Hasil untuk "cond-mat.other"

Thomas Ruedas

It is shown that the SPOCK equation of state is equivalent to the Variable Polytrope Index equation of state.

Albert Samoilenka, Egor Babaev

We propose a generalization of the crystalline order: the ground state fractal crystal. We demonstrate that by deriving a simple continuous-space-discrete-field (CSDF) model whose ground state is a crystal where each unit cell is a fractal.

Lindsay J. DiStefano, Jessica C. Martinez, Elizabeth Crowley et al.

Cori T. Leonetti, Matt A. Hamada, Stephanie J. Laurer et al.

A Braginsky

In this paper we propose to describe the deformed state of a helimagnet in the magnetic field (A-phase) with a pair of variables: the order parameter which characterizes the magnetic density and the tensor of distortion. Such description corresponds to discontinuities in the magnetic sublattice of the helimagnet accompanied by appearance of dislocations. It is shown that the phase diagram we found for the helimagnet is analogous to the phase diagram of the superconductors of second kind in the magnetic field, where the A-phase is a counterpart of the superconducting mixed state with the Abrikosov vortices.

E. B. Sonin

This is a short review of theoretical and experimental studies of Tkachenko waves starting from their theoretical prediction by Tkachenko about 50 years ago up to their unambiguous experimental observation in the Bose--Einstein condensate of cold atoms.

Jacob E. Earp, W. Kraemer, R. Newton et al.

Alexander F. Goncharov, Viktor V. Struzhkin

Eremets and Troyan (Nature Mater. 10, 927-931 (2011)) claim that they produced the conducting liquid hydrogen state at 270 GPa and 295 K. Their evidence consists of disappearance of Raman signals, visual observations, and measurements of electrical conductivity in diamond anvil cells (DAC). However, there is no proof that the reported observations are due to transformations in hydrogen.

J Frenkel, J C Taylor

The validity of the Langevin equation (both classical and quantum) is studied in cases when not all the equations of motion are linear. In particular, a model is studied in which the interaction is bilinear in the environment variables. We conclude that the equation is valid only for frequencies close to the frequency of the system alone. If the equation of motion of the system alone is nonlinear, we are unable to find a condition for the validity of the Langevin equation.

Maciej Lewenstein, Boris A. Malomed

We present analytic expressions describing generation of the entanglement in collisions of initially uncorrelated quantum solitons. The results, obtained by means of the Born's approximation (for fast solitons), are valid for both integrable and non-integrable quasi-one-dimensional systems supporting soliton states.

Yu. V. Bludov, V. V. Konotop

It is shown that the one-dimensional nonlinear Schrödinger equation with a dissipative periodic potential, nonlinear losses and linear pump allow for the existence of stable nonlinear Bloch states which are attractors. The model describes a Bose-Einstein condensate with inelastic two- and three-body interactions loaded in an optical lattice with losses due to inelastic interactions of the atoms with photons.

R. Car, M. Parrinello, M. Payne

Daw-Wei Wang, Eugene Demler

We analyze theoretically the collective mode dispersion in multi-layer stacks of two dimensional dipolar condensates and find a strong enhancement of the roton instability. We discuss the interplay between the dynamical instability and roton softening for moving condensates. We use our results to analyze the decoherence rate of Bloch oscillations for systems in which the s-wave scattering length is tuned close to zero using Feshbach resonance. Our results are in qualitative agreement with recent experiments of Fattori {\it et al.} on $^{39}$K atoms.

V. Gurarie

This paper examines the problem of molecule production in an atomic fermionic gas close to an s-wave Feshbach resonance by means of a magnetic field sweep through the resonance. The density of molecules at the end of the process is derived for narrow resonance and slow sweep.

D. Wilcox, Tim Gebbie

M. Sales, H. Yoshino

We examine the sensitiveness of the free-energy landscape of a directed polymer in random media with respect to various kinds of infinitesimally weak perturbation including the intriguing case of temperature chaos. To this end, we combine the replica Bethe Ansatz approach outlined by Sales and Yoshino (e-print cond-mat/0112384), the mapping to a modified Sinai model, and numerically exact calculations by the transfer-matrix method. Our results imply that for all the perturbations under study there is a slow crossover from a weakly perturbed regime, where rare events take place, to a strongly perturbed regime at larger length scales beyond the so-called overlap length, where typical events take place leading to chaos, i.e., a complete reshuffling of the free-energy landscape. Within the replica space, the evidence for chaos is found in the factorization of the replicated partition function induced by infinitesimal perturbations. This is the reflex of explicit replica-symmetry breaking.

A. Emperador, M. Pi, M. Barranco et al.

We have employed time-dependent local-spin density theory to analyze the far-infrared transmission spectrum of InAs self-assembled nano-rings recently reported [A. Lorke et al, cond-mat/9908263 (1999)]. The overall agreement between theory and experiment is good, which on the one hand confirms that the experimental peaks indeed reflect the ring-like structure of the sample, and on the other hand, asseses the suitability of the theoretical method to describe such small nanostructures. The addition energies of one- and two-electron rings are also reported and compared with the corresponding capacitance spectra.

N. Rajewsky, T. Sasamoto, E. Speer

We study the stationary state of a simple exclusion process on a ring which was recently introduced by Arndt et al. (J. Phys. A 31 (1998) L45; J. Stat. Phys. 97 (1999) 1). This model exhibits spatial condensation of particles. It has been argued (J. Phys. A 31 (1998) L45; cond-mat/9809123) that the model has a phase transition from a “mixed phase” to a “disordered phase”. However, in this paper exact calculations are presented which, we believe, show that in the framework of a grand canonical ensemble there is no such phase transition. An analysis of the fluctuations in the particle density strongly suggests that the same result also holds for the canonical ensemble and suggests the existence of extremely long (but finite) correlation lengths (for example 1070 sites) in the infinite system at moderate parameter values in the mixed regime.

Gerardo Rodríguez Ortíz, J. Dukelsky

5 pages, 1 table, 4 figures.--PACS nrs.: 03.75.Ss, 02.30.Ik, 05.30.Fk, 74.20.Fg.--Arxiv pre-print available at: http://arxiv.org/abs/cond-mat/0503664

Xudong Zhao, G. Yu, Y. Cho et al.

This paper is published in Advanced Materials (available at this http URL). It has been withdrawn from the cond-mat preprint archive in order to avoid a violation of the Journal's policy.