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DOE OSTI2011

The Wave Function and Quantum Reality

We investigate the meaning of the wave function by analyzing the mass and charge density distributions of a quantum system. According to protective measurement, a charged quantum system has effective mass and charge density distributing in space, proportional to the square of the absolute value of its wave function. In a realistic interpretation, the wave function of a quantum system can be taken as a description of either a physical field or the ergodic motion of a particle. The essential difference between a field and the ergodic motion of a particle lies in the property of simultaneity; a field exists throughout space simultaneously, whereas the ergodic motion of a particle exists throughout space in a time-divided way. If the wave function is a physical field, then the mass and charge density will be distributed in space simultaneously for a charged quantum system, and thus there will exist gravitational and electrostatic self-interactions of its wave function. This not only violates the superposition principle of quantum mechanics but also contradicts experimental observations. Thus the wave function cannot be a description of a physical field but be a description of the ergodic motion of a particle. For the later there is only a localized particle with mass and charge at every instant, and thus there will not exist any self-interaction for the wave function. It is further argued that the classical ergodic models, which assume continuous motion of particles, cannot be consistent with quantum mechanics. Based on the negative result, we suggest that the wave function is a description of the quantum motion of particles, which is random and discontinuous in nature. On this interpretation, the square of the absolute value of the wave function not only gives the probability of the particle being found in certain locations, but also gives the probability of the particle being there. The suggested new interpretation of the wave function provides a natural realistic alternative to the orthodox interpretation, and it also implies that the de Broglie-Bohm theory and many-worlds interpretation are wrong and the dynamical collapse theories are in the right direction by admitting wavefunction collapse.

71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSIC↗

DOE OSTI2011

Towards violation of Born's rule: description of a simple experiment

Recently a new model with hidden variables of the wave type was elaborated, so called prequantum classical statistical field theory (PCSFT). Roughly speaking PCSFT is a classical signal theory applied to a special class of signals - 'quantum systems'. PCSFT reproduces successfully all probabilistic predictions of QM, including correlations for entangled systems. This model peacefully coexists with all known no-go theorems, including Bell's theorem. In our approach QM is an approximate model. All probabilistic predictions of QM are only (quite good) approximations of 'real physical averages'. The latter are averages with respect to fluctuations of prequantum fields. In particular, Born's rule is only an approximate rule. More precise experiments should demonstrate its violation. We present a simple experiment which has to produce statistical data violating Born's rule. Since the PCSFT-presentation of this experiment may be difficult for experimenters, we reformulate consequences of PCSFT in terms of the conventional wave function. In general, deviation from Born's rule is rather small. We found an experiment amplifying this deviation. We start with a toy example. Then we present a more realistic example based on Gaussian states with very small dispersion.

71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSIC↗

DOE OSTI2011

Probing QCD at high energy via correlations

A hadron or nucleus at high energy or small x{sub Bj} contains many gluons and may be described as a Color Glass Condensate. Angular and rapidity correlations of two particles produced in high energy hadron-hadron collisions is a sensitive probe of high gluon density regime of QCD. Evolution equations which describe rapidity dependence of these correlation functions are derived from a QCD effective action.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗

DOE OSTI2011

Multicomponent Nonlinear Systems of Bose-Fermi Fields: Exact Solutions

We present families of stationary solutions for a multicomponent nonlinear system of two boson and N{sub f} fermion fields in terms of elliptic functions of modulus k. This system is an extention of models, describing Bose-Fermi mixtures in the mean field approximation. We also single out the particular cases when the quasiperiodic solutions become periodic ones. In the limit of sinusoidal external potential (k{yields}0) our solutions model periodic waves trapped in an optical lattice. The other limit k{yields}1 provides solutions expressed by hyperbolic functions (vector solitons). Thus we demonstrate that our system describes quasi-periodic and periodic waves, as well as solitons.

71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSIC↗

DOE OSTI2011

A Mathematical Base for Fibre Bundle Formulation of Lagrangian Quantum Field Theory

The paper contains a differential-geometric foundations for an attempt to formulate Lagrangian (canonical) quantum field theory on fibre bundles. In it the standard Hilbert space of quantum field theory is replace with a Hilbert bundle; the former playing a role of a (typical) fibre of the letter one. Suitable sections of that bundle replace the ordinary state vectors and the operators on the system's Hilbert space are transformed into morphisms of the same bundle. In particular, the field operators are mapped into corresponding field morphisms.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗

DOE OSTI2011

Levinson's theorem and higher degree traces for Aharonov-Bohm operators

We study Levinson-type theorems for the family of Aharonov-Bohm models from different perspectives. The first one is purely analytical involving the explicit calculation of the wave-operators and allowing to determine precisely the various contributions to the left hand side of Levinson's theorem, namely, those due to the scattering operator, the terms at 0-energy and at energy +{infinity}. The second one is based on non-commutative topology revealing the topological nature of Levinson's theorem. We then include the parameters of the family into the topological description obtaining a new type of Levinson's theorem, a higher degree Levinson's theorem. In this context, the Chern number of a bundle defined by a family of projections on bound states is explicitly computed and related to the result of a 3-trace applied on the scattering part of the model.

97 MATHEMATICS AND COMPUTING↗

DOE OSTI2011

Exact solution of D{sub N}-type quantum Calogero model through a mapping to free harmonic oscillators

We solve the eigenvalue problem of the D{sub N}-type of Calogero model by mapping it to a set of decoupled quantum harmonic oscillators through a similarity transformation. In particular, we construct the eigenfunctions of this Calogero model from those of bosonic harmonic oscillators having either all even parity or all odd parity. It turns out that the eigenfunctions of this model are orthogonal with respect to a nontrivial inner product, which can be derived from the quasi-Hermiticity property of the corresponding conserved quantities.

71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSIC↗

DOE OSTI2012

Highly ordered self-assembled nanoscale periodic faceting in GaAs(631) homoepitaxial growth

We report on the self-assembly of large-order-correlated nanoscale faceting on GaAs(631)A substrates grown by molecular beam epitaxy. The surface morphology of the grown samples as a function of the growth temperature and the As-beam equivalent pressure was studied using atomic force microscopy. A two-dimensional autocorrelation function analysis was performed in order to quantitatively determine the uniformity of the surface corrugation. By optimizing the growth conditions, correlated faceted areas as large as 1.7 Multiplication-Sign 1.7 {mu}m{sup 2} are obtained. The highly ordered surface corrugation discussed here provides useful insights to prepare highly ordered facet planes for the self organized growth of quantum wires.

36 MATERIALS SCIENCE↗

DOE OSTI2015

Synthesis and characterization of sulfonate polystyrene-lignosulfonate-alumina (SPS-LS-Al{sub 2}O{sub 3}) polyblends as electrolyte membranes for fuel cell

The new type of electrolyte membrane materials has been prepared by blend sulfonated polystyrene (SPS), lignosulfonate (LS), and alumina (SPS-LS-Al{sub 2}O{sub 3}) by casting polymer solution. The resulting polymer electrolyte membranes were then characterized by functional groups analysis, mechanical properties, water uptake, ion exchange capacity, and proton conductivity. SPS-LS-Al{sub 2}O{sub 3} membranes with alumina composition various have been proven qualitatively by analysis of functional groups. Increasing the Al{sub 2}O{sub 3} ratio resulted in higher ion exchange capacity (IEC), mechanical strength and proton conductivity, but water uptake decreased. The SPS-LS-Al{sub 2}O{sub 3} blend showed higher proton conductivity than Nafion 117.

36 MATERIALS SCIENCE↗

DOE OSTI2015

Surface roughening and scaling behavior of vacuum-deposited SnCl{sub 2}Pc organic thin films on different substrates

The evolution of surface morphology and scaling behavior of tin (IV) phthalocyanine dichloride (SnCl{sub 2}Pc) thin films grown on Si(100) and glass substrates have been studied using atomic force microscopy (AFM) and height-height correlation function analysis. X-ray diffraction measurement confirms the crystalline nature of the SnCl{sub 2}Pc thin film on glass substrate, while no crystallographic ordering is present for the film grown on Si substrate. The growth exponent β is found to be much larger for the film on glass substrate (0.48 ± 0.07) as compared to that on Si substrate (0.21 ± 0.08), which may be due to the high step-edge barrier, so-called Ehrlich-Schwöbel barrier, resulting in the upward dominant growth on glass substrate. From the 2D fast Fourier transform of AFM images and derived scaling exponents, we conclude that the surface evolution follows a mound like growth. These results imply the superiority of glass substrate over the Si substrate for the growth of device quality SnCl{sub 2}Pc thin film.

71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSIC↗

DOE OSTI2016

Synchronization properties of coupled chaotic neurons: The role of random shared input

Spike-time correlations of neighbouring neurons depend on their intrinsic firing properties as well as on the inputs they share. Studies have shown that periodically firing neurons, when subjected to random shared input, exhibit asynchronicity. Here, we study the effect of random shared input on the synchronization of weakly coupled chaotic neurons. The cases of so-called electrical and chemical coupling are both considered, and we observe a wide range of synchronization behaviour. When subjected to identical shared random input, there is a decrease in the threshold coupling strength needed for chaotic neurons to synchronize in-phase. The system also supports lag–synchronous states, and for these, we find that shared input can cause desynchronization. We carry out a master stability function analysis for a network of such neurons and show agreement with the numerical simulations. The contrasting role of shared random input for complete and lag synchronized neurons is useful in understanding spike-time correlations observed in many areas of the brain.

71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSIC↗

DOE OSTI2019

A simulation-based model for understanding the time dependent x-ray drive asymmetries and error bars in indirectly driven implosions on the National Ignition Facility

Time-dependent low-mode asymmetries are believed to play a leading role in limiting the performance of current inertial confinement fusion implosions on the National Ignition Facility (NIF) [E. I. Moses et al., Phys. Plasmas 16, 041006 (2009)]. These long wavelength modes are initiated and driven by asymmetries in the x-ray flux from the hohlraum; however, the underlying hydrodynamics of the implosion also act to modify and amplify these asymmetries. Here we present here a simulation-based model connecting the time-dependent drive asymmetry seen by the capsule to the measured inflight and hot spot symmetries. This approach is based on a Green's function analysis for which we evaluate the response of the capsule to impulses of drive asymmetry at a series of times. Our model sheds new light on the sensitivity to the drive asymmetry of an imploded capsule, giving a new tool for design. Inverting the problem and finding the drive asymmetry needed to match the experimental data allow us to tightly constrain the drive asymmetry seen by the capsule, providing an error estimate on the result. Doing so, we are able to point out when and how the complex hohlraum simulations start to deviate from what they should obtain to match the experimental data. Ultimately, we project to use this model to make some experimental recommendations to fix the time-dependent low-mode asymmetry of indirectly driven implosions and identify additional measurements to further constrain the asymmetries with a view to improving target design on the NIF.

70 PLASMA PHYSICS AND FUSION TECHNOLOGY↗

DOE OSTI2023

Local cation ordering in compositionally complex Ruddlesden–Popper n = 1 oxides

The Ruddlesden–Popper (RP) layered perovskite structure is of great interest due to its inherent tunability, and the emergence and growth of the compositionally complex oxide (CCO) concept endows the RP family with further possibilities. Here, a comprehensive assessment of thermodynamic stabilization, local order/disorder, and lattice distortion was performed in the first two reported examples of lanthanum-deficient La n+1 B n O 3n+1 (n = 1, B = Mg, Co, Ni, Cu, Zn) obtained via various processing conditions. Chemical short-range order (CSRO) at the B-site and the controllable excess interstitial oxygen (δ) in RP-CCOs are uncovered by neutron pair distribution function analysis. Reverse Monte Carlo analysis of the data, Metropolis Monte Carlo simulations, and extended x-ray absorption fine structure analysis implies a modest degree of magnetic element segregation on the local scale. Further, ab initio molecular dynamics simulations results obtained from special quasirandom structure disagree with experimentally observed CSRO but confirm Jahn–Teller distortion of CuO 6 octahedra. These findings highlight potential opportunities to control local order/disorder and excess interstitial oxygen in layered RP-CCOs and demonstrate a high degree of freedom for tailoring application-specific properties. They also suggest a need for expansion of theoretical and data modeling approaches in order to meet the innate challenges of CCO and related high-entropy phases.

36 MATERIALS SCIENCE↗

DOE OSTI2020

Dimer interaction in the Hv1 proton channel

The voltage-gated proton channel Hv1 is a member of the voltage-gated ion channel superfamily, which stands out in design: It is a dimer of two voltage-sensing domains (VSDs), each containing a pore pathway, a voltage sensor (S4), and a gate (S1) and forming its own ion channel. Opening of the two channels in the dimer is cooperative. Part of the cooperativity is due to association between coiled-coil domains that extend intracellularly from the S4s. Interactions between the transmembrane portions of the subunits may also contribute, but the nature of transmembrane packing is unclear. Using functional analysis of a mutagenesis scan, biochemistry, and modeling, we find that the subunits form a dimer interface along the entire length of S1, and also have intersubunit contacts between S1 and S4. These interactions exert a strong effect on gating, in particular on the stability of the open state. Our results suggest that gating in Hv1 is tuned by extensive VSD–VSD interactions between the gates and voltage sensors of the dimeric channel.

59 BASIC BIOLOGICAL SCIENCES↗

DOE OSTI2020

The early-stage growth and reversibility of Li electrodeposition in Br-rich electrolytes

Significance Spatial variations in chemical composition and transport properties of the material phases (interphases) formed on reactive metals in liquid electrolytes are thought to be responsible for the propensity of metal battery electrodes to electrodeposit in irregular, nonplanar morphologies. Equilibrium theoretical calculations using joint density functional analysis in vacuum and generic liquid media indicate that in-plane transport at such interphases is enhanced substantially if LiX (X = Br > Cl > F) species predominate. This study employs optical visualization experiments and nucleation theory to experimentally investigate nucleation and early-stage growth dynamics of metallic lithium in electrolytes enriched with LiBr. It is shown that the Li-Br–rich interphases formed profoundly alter the morphology of Li electrodeposits by enhancing Li-ion surface diffusion.

25 ENERGY STORAGE↗

DOE OSTI2022

Molecular determinants of pH sensing in the proton-activated chloride channel

In response to acidic pH, the widely expressed proton-activated chloride (PAC) channel opens and conducts anions across cellular membranes. By doing so, PAC plays an important role in both cellular physiology (endosome acidification) and diseases associated with tissue acidosis (acid-induced cell death). Despite the available structural information, how proton binding in the extracellular domain (ECD) leads to PAC channel opening remains largely unknown. Here, through comprehensive mutagenesis and electrophysiological studies, we identified several critical titratable residues, including two histidine residues (H130 and H131) and an aspartic acid residue (D269) at the distal end of the ECD, together with the previously characterized H98 at the transmembrane domain–ECD interface, as potential pH sensors for human PAC. Mutations of these residues resulted in significant changes in pH sensitivity. Some combined mutants also exhibited large basal PAC channel activities at neutral pH. By combining molecular dynamics simulations with structural and functional analysis, we further found that the β12 strand at the intersubunit interface and the associated “joint region” connecting the upper and lower ECDs allosterically regulate the proton-dependent PAC activation. Our studies suggest a distinct pH-sensing and gating mechanism of this new family of ion channels sensitive to acidic environment.

59 BASIC BIOLOGICAL SCIENCES↗

DOE OSTI2012

A Salmonella typhimurium-translocated Glycerophospholipid:Cholesterol Acyltransferase Promotes Virulence by Binding to the RhoA Protein Switch Regions

Salmonella enterica serovar typhimurium translocates a glycerophospholipid: cholesterol acyltransferase (SseJ) into the host cytosol after its entry into mammalian cells. SseJ is recruited to the cytoplasmic face of the host cell phagosome membrane where it is activated upon binding the small GTPase, RhoA. SseJ is regulated similarly to cognate eukaryotic effectors, as only the GTP-bound form of RhoA family members stimulates enzymatic activity. Using NMR and biochemistry, this work demonstrates that SseJ competes effectively with Rhotekin, ROCK, and PKN1 in binding to a similar RhoA surface. The RhoA surface that binds SseJ includes the regulatory switch regions that control activation of mammalian effectors. These data were used to create RhoA mutants with altered SseJ binding and activation. This structure-function analysis supports a model in which SseJ activation occurs predominantly through binding to residues within switch region II. We further defined the nature of the interaction between SseJ and RhoA by constructing SseJ mutants in the RhoA binding surface. These data indicate that SseJ binding to RhoA is required for recruitment of SseJ to the endosomal network and for full Salmonella virulence for inbred susceptible mice, indicating that regulation of SseJ by small GTPases is an important virulence strategy of this bacterial pathogen. The dependence of a bacterial effector on regulation by a mammalian GTPase defines further how intimately host pathogen interactions have coevolved through similar and divergent evolutionary strategies.

Environmental Molecular Sciences Laboratory↗

DOE OSTI2014

An alternative mechanism for the methylation of phosphoethanolamine catalyzed by Plasmodium falciparum phosphoethanolamine methyltransferase

Here, the phosphobase methylation pathway catalyzed by the phosphoethanolamine methyltransferase in Plasmodium falciparum (PfPMT), the malaria parasite, offers an attractive target for anti-parasitic drug development. PfPMT methylates phosphoethanolamine (pEA) to phosphocholine for use in membrane biogenesis. Quantum mechanics and molecular mechanics (QM/MM) calculations tested the proposed reaction mechanism for methylation of pEA involving the previously identified Tyr-19–His-132 dyad, which indicated an energetically unfavorable mechanism. Instead, the QM/MM calculations suggested an alternative mechanism involving Asp-128. The reaction coordinate involves the stepwise transfer of a proton to Asp-128 via a bridging water molecule followed by a typical S n 2-type methyl transfer from S-adenosylmethionine to pEA. Functional analysis of the D128A, D128E, D128Q, and D128N PfPMT mutants shows a loss of activity with pEA but not with the final substrate of the methylation pathway. X-ray crystal structures of the PfPMT-D128A mutant in complex with S-adenosylhomocysteine and either pEA or phosphocholine reveal how mutation of Asp-128 disrupts a hydrogen bond network in the active site. The combined QM/MM, biochemical, and structural studies identify a key role for Asp-128 in the initial step of the phosphobase methylation pathway in Plasmodium and provide molecular insight on the evolution of multiple activities in the active site of the PMT.

59 BASIC BIOLOGICAL SCIENCES↗