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Weak-Localization-Like Temperature-Dependent Conductivity of a Dilute Two-Dimensional Hole Gas in a Parallel Magnetic Field

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Physical Review Letters 2002年第1期89卷 016801-016801页

作者： Xuan P. A. Gao Allen P. Mills, Jr. Arthur P. Ramirez Loren N. Pfeiffer Kenneth W. West Department of Applied Physics & Applied Math Columbia University New York City New York 10027 Department of Physics University of California Riverside California 92521 Los Alamos National Laboratory Los Alamos New Mexico 87545 Bell Laboratories Lucent Technologies Murray Hill New Jersey 07974

We have studied the magnetotransport properties of a high mobility two-dimensional hole gas (2DHG) in a 10 nm GaAs quantum well with densities in the range of (0.7–1.6)×1010cm−2 on the metallic side of the zero-field “metal-insulator transition.” In a parallel field well above Bc that suppresses the metallic conductivity, the 2DHG exhibits a conductivity Δg(T)≈(1/π)(e2/h)lnT reminiscent of weak localization for Fermi liquids. The experiments are consistent with the coexistence of two phases in our system: a metallic phase and a weakly insulating Fermi liquid phase.

关键词： Semiconductor quantum wells

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Conductivity of infinite-layer NdNiO2 as a probe of spectator bands

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Physical Review B 2023年第20期107卷 205155-205155页

作者： Harrison LaBollita Alexander Hampel Jonathan Karp Antia S. Botana Andrew J. Millis Department of Physics Arizona State University Tempe Arizona 85287 USA Center for Computational Quantum Physics Flatiron Institute 162 5th Avenue New York New York 10010 USA Department of Applied Physics and Applied Math Columbia University New York New York 10027 USA Department of Physics Columbia University New York New York 10027 USA

Using a density functional theory (DFT) plus dynamical mean-field theory methodology, we compute the many-body electronic structure and optical conductivity of NdNiO2 under the influence of large scattering rates on the Nd(5d) bands and including dynamical interactions on the Nd(5d) orbitals with shifts of the Nd-Ni d-level energy difference. We find a robust conducting pathway in the out-of-plane direction arising from strong hybridization between the Ni-dz2 and Nd(5d) orbitals. This pathway can be “short-circuited” if this hybridization is suppressed through large electronic scattering rates but is not reduced to zero even by very large beyond-DFT shifts of the Nd-Ni d-level energy splitting. The computed in-plane conductivity for NdNiO2 predicts the material to be a “good metal” in contrast to experiments indicating the material is a “bad metal” or “weak insulator”. Our results motivate future experiments measuring the c-axis resistivity as a proxy for the spectator bands and suggests the essential difference between the infinite-layer nickelates and the cuprates is dimensionality of their electronic structures.

关键词： Optical conductivity Strongly correlated systems Unconventional superconductors Density functional theory Dynamical mean field theory

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Oscillations and waves near the limb from trace UV observations

Oscillations and waves near the limb from trace UV observati...

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Proceedings of the Magnetic Coupling of the solar Atmosphere Euroconference and IAU Colloquium 188

作者： Alissandrakis, C.E. Zachariadis, Th.G. Gontikakis, C. Section of Astro-Geophysics Department of Physics University of Ioannina GR-45110 Ioannina Greece Res. Ctr. Astron. and Applied Math. Academy of Athens 14 Anagnostopoulou St. GR-10673 Athens Greece

We analyze TRACE observations near the limb in the 1550, 1600 and 1700 A UV bands. Intensity-time images were computed at various distances from the limb. Two dimensional Fourier analysis on the ω-κ plane shows very well the well-known p-mode ridges which persist up to the limb in all three bands. Their power decreases almost proportionally to the cosine of the heliocentric angle at 1600 and 1700 A, being more flat in the Civ 1550 Å band.

关键词： Space research

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Two-Dimensional Metal in a Parallel Magnetic Field

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Physical Review Letters 2002年第16期88卷 166803-166803页

作者： Xuan P. A. Gao Allen P. Mills, Jr. Arthur P. Ramirez Loren N. Pfeiffer Kenneth W. West Bell Laboratories Lucent Technologies Murray Hill New Jersey 07974 Department of Applied Physics & Applied Math Columbia University New York City New York 10027 Los Alamos National Laboratory Los Alamos New Mexico 87545

We have investigated the effect of an in-plane parallel magnetic field (B‖) on two high mobility metalliclike dilute two-dimensional hole gas systems in GaAs quantum wells. The experiments reveal that, while suppressing the magnitude of the low temperature resistance drop, B‖ does not affect Ea, the characteristic energy scale of the metallic resistance drop. The field Bc at which the metalliclike resistance drop vanishes is dependent on both the width of the quantum well and the orientation of B‖. It is unexpected that Ea is unaffected by B‖ up to Bc despite the fact that the Zeeman energy at Bc is roughly equal to Ea.

关键词： Electron gas

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Local measurement strategies for multipartite entanglement quantification

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Physical Review A 2024年第1期110卷 012454-012454页

作者： Luke Coffman Akshay Seshadri Graeme Smith Jacob L. Beckey Department of Physics JILA NIST and Institute for Quantum Computing and Department of Applied Math University of Waterloo Waterloo Ontario Canada N2L 3G1

Despite multipartite entanglement being a global property of a quantum state, a number of recent works have made it clear that it can be quantified using only local measurements. This is appealing because local measurements are the easiest to implement on current quantum hardware. However, it remains an open question what protocol one should use in order to minimize the resources required to estimate multipartite entanglement from local measurements alone. In this work, we construct and compare several estimators of multipartite entanglement based solely on the data from local measurements. We first construct statistical estimators for a broad family of entanglement measures using local randomized measurement (LRM) data before providing a general criterion for the construction of such estimators in terms of projective 2-designs. Importantly, this allows us to derandomize the multipartite estimation protocol based on LRMs. In particular, we show how local symmetric, informationally complete positive operator-valued measures enable multipartite entanglement quantification with only a single measurement setting. For all estimators, we provide both the classical postprocessing cost and rigorous performance guarantees in the form of analytical upper bounds on the number of measurements needed to estimate the measures to any desired precision.

关键词： Entanglement measures Quantum entanglement Quantum information theory

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Preparation of BaTiO3/CoFe2O4 periodicity magnetoelectric composites multilayer thin films and study in magnetoelectricity properties

Preparation of BaTiO3/CoFe2O4 periodicity magnetoelectric co...

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中国化学会第五届全国结构化学学术会议

作者： Tian Xia-Xia Qu Shao-Bo Pei Zhi-Bing Department of Applied Math and Physics Air Force Engineering University College of ScienceXianShanxi710051china

BaTiO3 and CoFe2 04 precursor solution were prepared by sol-gel *** magnetoelectric thin films were prepared on Si *** structure and morphology of the products were examined by means of X-ray diffraction and scanning electron microscope,the effect on their properties of temperatures were *** properties were measured by means of vibrating sample magnetometer and a direct current *** show that these films gained integrated crystal and periodicity coupling films,the periodicity films exhibit good ferroelectrics and magnetic properties,such as higher dieletric constant,high saturation magnetization,low *** composites also demonstrated a magnetoelectric effect.

关键词： BaTiO3/CoFe2O4 composites thin films Periodicity magnetoelectric

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Soft vibrations and acoustic-optic mode couplings in ferroelectrics with large piezoelectric responses

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Physical Review B 2002年第6期66卷 064110-064110页

作者： Irene Dujovne Tae-Yeong Koo A. Pinczuk Sang-Wook Cheong B. S. Dennis Department of Applied Physics and Applied Math Columbia University New York New York 10027 Bell Labs Lucent Technologies Murray Hill New Jersey 07974 Department of Physics and Astronomy Rutgers University Piscataway New Jersey 08855 Department of Physics Columbia University New York New York 10027

Raman spectra of Pb[(Mg1/3Nb2/3)1−x,Tix]O3 and Pb[(Zn1/3Nb2/3)1−x,Tix]O3 solid solutions display transverse optic vibration modes that soften with composition and reveal interactions between acoustic and optic modes with enhanced low frequency responses at compositions close to the tetragonal-rhombohedral phase boundaries. The results suggest that intrinsic microscopic interactions may coexist with effects characteristic of disordered ferroelectrics in creating the giant piezoelectric responses of these materials.

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Prediction of the Hitec Molten Salt Convective Heat Transfer Performance Using Artificial Neural Networks 1st

Prediction of the Hitec Molten Salt Convective Heat Transfer...

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1st International Conference on Artificial Intelligence and Computer Visions, AICV 2020

作者： ElShafei, Ahmed Ibrahim Sallam, Omar Khaled Boraey, Mohammed A. Guaily, Amr Nile University Giza12588 Egypt School of Engineering and Applied Sciences Nile University Giza12588 Egypt Mechanical Power Engineering Department Zagazig University Zagazig44519 Egypt Department of Engineering Math and Physics Faculty of Engineering Cairo University Giza12613 Egypt

ISBN: (纸本)9783030442880

Hitec molten salt is a ternary eutectic mixture salt that is used as an energy storage medium in concentrated solar power plants to improve the system performance and reduce the operational cost. Thus, the heat transfer performance represented in Nusselt number has been investigated numerically under different inlet temperature and velocity conditions with constant uniform side heat flux. Also, friction factor and mass flow rate are studied numerically. CFD input/output data with 40 studied cases are used as a training dataset of a 2-layer Neural Network for thermo-hydro fields’ accelerated results predictions. Bayesian regularized Neural Network showed a satisfactory agreement for thermo-hydro fields’ predictions compared to the CFD results for the testing dataset not included in the training of the network. © 2020, Springer Nature Switzerland AG.

关键词： Solar energy

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Cosmological test using the high-redshift detection rate of FSRQs with the square kilometer array

arXiv

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arXiv 2019年

作者： Leaf, Kyle Melia, Fulvio Department of Physics University of Arizona AZ85721 United States Applied Math Program Department of Physics University of Arizona AZ85721 United States

We present a phenomenological method for predicting the number of Flat Spectrum Radio Quasars (FSRQs) that should be detected by upcoming Square Kilometer Array (SKA) SKA1-MID Wide Band 1 and Medium-Deep band 2 surveys. We use the Fermi Blazar Sequence and mass estimates of Fermi FSRQs, and gamma-ray emitting Narrow Line Seyfert 1 galaxies, to model the radio emission of FSRQs as a function of mass alone, assuming a near-Eddington accretion rate, which is suggested by current quasar surveys at z > 6. This is used to determine the smallest visible black hole mass as a function of redshift in two competing cosmologies we compare in this paper: The standard LCDM model and the R_h=ct universe. We then apply lockstep growth to the observed black-hole mass function at z=6 in order to devolve that population to higher redshifts and determine the number of FSRQs detectable by the SKA surveys as a function of z. We find that at the redshifts for which this method is most valid, LCDM predicts ~30 times more FSRQs than R_h=ct for the Wide survey, and ~100 times more in the Medium-Deep survey. These stark differences will allow the SKA surveys to strongly differentiate between these two models, possibly rejecting one in comparison with the other at a high level of confidence. Copyright © 2019, The Authors. All rights reserved.

关键词： Cosmology

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On the parameters influencing the deposition of polystyrene colloidal crystals

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Materials Science and Engineering C 2008年第7期28卷 1038-1043页

作者： Yoldi, María Arcos, Cristina Paulke, Bernd-R. Sirera, Rafael González-Viñas, Wenceslao Görnitz, Eckhard Institute for Applied Polymer Research Geiselbergstr. 69 D-14476 Potsdam-Golm Germany Complex Systems Group. Department of Physics and Appl. Math. University of Navarra Irunlarrea s/n E-31080 Pamplona Spain Depatment of Chemistry and Soil Sci. University of Navarra Irunlarrea s/n E-31080 Pamplona Spain

Colloidal crystals of polystyrene particles of 1.0, 1.4 and 2.8μm diameter have been prepared by vertical deposition. The influence of parameters such as temperature, particle size and concentration as well as dispersion medium has been studied. The size of domain and the crystalline structure of the particle arrays have been analyzed by optical microscopy. The quality of the crystals has been improved (minimizing cracks) by controlling sedimentation (density matching), evaporation (volatility of the medium) and drying (co-solvents). © 2007 Elsevier B.V. All rights reserved.

关键词： Cracks

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