We argue from both technical and physical points of view that the main result shown in the Comment [arXiv:0709.2619] by Cherrolet et al. [Phys. Rev. B 80, 037101 (2009)] as well as the authors' interpretations of the result are not sufficient to draw the conclusion that the scaling law at the mobility edge takes the form T \propto 1/L^2. On the other hand, we believe that the result shows some evidence of T \propto ln L/L^2 behavior found in S. K. Cheung and Z. Q. Zhang, Phys. Rev. B 72, 235102 (2005) [arXiv:cond-mat/0509381]. More calculations with even larger L's are necessary to give a more definitive answer to this question.
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.
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.
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.
Motivated by recent scanning tuneling microscopy (STM) experiments on Bi 2 Sr 2 CaCu 2 O 8 + δ [J. E. Hoffman et al., Science 295, 466 (2002); C. Howald et al., cond-mat/0201546 (unpublished); J. E. Hoffman et al., Science 297, 1149 (2002): K. McElroy et al. (unpublished); C. Howald et al., cond-mat/0208442 (unpublished)], we study the effects of weak translational symmetry breaking on the quasiparticle spectrum of a d-wave superconductor. We develop a general formalism to discuss periodic charge order, as well as quasiparticle scattering off localized defects. We argue that the STM experiments in Bi 2 Sr 2 CaCu 2 O 8 + δ cannot be explained using a simple charge density wave order parameter, but are consistent with the presence of a periodic modulation in the electron hopping or pairing amplitude. We review the effects of randomness and pinning of the charge order and compare it to the impurity scattering of quasiparticles. We also discuss implications of weak translational symmetry breaking for angle resolved photoemission spectroscopy experiments.
The excitation spectrum of an $S=1∕2$ two-dimensional triangular quantum antiferromagnet is studied using $1∕S$ expansion. Due to the noncollinearity of the classical ground state significant and nontrivial corrections to the spin-wave spectrum appear already in the first order in $1∕S$ in contrast to the square lattice antiferromagnet. The resulting magnon dispersion is almost flat in a substantial portion of the Brillouin zone. Our results are in quantitative agreement with recent series expansion studies by Zheng et al. [Phys. Rev. Lett. 96, 057201 (2006); cond-mat/0608008 (unpublished)].
AIDS is the pandemic of our era. A disease that scares us not only because it is fatal but also because its insidious time course makes us all potential carriers long before it hands us our heads in a basket. The strange three stage dynamics of aids is also one of the major puzzles while describing the disease theoretically (Pantaleo et al., N. Engl. J. Med. 328 (1993) 327). Aids starts, like most diseases, in a peak of virus expression [R.M. Zorzenon dos Santos, Immune responses: Getting close to experimental results with cellular automata models, in: D. Stauffer (Ed.), Annual Review of Computational Physics VI, 1999, pp. 159–202; R.M. Zorzenon dos Santos, S.C. Coutinho, On the dynamics of the evolution of HIV infection, cond-mat/0008081], which is practically wiped out by the immune system. However it then remains in the body at a low level of expression until later (some time years later) when there is an outbreak of the disease which terminally cripples the immune system causing death from various common pathogens. In this paper we show, using a microscopic simulation, that the time course of AIDS is determined by the interactions of the virus and the immune cells in the shape space of antigens and that it is the virus's ability to move more rapidly in this space (its high mutability) that causes the time course and eventual “victory” of the disease. These results open the way for further experimental and therapeutic conclusions in the ongoing battle with the HIV epidemic.
We construct a trajectory-based semiclassical theory of shot noise in clean chaotic cavities. In the universal regime of vanishing Ehrenfest time tau(E), we reproduce the random matrix theory result and show that the Fano factor is exponentially suppressed as tau(E) increases. We demonstrate how our theory preserves the unitarity of the scattering matrix even in the regime of finite tau(E). We discuss the range of validity of our semiclassical approach and point out subtleties relevant to the recent semiclassical treatment of shot noise in the universal regime by Braun et al. (cond-mat/0511292).
A recent paper [Burovski et al., cond-mat/0507352] reports on a new, high-accuracy simulation of the classical phi^4 model (in the three-dimensional XY universality class). The authors claim that a careful scaling analysis of their data gives nu = 0.6711(1) for the thermal critical exponent. If correct, this would neatly resolve the discrepancy between numerical simulations and experiments on 4He. There is reason, however, to doubt the accuracy of the result. A re-analysis of the data yields a significantly higher value of nu, one that is consistent with other Monte Carlo studies.
Following findings by Ormerod and Mounfield (Physica A 293 (2001) 573) Wright (The duration of recessions follows an exponential nota power law, cond-mat/0311585) rises the problem whether a power (Ormerod and Mounfield, 2001) or an exponential law (Wright) describes the distribution of occurrences of economic recession periods. In order to clarify the controversy a different set of GDP data are hereby examined. The conclusion about a power law distribution of recession periods seems better though the matter is not entirely settled. The case of prosperity duration is also studied and is found to follow a power law. Universal but also non universal features between recession and prosperity cases are emphasized. Considering that the economy is basically a bistable (recession/prosperity) system we may derive a characteristic (de)stabilisation time. 89.65.Gh; 05.45.Tp; 02.70.Rv Econophysics; Time series analysis; Power law; Exponential law; Recession; Prosperity
We study the spin Hall effect taking into account the impurity scattering effect as general as possible with the focus on the definition of the spin current. The conserved bulk spin current (Zhang et al., cond-mat/0503505) satisfying the continuity equation of spin is considered in addition to the conventional one defined by the symmetric product of the spin and velocity operators. Conditions for nonzero spin Hall current are clarified. In particular, it is found that (i) the spin Hall current is nonzero in the Rashba model with a finite-range impurity potential, and (ii) the spin Hall current vanishes in the cubic Rashba model with a $\ensuremath{\delta}$-function impurity potential.
This paper is withdrawn. While almost all findings reported here remain valid, some of our comments on the fate of weak localization corrections to the conductance in the deep semiclassical limit are now obsolete. Contrarily to what was suggested here, we find an exponential suppression of weak localization at finite Ehrenfest time. For more details, see cond-mat/0512662 .
In this paper we study analytically a simple one-dimensional model of mass transport. We introduce a parameter p that interpolates between continuous-time dynamics (p→0 limit) and discrete parallel update dynamics (p=1). For each p, we study the model with (i) both continuous and discrete masses and (ii) both symmetric and asymmetric transport of masses. In the asymmetric continuous mass model, the two limits p=1 and p→0 reduce respectively to the q-model of force fluctuations in bead packs [S. N. Coppersmith et al., Phys. Rev. E53:4673 (1996)] and the recently studied asymmetric random average process [J. Krug and J. Garcia, cond-mat/9909034]. We calculate the steady-state mass distribution function P(m) assuming product measure and show that it has an algebraic tail for small m, P(m)∼m−β, where the exponent β depends continuously on p. For the asymmetric case we find β(p)=(1−p)/(2−p) for 0≤p<1 and β(1)=−1, and for the symmetric case, β(p)=(2−p)2/(8−5p+p2) for all 0≤p≤1. We discuss the conditions under which the product measure ansatz is exact. We also calculate exactly the steady-state mass–mass correlation function and show that while it decouples in the asymmetric model, in the symmetric case it has a nontrivial spatial oscillation with an amplitude decaying exponentially with distance.