A cluster algorithm for Potts models with fixed spin densitiesA cluster algorithm is presented for the simulation of the q-state Potts models in which the number of spins is conserved in each state. The algorithm constructs Fortuin-Kasteleyn cluster…R. P. Bikker, G. T. Barkema·May 3, 2000SaveLearn
Aharonov-Bohm spectral features and coherence lengths in carbon nanotubesThe electronic properties of carbon nanotubes are investigated in the presence of disorder and a magnetic field parallel or perpendicular to the nanotube axis. In the parallel field geometry, the…S. Roche, G. Dresselhaus, M. S. Dresselhaus et al.·May 3, 2000SaveLearn
Formation of Pairing Fields in Resonantly Coupled Atomic and Molecular Bose-Einstein CondensatesIn this paper, we show that pair-correlations may play an important role in the quantum statistical properties of a Bose-Einstein condensed gas composed of an atomic field resonantly coupled with a…M. Holland, J. Park, R. Walser·May 2, 2000SaveLearn
Trapped condensates of atoms with dipole interactionsWe discuss in detail properties of trapped atomic condensates with anisotropic dipole interactions. A practical procedure for constructing anisotropic low energy pseudo potentials is proposed and…S. Yi, L. You·May 2, 2000SaveLearn
Nonlinear acoustic and microwave absorption in disordered semiconductorsNonlinear hopping absorption of ultrasound and electromagnetic waves in amorphous and doped semiconductors is considered. It is shown that even at low amplitudes of the electric (or acoustic) field…M. Kirkengen, Y. M. Galperin·May 2, 2000SaveLearn
Scaling Behaviour of Developing and Decaying NetworksWe find that a wide class of developing and decaying networks has scaling properties similar to those that were recently observed by Barabási and Albert in the particular case of growing networks.…S. N. Dorogovtsev, J. F. F. Mendes·May 2, 2000SaveLearn
Mixed population Minority Game with generalized strategiesWe present a quantitative theory, based on crowd effects, for the market volatility in a Minority Game played by a mixed population. Below a critical concentration of generalized strategy players, we…P. Jefferies, M. Hart, N. F. Johnson et al.·May 2, 2000SaveLearn
Pseudogap in the Optical Spectra of UPd2Al3The in-plane optical conductivity of UPd2Al3 was measured at temperatures 2 K<T<300 K in the spectral range from 1 cm-1 to 40 cm-1 (0.14 meV to 5 meV). As the temperature decreases…M. Dressel, B. Gorshunov, N. Kasper et al.·May 2, 2000SaveLearn
Possible Triplet Electron Pairing and an Anisotropic Spin Susceptibility in Organic Superconductors (TMTSF)2 XWe argue that (TMTSF)2 PF6 compound under pressure is likely a triplet superconductor with a vector order parameter d(k) (da(k) ≠ 0, dc(k) = ?, db'(k) = 0); |da(k)| > |dc(k)|.…A. G. Lebed, K. Machida, M. Ozaki·May 2, 2000SaveLearn
Crossover from percolation to diffusionA problem of the crossover from percolation to diffusion transport is considered. A general scaling theory is proposed. It introduces phenomenologically four critical exponents which are connected by…D. N. Tsigankov, A. L. Efros·May 1, 2000SaveLearn
Eliminating the mean-field shift in multicomponent Bose-Einstein condensatesWe demonstrate that the nonlinear mean-field shift in a multi-component Bose-Einstein condensate may be eliminated by controlling the two-body interaction coefficients. This modification is achieved…E. V. Goldstein, M. G. Moore, H. Pu et al.·May 1, 2000SaveLearn
Parametric Quantum Resonances for Bose-Einstein CondensatesWe generalize recent work on parametric resonances for nonlinear Schrödinger (NLS) type equations to the case of three dimensional Bose-Einstein condensates at zero temperatures. We show the…P. G. Kevrekidis, A. R. Bishop, K. Ø. Rasmussen·May 1, 2000SaveLearn
Normal Stress Distribution of Rough Surfaces in ContactWe study numerically the stress distribution on the interface between two thick elastic media bounded by interfaces that include spatially correlated asperities. The interface roughness is described…Alex Hansen, Jean Schmittbuhl, G. George Batrouni et al.·May 1, 2000SaveLearn
Bose-Einstein condensation in trapped dipolar gasesWe discuss Bose-Einstein condensation in a trapped gas of bosonic particles interacting dominantly via dipole-dipole forces. We find that in this case the mean-field interparticle interaction and,…L. Santos, G. V. Shlyapnikov, P. Zoller et al.·Apr 30, 2000SaveLearn
Two-magnon Raman scattering in spin-ladder geometries and the ratio of rung and leg exchange constantsWe discuss ways in which the ratio of exchange constants along the rungs and legs of a spin-ladder material influences the two-magnon Raman scattering spectra and hence can be determined from it. We…P. J. Freitas, R. R. P. Singh·Apr 27, 2000SaveLearn
Correlation functions in the factorization approach of nonextensive quantum statisticsWe study the long range behavior of a gas whose partition function depends on a parameter q and it has been claimed to be a good approximation to the partition function proposed in the formulation of…Marcelo R. Ubriaco·Apr 27, 2000SaveLearn
Study of Macroscopic Coherence and Decoherence in the SQUID by Adiabatic InversionWe suggest a procedure for demonstrating quantum coherence and measuring decoherence times between different fluxoid states of a SQUID by using ``adiabatic inversion'', where one macroscopic…P. Silvestrini, L. Stodolsky·Apr 27, 2000SaveLearn
Emission Spectrum of a Dipole in a Semi-infinite Periodic Dielectric Structure: Effect of the BoundaryThe emission spectrum of a dipole embedded in a semi-infinite photonic crystal is calculated. For simplicity we study the case in which the dielectric function is sinusoidally modulated only along…A. G. Galstyan, M. E. Raikh, Z. V. Vardeny·Apr 26, 2000SaveLearn
Structure of Growing Networks: Exact Solution of the Barabasi--Albert's ModelWe generalize the Barabási--Albert's model of growing networks accounting for initial properties of sites and find exactly the distribution of connectivities of the network P(q) and the…S. N. Dorogovtsev, J. F. F. Mendes, A. N. Samukhin·Apr 26, 2000SaveLearn
Vertical Melting of a Stack of MembranesA stack of tensionless membranes with nonlinear curvature energy and vertical harmonic interaction is studied. At low temperatures, the system forms a lamellar phase. At a critical temperature, the…M. E. S. Borelli, H. Kleinert, Adriaan M. J. Schakel·Apr 26, 2000SaveLearn
Comment on ``Phase ordering in chaotic map lattices with conserved dynamics''Angelini, Pellicoro, and Stramaglia [Phys. Rev. E 60, R5021 (1999), cond-mat/9907149] (APS) claim that the phase ordering of two-dimensional systems of sequentially-updated chaotic maps with…Julien Kockelkoren, Hugues Chaté·Apr 26, 2000SaveLearn
Vortex shedding and drag in dilute Bose-Einstein condensatesAbove a critical velocity, the dominant mechanism of energy transfer between a moving object and a dilute Bose-Einstein condensate is vortex formation. In this paper, we discuss the critical velocity…T. Winiecki, B. Jackson, J. F. McCann et al.·Apr 26, 2000SaveLearn
Calculations of single particle spectra in density functional theoryIn the context of the density functional theory we consider the single particle excitation spectra of electron systems. As a result, we have related the single particle excitations with the…M. Ya. Amusia, V. R. Shaginyan·Apr 25, 2000SaveLearn
Physics of Fashion FluctuationsWe consider a market where many agents trade many different types of products with each other. We model development of collective modes in this market, and quantify these by fluctuations that scale…Raul Donangelo, Alex Hansen, Kim Sneppen et al.·Apr 25, 2000SaveLearn
Can a frustrated spin-cluster model describe the low-temperature physics of NaV2O5 ?Recent experimental evidence suggest the existence of three distinct V-valence states (V+4, V+4.5 and V+5) in the low-temperature phase of NaV2O5 in apparent discrepancy with the observed…Claudius Gros, Roser Valenti, J. V. Alvarez et al.·Apr 25, 2000SaveLearn