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Full-Text Articles in Physics
Wave-Function Functionals For The Density, Marlina Slamet, Xiao-Yin Pan, Viraht Sahni
Wave-Function Functionals For The Density, Marlina Slamet, Xiao-Yin Pan, Viraht Sahni
Publications and Research
We extend the idea of the constrained-search variational method for the construction of wave-function functionals psi[chi] of functions chi. The search is constrained to those functions chi such that psi[chi] reproduces the density rho(r) while simultaneously leading to an upper bound to the energy. The functionals are thereby normalized and automatically satisfy the electron-nucleus coalescence condition. The functionals psi[chi] are also constructed to satisfy the electron-electron coalescence condition. The method is applied to the ground state of the helium atom to construct functionals psi[chi] that reproduce the density as given by the Kinoshita correlated wave function. The expectation of single-particle …
Graded Index And Randomly Oriented Core-Shell Silicon Nanowires With Broadband And Wide Angle Antireflection, P. Pignalosa, H. Lee, L. Qiao, M. Tseng, Y. Yi
Graded Index And Randomly Oriented Core-Shell Silicon Nanowires With Broadband And Wide Angle Antireflection, P. Pignalosa, H. Lee, L. Qiao, M. Tseng, Y. Yi
Publications and Research
Antireflection with broadband and wide angle properties is important for a wide range of applications on photovoltaic cells and display. The SiOx shell layer provides a natural antireflection from air to the Si core absorption layer. In this work, we have demonstrated the random core-shell silicon nanowires with both broadband (from 400nm to 900nm) and wide angle (from normal incidence to 60o) antireflection characteristics within AM1.5 solar spectrum. The graded index structure from the randomly oriented core-shell (Air/SiOx/Si) nanowires may provide a potential avenue to realize a broadband and wide angle antireflection layer
Climate Change: The Fork At The End Of Now, Micha Tomkiewicz
Climate Change: The Fork At The End Of Now, Micha Tomkiewicz
Publications and Research
There are many books on global warming written entirely from a layman's perspective, and there is a great deal of scientific literature on this subject. But few if any books attempt to bridge the science to those who lack a rigorous background in mathematics, physics and chemistry-but who may be working on careers in environmental science and policy. The new text is designed to introduce the field of global climate change from a scientific perspective-but written in a way that is accessible to students with some or little science background. It reviews the basic principles of climatic thermodynamics and atmospheric …
A Bulk Inflaton From Large-Volume Extra Dimensions, Brian Greene, Daniel N. Kabat, Janna Levin, Dylan Thurston
A Bulk Inflaton From Large-Volume Extra Dimensions, Brian Greene, Daniel N. Kabat, Janna Levin, Dylan Thurston
Publications and Research
The universe may have extra spatial dimensions with large volume that we cannot perceive because the energy required to excite modes in the extra directions is too high. Many examples are known of such manifolds with a large volume and a large mass gap. These compactifications can help explain the weakness of four-dimensional gravity and, as we show here, they also have the capacity to produce reasonable potentials for an inflaton field. Modeling the inflaton as a bulk scalar field, it becomes very weakly coupled in four dimensions, and this enables us to build phenomenologically acceptable inflationary models with tunings …
Differential Microlensing Measurements Of Quasar Broad-Line Kinematics In Q2237+0305, Matthew J. O'Dowd, N F. Bate, R L. Webster, R Wayth
Differential Microlensing Measurements Of Quasar Broad-Line Kinematics In Q2237+0305, Matthew J. O'Dowd, N F. Bate, R L. Webster, R Wayth
Publications and Research
The detailed workings of the central engines of powerful quasars remain a mystery. This is primarily due to the fact that, at their cosmological distances, the inner regions of these quasars are spatially unresolvable. Reverberation mapping is now beginning to unlock the physics of the Broad Emission Line Region (BELR) in nearby, low-luminosity quasars, however it is still unknown whether this gas is dominated by virial motion, by outflows, or infall. The challenge is greater for more distant, powerful sources due to the very long response time of the BELR to changes in the continuum. We present a new technique …
Physics Professor Leads Research Into Laser Uses, Aldemaro Romero Jr.
Physics Professor Leads Research Into Laser Uses, Aldemaro Romero Jr.
Publications and Research
No abstract provided.
Quantum Entanglement Of A Tunneling Spin With Mechanical Modes Of A Torsional Resonator, Dmitry A. Garanin, Eugene M. Chudnovsky
Quantum Entanglement Of A Tunneling Spin With Mechanical Modes Of A Torsional Resonator, Dmitry A. Garanin, Eugene M. Chudnovsky
Publications and Research
We solve Schr\"odinger equation describing a tunneling macrospin coupled to a torsional oscillator. Energy spectrum is studied for various quantum regimes. Magnetic susceptibility and noise spectrum are computed. We show that entanglement of the spin with mechanical modes of a subnanometer oscillator results in the decoherence of spin tunneling. For larger oscillators the presence of a tunneling spin can be detected through splitting of the mechanical mode at the resonance. Our results apply to experiments with magnetic molecules coupled to nanoresonators.
Quantum Tunneling Of The Interfaces Between Normal-Metal And Superconducting Regions Of A Type-I Pb Superconductor, Eugene M. Chudnovsky, S Velez, A Garcia-Santiago, J A. Hernandez
Quantum Tunneling Of The Interfaces Between Normal-Metal And Superconducting Regions Of A Type-I Pb Superconductor, Eugene M. Chudnovsky, S Velez, A Garcia-Santiago, J A. Hernandez
Publications and Research
Evidence of a non-thermal magnetic relaxation in the intermediate state of a type-I superconducor is presented. It is attributed to quantum tunneling of interfaces separating normal and superconducting regions. Tunneling barriers are estimated and temperature of the crossover from thermal to quantum regime is obtained from Caldeira-Leggett theory. Comparison between theory and experiment points to tunneling of interface segments of size comparable to the coherence length, by steps of order one nanometer.
Thermal Diffractive Corrections To Casimir Energies, Daniel N. Kabat, Dimitra Karabali
Thermal Diffractive Corrections To Casimir Energies, Daniel N. Kabat, Dimitra Karabali
Publications and Research
We study the interplay of thermal and diffractive effects in Casimir energies. We consider plates with edges, oriented either parallel or perpendicular to each other, as well as a single plate with a slit. We compute the Casimir energy at finite temperature using a formalism in which the diffractive effects are encoded in a lower dimensional non-local field theory that lives in the gap between the plates. The formalism allows for a clean separation between direct or geometric effects and diffractive effects, and makes an analytic derivation of the temperature dependence of the free energy possible. At low temperatures, with …
Ssgss: The Spitzer-Sdss-Galex Spectroscopic Survey, Matthew J. O'Dowd, David Schiminovich, Benjamin D. Johnson, Marie A. Treyer
Ssgss: The Spitzer-Sdss-Galex Spectroscopic Survey, Matthew J. O'Dowd, David Schiminovich, Benjamin D. Johnson, Marie A. Treyer
Publications and Research
The Spitzer-SDSS-GALEX Spectroscopic Survey (SSGSS) provides a new sample of 101 star-forming galaxies at z < 0.2 with unprecedented multi-wavelength coverage. New mid- to far-infrared spectroscopy from the Spitzer Space Telescope is added to a rich suite of previous imaging and spectroscopy, including ROSAT, Galaxy Evolution Explorer, Sloan Digital Sky Survey, Two Micron All Sky Survey, and Spitzer/SWIRE. Sample selection ensures an even coverage of the full range of normal galaxy properties, spanning two orders of magnitude in stellar mass, color, and dust attenuation. In this paper we present the SSGSS data set, describe the science drivers, and detail the sample selection, observations, data reduction, and quality assessment. Also in this paper, we compare the shape of the thermal continuum and the degree of silicate absorption of these typical, star-forming galaxies to those of starburst galaxies. We investigate the link between star formation rate, infrared luminosity, and total polycyclic aromatic hydrocarbon luminosity, with a view to calibrating the latter for spectral energy distribution models in photometric samples and at high redshift. Last, we take advantage of the 5-40 micron spectroscopic and far-infrared photometric coverage of this sample to perform detailed fitting of the Draine et al. dust models, and investigate the link between dust mass and star formation history and active galactic nucleus properties.
Dissipative Macroscopic Quantum Tunneling In Type-I Superconductors, Ricardo Zarzuela, Eugene M. Chudnovsky, Javier Tejada
Dissipative Macroscopic Quantum Tunneling In Type-I Superconductors, Ricardo Zarzuela, Eugene M. Chudnovsky, Javier Tejada
Publications and Research
We study macroscopic quantum tunneling of interfaces separating normal and superconducting regions in type-I superconductors. Mathematical model is developed, that describes dissipative quantum escape of a two-dimensional manifold from a planar potential well. It corresponds to, e.g., a current-driven quantum depinning of the interface from a grain boundary or from artificially manufactured pinning layer. Effective action is derived and instantons of the equations of motion are investigated. Crossover between thermal activation and quantum tunneling is studied and the crossover temperature is computed. Our results, together with recent observation of non-thermal low-temperature magnetic relaxation in lead, suggest possibility of a controlled …
Renormalization Of The Tunnel Splitting In A Rotating Nanomagnet, Michael F. O'Keeffe, Eugene M. Chudnovsky
Renormalization Of The Tunnel Splitting In A Rotating Nanomagnet, Michael F. O'Keeffe, Eugene M. Chudnovsky
Publications and Research
We study spin tunneling in a magnetic nanoparticle with biaxial anisotropy that is free to rotate about its anisotropy axis. Exact instanton of the coupled equations of motion is found that connects degenerate classical energy minima. We show that mechanical freedom of the particle renormalizes magnetic anisotropy and increases the tunnel splitting.
Constructing Local Bulk Observables In Interacting Ads/Cft, Daniel N. Kabat, Gilad Lifschytz, David A. Lowe
Constructing Local Bulk Observables In Interacting Ads/Cft, Daniel N. Kabat, Gilad Lifschytz, David A. Lowe
Publications and Research
Local operators in the bulk of AdS can be represented as smeared operators in the dual CFT. We show how to construct these bulk observables by requiring that the bulk operators commute at spacelike separation. This extends our previous work by taking interactions into account. Large-N factorization plays a key role in the construction. We show diagrammatically how this procedure is related to bulk Feynman diagrams.