Physical Review Letters

Toninelli, C; Biroli, G; Fisher, D. S

doi: 10.1103/PhysRevLett.98.129602pmid: N/A

A Reply to the Comment by M. Jeng and J. M. Schwarz.

Brodin, G; Marklund, M; Eliasson, B; Shukla, P. K

doi: 10.1103/PhysRevLett.98.125001pmid: 17501131

We present for the first time the nonlinear dynamics of quantum electrodynamic (QED) photon splitting in a strongly magnetized electron-positron (pair) plasma. By using a QED corrected Maxwell equation, we derive a set of equations that exhibit nonlinear couplings between electromagnetic (EM) waves due to nonlinear plasma currents and QED polarization and magnetization effects. Numerical analyses of our coupled nonlinear EM wave equations reveal the possibility of a more efficient decay channel, as well as new features of energy exchange among the three EM modes that are nonlinearly interacting in magnetized pair plasmas. Possible applications of our investigation to astrophysical settings, such as magnetars, are pointed out.

Abulencia, A; Adelman, J; Affolder, T; Akimoto, T; Albrow, M. G; Ambrose, D. G; Amerio, S. G; Amidei, D. G; Anastassov, A. G; Anikeev, K. G; Annovi, A. G; Antos, J. G; Aoki, M. G; Apollinari, G. G; Arguin, J.-F. G; Arisawa, T. G;

Şen, Cengiz ; Alvarez, Gonzalo ; Dagotto, Elbio

doi: 10.1103/PhysRevLett.98.127202pmid: 17501153

The one-orbital model for manganites with cooperative phonons and superexchange coupling J AF is in<?format ?>vestigated via large-scale Monte Carlo simulations. The results for two orbitals are also briefly discussed. Focusing on the electron density n = 0.75 , a regime of competition between ferromagnetic metallic and charge-ordered (CO) insulating states is identified. In the vicinity of the associated bicritical point, colossal magnetoresistance (CMR) effects are observed. The CMR is associated with the development of short-distance correlations among polarons, above the spin ordering temperatures, resembling the charge arrangement of the low-temperature CO state.

Gorshkov, Alexey V; André, Axel V; Fleischhauer, Michael V; Sørensen, Anders S; Lukin, Mikhail D

doi: 10.1103/PhysRevLett.98.123601pmid: 17501121

We present a universal physical picture for describing storage and retrieval of photon wave packets in a Λ -type atomic medium. This physical picture encompasses a variety of different approaches to pulse storage ranging from adiabatic reduction of the photon group velocity and pulse-propagation control via off-resonant Raman fields to photon-echo-based techniques. Furthermore, we derive an optimal control strategy for storage and retrieval of a photon wave packet of any given shape. All these approaches, when optimized, yield identical maximum efficiencies, which only depend on the optical depth of the medium.

Kunz, Martin ; Sapone, Domenico

doi: 10.1103/PhysRevLett.98.121301pmid: 17501110

There is now strong observational evidence that the expansion of the Universe is accelerating. The standard explanation invokes an unknown “dark energy” component. But such scenarios are faced with serious theoretical problems, which has led to increased interest in models where instead general relativity is modified in a way that leads to the observed accelerated expansion. The question then arises whether the two scenarios can be distinguished. Here we show that this may not be so easy, demonstrating explicitly that a generalized dark energy model can match the growth rate of the Dvali-Gabadadze-Porrati model and reproduce the 3 + 1 dimensional metric perturbations. Cosmological observations are then unable to distinguish the two cases.

Sen, Sudeepto ; Xie, Yuping ; Kumar, Sanat K

doi: 10.1103/PhysRevLett.98.128302pmid: 17501164

Small angle neutron scattering studies on polystyrene loaded with spherical silica nanoparticles under contrast-matched conditions unequivocally show that chain conformations follow unperturbed Gaussian statistics independent of chain molecular weight and filler composition. Liquid state theory calculations are consistent with this conclusion and also predict filler-induced modification of interchain polymer correlations which have a distinctive scattering signature that is in nearly quantitative agreement with our observations.

Billangeon, P.-M; Pierre, F; Bouchiat, H; Deblock, R

doi: 10.1103/PhysRevLett.98.126802pmid: 17501148

A single-Cooper-pair transistor (SCPT) is coupled capacitively to a voltage biased Josephson junction, used as a high-frequency generator. Thanks to the high energy of photons generated by the Josephson junction, transitions between energy levels, not limited to the first two levels, were induced and the effect of this irradiation on the dc Josephson current of the SCPT was measured. The phase and gate bias dependence of energy levels of the SCPT at high energy is probed. Because the energies of photons can be higher than the superconducting gap we can induce not only transfer of Cooper pairs but also transfer of quasiparticles through the island of the SCPT, thus controlling the poisoning of the SCPT. This can both decrease and increase the average Josephson energy of the SCPT: its supercurrent is then controlled by high-frequency irradiation.

Artola, Pierre-Arnaud

doi: 10.1103/PhysRevLett.98.125901pmid: 17501137

In a recent Letter by Köhler Phys. Rev. Lett. 87 , 055901 ( 2001 ) PRLTAO 0031-9007 10.1103/PhysRevLett.87.055901 , it has been shown that the Soret effect or thermal diffusion can be split into three different contributions: mass, moment of inertia, and a so-called chemical effect, but only the chemical effect gives rise to a composition dependent contribution. As it is experimentally difficult to deal with the chemical contribution without changing the two others, it has not been studied accurately yet. Our Letter presents both equilibrium and nonequilibrium Molecular Dynamics in simple Lennard-Jones mixtures. By thoroughly changing the strength of direct and cross interaction energies between particles, we show that the composition dependence and the change of sign of the Soret coefficient is driven only by the nature of interactions between unlike particles and propose a microscopic interpretation of the Soret effect.

Brilliantov, N. V; Pöschel, T. V; Kranz, W. T; Zippelius, A. T

doi: 10.1103/PhysRevLett.98.128001pmid: 17501156

In a granular gas of rough particles the axis of rotation is shown to be correlated with the translational velocity of the particles. The average relative orientation of angular and linear velocities depends on the parameters which characterize the dissipative nature of the collision. We derive a simple theory for these correlations and validate it with numerical simulations for a wide range of coefficients of normal and tangential restitution. The limit of smooth spheres is shown to be singular: even an arbitrarily small roughness of the particles gives rise to orientational correlations.