Coupling nanomechanical cantilevers to dipolar molecules

We investigate the coupling of a nanomechanical oscillator in the quantum regime with molecular (electric) dipoles. We find theoretically that the cantilever can produce single-mode squeezing of the center-of-mass motion of an isolated trapped molecule and two-mode squeezing of the phonons of an array of molecules. This work opens up the possibility of manipulating dipolar crystals, which have been recently proposed as quantum memory, and more generally, is indicative of the promise of nanoscale cantilevers for the quantum detection and control of atomic and molecular systems.Comment: 3 figures, 4page

The Large Magellanic Cloud: A power spectral analysis of Spitzer images

We present a power spectral analysis of Spitzer images of the Large Magellanic Cloud. The power spectra of the FIR emission show two different power laws. At larger scales (kpc) the slope is ~ -1.6, while at smaller ones (tens to few hundreds of parsecs) the slope is steeper, with a value ~ -2.9. The break occurs at a scale around 100-200 pc. We interpret this break as the scale height of the dust disk of the LMC. We perform high resolution simulations with and without stellar feedback. Our AMR hydrodynamic simulations of model galaxies using the LMC mass and rotation curve, confirm that they have similar two-component power-laws for projected density and that the break does indeed occur at the disk thickness. Power spectral analysis of velocities betrays a single power law for in-plane components. The vertical component of the velocity shows a flat behavior for large structures and a power law similar to the in-plane velocities at small scales. The motions are highly anisotropic at large scales, with in-plane velocities being much more important than vertical ones. In contrast, at small scales, the motions become more isotropic.Comment: 8 pages, 4 figures, talk presented at "Galaxies and their Masks", celebrating Ken Freeman's 70-th birthday, Sossusvlei, Namibia, April 2010. To be published by Springer, New York, editors D.L. Block, K.C. Freeman, & I. Puerar

Universal Scaling Property of System Approaching Equilibrium

In this Letter we show that the diffusion kinetics of kinetic energy among the atoms in non- equilibrium crystalline systems follows universal scaling relation and obey Levy-walk properties. This scaling relation is found to be valid for systems no matter how far they are driven out of equilibrium.Comment: 6 pages, 4 figure

Signature of strong atom-cavity interaction on critical coupling

We study a critically coupled cavity doped with resonant atoms with metamaterial slabs as mirrors. We show how resonant atom-cavity interaction can lead to a splitting of the critical coupling dip. The results are explained in terms of the frequency and lifetime splitting of the coupled system.Comment: 8 pages, 5 figure

Aspects of Horava-Lifshitz cosmology

We review some general aspects of Horava-Lifshitz cosmology. Formulating it in its basic version, we extract the cosmological equations and we use observational data in order to constrain the parameters of the theory. Through a phase-space analysis we extract the late-time stable solutions, and we show that eternal expansion, and bouncing and cyclic behavior can arise naturally. Concerning the effective dark energy sector we show that it can describe the phantom phase without the use of a phantom field. However, performing a detailed perturbation analysis, we see that Horava-Lifshitz gravity in its basic version suffers from instabilities. Therefore, suitable generalizations are required in order for this novel theory to be a candidate for the description of nature.Comment: 10 pages, 4 figures, invited talk given at the 2nd International Workshop on Dark Matter, Dark Energy and Matter-Antimatter Assymetry, National Tsing Hua University, Hsinchu, Taiwan, November 5-6, 201

Ab initio explanation of disorder and off-stoichiometry in Fe-Mn-Al-C kappa carbides

Carbides play a central role for the strength and ductility in many materials. Simulating the impact of these precipitates on the mechanical performance requires the knowledge about their atomic configuration. In particular, the C content is often observed to substantially deviate from the ideal stoichiometric composition. In the present work, we focus on Fe-Mn-Al-C steels, for which we determined the composition of the nano-sized kappa carbides (Fe,Mn)3AlC by atom probe tomography (APT) in comparison to larger precipitates located in grain boundaries. Combining density functional theory with thermodynamic concepts, we first determine the critical temperatures for the presence of chemical and magentic disorder in these carbides. Secondly, the experimentally observed reduction of the C content is explained as a compromise between the gain in chemical energy during partitioning and the elastic strains emerging in coherent microstructures