simple liquids and glasses. The connection between theory and experiment for some of the more notable properties of simple condensed matter found later is also discussed. The direct visual observation of interstitial diffusion to the surface in platinum near 20 K in irradiated thin films by Morgenstern et al. [M. Morgenstern, T. Michely, G. Comsa, Phys. Rev. Lett. 79, 1305 (1997)] is found to be sufficient compelling evidence for the interstitialcy theory.     

Methods of topological obstruction theory in condensed matter physics

The notion of relative topological textures — nonuniform states of the general type in condensed (ordered) media — is introduced. For the classification of such states, an effective method is proposed which is based on the topological obstruction theory. The examples of relative topological textures are examined within the framework of the approach studied here.     

Mutual Chern-Simons theory and its applications in condensed matter physics

In this paper, the mutual Chern-Simons (MCS) theory is introduced as a new kind of topological gauge theory in 2+1 dimensions. We use the MCS theory in gapped phase as an effective low energy theory to describe the Z ₂ topological order of the Kitaev-Wen model. Our results show that the MCS theory can catch the key properties for the Z ₂ topological order. On the other hand, we use the MCS theory as an effective model to deal with the doped Mott insulator. Based on the phase string theory, the t-J model reduces to a MCS theory for spinons and holons. The related physics in high T _c cuprates is discussed.      

Estimating perturbative coefficients in high-energy physics and condensed matter theory

Using our method to estimate perturbative coefficients in quantum field theory (QFT), we consider several examples in high-energy physics and condensed matter theory. The results, in all cases, are remarkably good for the known terms. We also predict the values of as yet unknown terms. Moreover, we consider the general convergence properties of asymptotic series in QFT.     

Solitons in condensed matter: A paradigm

For this new journal dealing with nonlinear phenomena we review the setting of several important current problems in the physics of condensed matter (solids, liquids). We show how the concepts embodied in the mathematical analysis of solitons provide systematic new insight (i.e., a paradigm) into a central question: what are the important physical configurations in nonlinear condensed systems? Following these general issues we summarize the analysis of the dynamics and equilibrium thermodynamics (i.e., statistical mechanics) of non-linear one-dimensional model systems, and we indicate how the solitonic configurational phenomenology provides a basis for dynamic effects which are seen both experimentally and in molecular dynamics computer simulations. Many problems in condensed matter differ from the more familiar nonlinear mechanical or hydrodynamic applications in that finite temperature thermal fluctuations must be considered along with systematic dynamics.     

Neutron-photon studies of condensed matter

A theory of simultaneous photon absorption and inelastic neutron scattering is developed by treating the photon and neutron-matter interactions perturbatively. The leading-order mixing between the interactions shows that the neutron scattering cross-section is proportional to the dynamic structure factor (or Van Hove function) evaluated at an energy that is enhanced by the photon energy. The photon induced modification of the scattering vector is negligible. Thus, the proposed technique affords the possibility of measuring the dynamic structure factor at large energies and modest wavevectors which is a domain that is usually difficult to access because of kinematic constraints. The theory is developed in detail for some models of nuclear and magnetic systems. The results show that, in most cases, the experiments are likely to demand the use of very high intensity light sources. A particularly promising application appears to be in the study of electron plasmas since, using readily available pulsed lasers, the neutron cross-section is comparable with that for pure magnetic scattering.     

Vierbein walls in condensed matter

The effective field, which plays the part of the vierbein in general relativity, can have topologically stable surfaces, vierbein domain walls, at which the effective contravariant metric is degenerate. We consider vierbein walls separating domains with flat spacetime which are not causally connected at the classical level. The possibility of a quantum mechanical connection between the domains is discussed. Pis’ma Zh. éksp. Teor. Fiz. 70, No. 11, 705–710 (10 December 1999) Published in English in the original Russian journal. Edited by Steve Torstveit.     

Non-linear phonon dispersion of condensed matter

The non-linear features of an almost uniform condensate is discussed. The appearance of non-linear waves implies non-linear phonon dispersion and the localized superfluid depletion suggests a view of multi-vortex configuration as non-linear wave trains.     

Generalized Debye-Falkenhagen energy in condensed matter

The thermodynamic perturbation theory of Stell, Rasaiah and Narang is generalized to the case of multi-component Stockmayer fluids. The effects of polarization by the permanent dipoles is included to first order and the perturbation series is summed approximately to all orders in the dipole moments by means of two Padé approximants. The two-body and triplet terms in the expansion have been evaluated by Monte Carlo integration for a specific choice of the reference Lennard-Jones mixture and the results are used to study systematically the effect of dipolar interactions on excess thermodynamic properties. The utility of a one-fluid theory based on the van der Waals model is investigated and it is shown that the approach is useful for obtaining semi-quantitative information on mixtures of weakly polar fluids. The special case of mixtures of hydrogen chloride and xenon is considered and it is shown that the potential model used is inadequate to account for the large deviations from ideality which are observed for this system.     

Measuring entanglement in condensed matter systems

We show how entanglement may be quantified in spin and cold atom many-body systems using standard experimental techniques only. The scheme requires no assumptions on the state in the laboratory, and a lower bound to the entanglement can be read off directly from the scattering cross section of neutrons deflected from solid state samples or the time-of-flight distribution of cold atoms in optical lattices, respectively. This removes a major obstacle which so far has prevented the direct and quantitative experimental study of genuine quantum correlations in many-body systems: The need for a full characterization of the state to quantify the entanglement contained in it. Instead, the scheme presented here relies solely on global measurements that are routinely performed and is versatile enough to accommodate systems and measurements different from the ones we exemplify in this work.     

Poisson brackets in condensed matter physics

A general method of deriving nonlinear equations of hydrodynamics for both normal liquid and superfluid ⁴He and ³He, equations of the elasticity theory, equations for spin waves in magnets and spin glasses, liquid crystals, and so on is described. The method is based on the use of the Poisson “hydrodynamic” brackets. Hydrodynamic brackets are on the one hand, a classical limit of quantum commutators, on the other hand, Poisson brackets of certain symmetry groups inherent in the given problem: groups of general coordinate transformations for hydrodynamics and elasticity theory, groups of local spin rotations for spin waves, etc. Along with well-known examples nonlinear equations of the elasticity theory for bodies with impurities, dislocations and disclinations, and equations of motion for spin glasses and multisublattice magnets are studied.     

Simulations: A tool for studying quantum condensed matter systems

Quantum Monte Carlo techniques provide a new method for studying the properties of condensed matter systems. A review of this approach and the type of information which it can provide is given. Talk presented at the Frontiers of Monte Carlo Meeting, Los Alamos National Laboratory, September, 1985.     

A model for the pressure dependence of diffusion in condensed matter

In the present paper, a model has been used to develop a simple relation to study the pressure dependence of self-diffusion in solids and liquids that has two adjustable parameters. The computation done in each substance is found to be in very good agreement with the experimental data. It is interesting to note that the present relation is also capable of giving the activation volume in solids and liquids. The activation volume computed in the solids is found to be in very good agreement with the data available.     

Topology of linked defects in condensed matter

The present paper contains a systematic study of several linked singularities in condensed matter. We introduce a hierarchy of conservation laws in terms of differential forms corresponding to a sequence of linking invariants so that we can distinguish nontrivial links possessing zero Gauss linking coefficients. We obtain a set of topological obstruction rules for links in nematics, cholesterics, and superfluid³He and⁴He.     

Structure of crystalline and paracrystalline condensed matter

The experience of microparacrystals, in intermediate stages between “perfect crystalline” and “amorphous structures,” and as “building bricks” in condensed matter, has become accepted as a basic physical concept. Their existence was proven by optical and x-ray diffraction studies. A review and summary of the following aspects is presented mainly for the benefit of scientists working in the field of polymers: (1) basic features of the paracrystal; (2) types of paracrystalline distortions and their effects on the reflection profiles of the x-ray diffraction pattern; (3) the physical basis of the theory of paracrystallinity; (4) experimental determination of the paracrystalline distortion parameter g, the crystallite size L_hkt , and the α? value; (5) x-ray diffraction evidence of the existence of microparacrystals; and (6) examples of electron microscope observations of paracrystals in polymers as well as in other materials.     

A new theory of elementary matter

This is the first of a series of articles that reviews and expands upon a new theory of elementary matter. This paper presents an exposition of the philosophical approach and its general implications. The ensuing explicit form of the mathematical expression of the theory and several applications in the atomic and elementary particle domains will be developed in the succeeding parts of this series.The theory is based on three axioms: the principle of general relativity, a generalized Mach principle, and a correspondence principle. The approach is basically a deterministic, relativistic field theory which fully incorporates the idea that any realistic physical system is in facta closed system, without separable parts. It is shown that the most primitive mathematical expression of this theory, following as anecessary consequence of its axioms, is in terms of a set of coupled nonlinear spinor field equations. Nevertheless, the exact formalism is constructed to asymptotically approach the quantum mechanical formalism for a many-particle system, in the limit of sufficiently small energy-momentum transfer among the components of the considered closed system. Thus, all of the mathematical predictions of nonrelativistic quantum mechanics are contained in this theory, as a mathematical approximation. However, predictions follow from the exact form of this theory (where energy-momentum transfer can be arbitrarily large) that are not contained in the quantum theory.