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Articles 1 - 21 of 21
Full-Text Articles in Physics
Completely Top–Down Hierarchical Structure In Quantum Mechanics, Yakir Aharonov, Eliahu Cohen, Jeff Tollaksen
Completely Top–Down Hierarchical Structure In Quantum Mechanics, Yakir Aharonov, Eliahu Cohen, Jeff Tollaksen
Mathematics, Physics, and Computer Science Faculty Articles and Research
Can a large system be fully characterized using its subsystems via inductive reasoning? Is it possible to completely reduce the behavior of a complex system to the behavior of its simplest “atoms”? In this paper we answer these questions in the negative for a specific class of systems and measurements. After a general introduction of the topic, we present the main idea with a simple two-particle example, where strong correlations arise between two apparently empty boxes. This leads to surprising effects within atomic and electromagnetic systems. A general construction based on preand postselected ensembles is then suggested, wherein the Nbody …
Exploring The Neural Mechanisms Of Physics Learning, Jessica E. Bartley
Exploring The Neural Mechanisms Of Physics Learning, Jessica E. Bartley
FIU Electronic Theses and Dissertations
This dissertation presents a series of neuroimaging investigations and achievements that strive to deepen and broaden our understanding of human problem solving and physics learning. Neuroscience conceives of dynamic relationships between behavior, experience, and brain structure and function, but how neural changes enable human learning across classroom instruction remains an open question. At the same time, physics is a challenging area of study in which introductory students regularly struggle to achieve success across university instruction. Research and initiatives in neuroeducation promise a new understanding into the interactions between biology and education, including the neural mechanisms of learning and development. These …
Makerspace Club, Carolyn Brady
Makerspace Club, Carolyn Brady
Honors Expanded Learning Clubs
This is a unique club that allows children to explore the world around them and make projects using materials provided by educators, and to get children thinking about how things work in the world, and how they do. They gain knowledge about success and failure of these things by recreating them.
Spatial And Temporal Correlations Of Xy Macro Spins, Robert Streubel, Noah Kent, Scott Dhuey, Andreas Scholl, Steve Kevan, Peter Fischer
Spatial And Temporal Correlations Of Xy Macro Spins, Robert Streubel, Noah Kent, Scott Dhuey, Andreas Scholl, Steve Kevan, Peter Fischer
Robert Streubel Papers
We use nano disk arrays with square and honeycomb symmetry to investigate magnetic phases and spin correlations of XY dipolar systems at the micro scale. Utilizing magnetization sensitive X-ray photoemission electron microscopy, we probe magnetic ground states and the “order-by-disorder” phenomenon predicted 30 years ago. We observe the antiferromagnetic striped ground state in square lattices, and 6-fold symmetric structures, including trigonal vortex lattices and disordered floating vortices, in the honeycomb lattice. The spin frustration in the honeycomb lattice causes a phase transition from a long-range ordered locked phase over a floating phase with quasi long-range order and indications of a …
Large T1 Contrast Enhancement Using Superparamagnetic Nanoparticles In Ultra-Low Field Mri, Xiaolu Yin, Stephen E. Russek, Gary Zabow, Fan Sun, Jeotikatan Mohapatra, Kathryn E. Keenan, Michael A. Boss, Hao Zeng, J. Ping Liu, Alexandrea Viert, Sy-Hwang Liou, John Moreland
Large T1 Contrast Enhancement Using Superparamagnetic Nanoparticles In Ultra-Low Field Mri, Xiaolu Yin, Stephen E. Russek, Gary Zabow, Fan Sun, Jeotikatan Mohapatra, Kathryn E. Keenan, Michael A. Boss, Hao Zeng, J. Ping Liu, Alexandrea Viert, Sy-Hwang Liou, John Moreland
Nebraska Center for Materials and Nanoscience: Faculty Publications
Superparamagnetic iron oxide nanoparticles (SPIONs) are widely investigated and utilized as magnetic resonance imaging (MRI) contrast and therapy agents due to their large magnetic moments. Local field inhomogeneities caused by these high magnetic moments are used to generate T2 contrast in clinical high-field MRI, resulting in signal loss (darker contrast). Here we present strong T1 contrast enhancement (brighter contrast) from SPIONs (diameters from 11 nm to 22 nm) as observed in the ultra-low field (ULF) MRI at 0.13 mT. We have achieved a high longitudinal relaxivity for 18 nm SPION solutions, r1 = 615 s−1 mM−1, which is two …
Locality And Nonlocality In The Interaction-Free Measurement, Daniel Rohrlich, Yakir Aharonov, Tomer Landsberger
Locality And Nonlocality In The Interaction-Free Measurement, Daniel Rohrlich, Yakir Aharonov, Tomer Landsberger
Mathematics, Physics, and Computer Science Faculty Articles and Research
We present a paradox involving a particle and a mirror. They exchange a nonlocal quantity, modular angular momentum Lz mod 2ћ, but there seems to be no local interaction between them that allows such an exchange. We demonstrate that the particle and mirror do interact locally via a weak local current 〈Lz mod 2ћ〉w. In this sense, we transform the “interaction-free measurement” of Elitzur and Vaidman, in which two local quantities (the positions of a photon and a bomb in the two arms of a Mach-Zehnder interferometer) interact nonlocally, into a thought experiment in which two …
Fluctuating Hydrodynamics Of Reactive Liquid Mixtures, Changho Kim, Andy. Nonaka, John Bell, Alejandro Garcia, Aleksandar Donev
Fluctuating Hydrodynamics Of Reactive Liquid Mixtures, Changho Kim, Andy. Nonaka, John Bell, Alejandro Garcia, Aleksandar Donev
Faculty Publications
Fluctuating hydrodynamics (FHD) provides a framework for modeling microscopic fluctuations in a manner consistent with statistical mechanics and nonequilibrium thermodynamics. This paper presents an FHD formulation for isothermal reactive incompressible liquid mixtures with stochastic chemistry. Fluctuating multispecies mass diffusion is formulated using a Maxwell–Stefan description without assuming a dilute solution, and momentum dynamics is described by a stochastic Navier–Stokes equation for the fluid velocity. We consider a thermodynamically consistent generalization for the law of mass action for non-dilute mixtures and use it in the chemical master equation (CME) to model reactions as a Poisson process. The FHD approach provides remarkable …
Generalized Fock Spaces And The Stirling Numbers, Daniel Alpay, Motke Porat
Generalized Fock Spaces And The Stirling Numbers, Daniel Alpay, Motke Porat
Mathematics, Physics, and Computer Science Faculty Articles and Research
The Bargmann-Fock-Segal space plays an important role in mathematical physics and has been extended into a number of directions. In the present paper, we imbed this space into a Gelfand triple. The spaces forming the Fréchet part (i.e., the space of test functions) of the triple are characterized both in a geometric way and in terms of the adjoint of multiplication by the complex variable, using the Stirling numbers of the second kind. The dual of the space of test functions has a topological algebra structure, of the kind introduced and studied by the first named author and Salomon.
On Maxwell-Dirac Isomorphism, Florentin Smarandache, Victor Christianto
On Maxwell-Dirac Isomorphism, Florentin Smarandache, Victor Christianto
Branch Mathematics and Statistics Faculty and Staff Publications
No abstract provided.
Hartmann Characterization Of The Peem-3 Aberration-Corrected X-Ray Photoemission Electron Microscope, A. Scholl, M. A. Marcus, A. Doran, J. R. Nasiatka, A. T. Young, A. A. Macdowell, R. Streubel, N. Kent, J. Feng, W. Wan, H. A. Padmore
Hartmann Characterization Of The Peem-3 Aberration-Corrected X-Ray Photoemission Electron Microscope, A. Scholl, M. A. Marcus, A. Doran, J. R. Nasiatka, A. T. Young, A. A. Macdowell, R. Streubel, N. Kent, J. Feng, W. Wan, H. A. Padmore
Robert Streubel Papers
Aberration correction by an electron mirror dramatically improves the spatial resolution and transmission of photoemission electron microscopes. We will review the performance of the recently installed aberration corrector of the X-ray Photoemission Electron Microscope PEEM-3 and show a large improvement in the efficiency of the electron optics. Hartmann testing is introduced as a quantitative method to measure the geometrical aberrations of a cathode lens electron microscope. We find that aberration correction leads to an order of magnitude reduction of the spherical aberrations, suggesting that a spatial resolution of below 100 nm is possible at 100% transmission of the optics when …
Atmospheric Radiation And Tgfs: Unexplained Radiation In Our Skies, Adrian Gallegos
Atmospheric Radiation And Tgfs: Unexplained Radiation In Our Skies, Adrian Gallegos
Honors College Research
There is a significant correlation between atmospheric electrification via thunderstorms and the occurrence of large emissions of x-ray and gamma ray radiation known as Terrestrial Gamma Ray Flashes (TGFs). Some physical phenomenon may be explained by either the RREA or Thermal Runaway models, but the scientific community as a whole is still largely at work on the theoretical frameworks.
Weak Values From Strong Interactions In Neutron Interferometry, Tobias Denkmayr, Justin Dressel, Hermann Geppert-Kleinrath, Yuji Hasegawa, Stephan Sponar
Weak Values From Strong Interactions In Neutron Interferometry, Tobias Denkmayr, Justin Dressel, Hermann Geppert-Kleinrath, Yuji Hasegawa, Stephan Sponar
Mathematics, Physics, and Computer Science Faculty Articles and Research
In their original framework weak values must be measured by weak measurements that are minimally disturbing, meaning that the coupling between an investigated quantum system and a measurement device has no influence on the evolution of the system. However, under certain circumstances this weakness of the interaction is not necessary. In that case weak values can still be exactly determined from the statistics of the outcomes of arbitrary-strength generalized measurements. Here, we report an experimental procedure for neutron matter-waves that extends the notion of generalized eigenvalues for the neutron’s path system to allow the exact determination of weak values using …
Quasiprobability Behind The Out-Of-Time-Ordered Correlator, Nicole Yunger Halpern, Brian Swingle, Justin Dressel
Quasiprobability Behind The Out-Of-Time-Ordered Correlator, Nicole Yunger Halpern, Brian Swingle, Justin Dressel
Mathematics, Physics, and Computer Science Faculty Articles and Research
Two topics, evolving rapidly in separate fields, were combined recently: the out-of-time-ordered correlator (OTOC) signals quantum-information scrambling in many-body systems. The Kirkwood-Dirac (KD) quasiprobability represents operators in quantum optics. The OTOC was shown to equal a moment of a summed quasiprobability [Yunger Halpern, Phys. Rev. A 95, 012120 (2017)]. That quasiprobability, we argue, is an extension of the KD distribution. We explore the quasiprobability's structure from experimental, numerical, and theoretical perspectives. First, we simplify and analyze Yunger Halpern's weak-measurement and interference protocols for measuring the OTOC and its quasiprobability. We decrease, exponentially in system size, the number of trials …
Examining Students' Representation Choices In University Modeling Instruction, Daryl Mcpadden
Examining Students' Representation Choices In University Modeling Instruction, Daryl Mcpadden
FIU Electronic Theses and Dissertations
Representations (such as pictures, diagrams, word descriptions, equations, etc.) are critical tools for learning, problem solving, and communicating in science, particularly in physics where multiple representations often serve as intermediate steps, a means to evaluate a solution, and highlight different aspects a physical phenomenon. This dissertation explores the representation choices made by students in the University Modeling Instruction (MI) courses on problems from across introductory physics content. Modeling Instruction is a two-semester introductory, calculus-based physics sequence that was designed to guide students through the process of building, testing, applying, and refining models. As a part of this modeling cycle, students …
Thinking Out Loud On Early Creation Through The Lens Of Hermeneutics Of Sherlock Holmes (Towards A Model Of Universe Based On Turbulence-Generated Sound Theory), Victor Christianto, Florentin Smarandache
Thinking Out Loud On Early Creation Through The Lens Of Hermeneutics Of Sherlock Holmes (Towards A Model Of Universe Based On Turbulence-Generated Sound Theory), Victor Christianto, Florentin Smarandache
Branch Mathematics and Statistics Faculty and Staff Publications
In recent years, apparently the Big Bang as described by the Lambda CDM-Standard Model Cosmology has become widely accepted by majority of physics and cosmology communities. Even some people have concluded that it has no serious alternative in horizon. Is that true? First, as we argued elsewhere, Big Bang story relies on singularity. In other words, when we are able to describe the observed data without invoking singularity, then Big Bang model is no longer required. Therefore, here we explore a few alternative stories other than Big Bang story, which most cosmologists believe it is the nearest to Biblical account …
Structure And Magnetism Of Mn5ge3 Nanoparticles, Onur Tosun, Mohammed Salehi-Fashami, Balamurugan Balasubramanian, Ralph Skomski, David J. Sellmyer, George C. Hadjipanayis
Structure And Magnetism Of Mn5ge3 Nanoparticles, Onur Tosun, Mohammed Salehi-Fashami, Balamurugan Balasubramanian, Ralph Skomski, David J. Sellmyer, George C. Hadjipanayis
Nebraska Center for Materials and Nanoscience: Faculty Publications
In this work, we investigated the magnetic and structural properties of isolated Mn5Ge3 nanoparticles prepared by the cluster-beam deposition technique. Particles with sizes between 7.2 and 12.6 nm were produced by varying the argon pressure and power in the cluster gun. X-ray diffraction (XRD)and selected area diffraction (SAD) measurements show that the nanoparticles crystallize in the hexagonal Mn5Si3-type crystal structure, which is also the structure of bulk Mn5Ge3. The temperature dependence of the magnetization shows that the as-made particles are ferromagnetic at room temperature and have slightly different Curie …
Magnetism Of New Metastable Cobalt-Nitride Compounds, Balamuruga Balamurugan, Xin Zhao, Shah R. Valloppilly, Sumit Beniwal, Ralph Skomski, Anandakumar Sarella, Yunlong Jin, Xingzhong Li, Xiaoshan Xu, Huibo Cao, Haohan Wang, Axel Enders, Cai-Zhuang Wang, Kai-Ming Ho, David J. Sellmyer
Magnetism Of New Metastable Cobalt-Nitride Compounds, Balamuruga Balamurugan, Xin Zhao, Shah R. Valloppilly, Sumit Beniwal, Ralph Skomski, Anandakumar Sarella, Yunlong Jin, Xingzhong Li, Xiaoshan Xu, Huibo Cao, Haohan Wang, Axel Enders, Cai-Zhuang Wang, Kai-Ming Ho, David J. Sellmyer
Nebraska Center for Materials and Nanoscience: Faculty Publications
The search for new magnetic materials with high magnetization and magnetocrystalline anisotropy is important for a wide range of applications including information and energy processing. There is only a limited number of naturally occurring magnetic compounds that are suitable. This situation stimulates an exploration of new phases that occur far from thermal-equilibrium conditions, but their stabilization is generally inhibited due to high positive formation energies. Here a nanocluster-deposition method has enabled the discovery of a set of new non-equilibrium Co-N intermetallic compounds. The experimental search was assisted by computational methods including adaptive-genetic-algorithm and electronic- structure calculations. Conventional wisdom is that …
Structural, Magnetic, And Electron-Transport Properties Of Epitaxial Mn2Ptsn Films, Y. Jin, Shah R. Valloppilly, Parashu Kharel, Jace Waybright, Pavel V. Lukashev, Xingzhong Li, David J. Sellmyer
Structural, Magnetic, And Electron-Transport Properties Of Epitaxial Mn2Ptsn Films, Y. Jin, Shah R. Valloppilly, Parashu Kharel, Jace Waybright, Pavel V. Lukashev, Xingzhong Li, David J. Sellmyer
Nebraska Center for Materials and Nanoscience: Faculty Publications
The growth of new magnetic materials on suitable insulating substrates is an important part of the development of spin-electronics devices for memory or information processing. Epitaxial thin films of Mn2PtSn were grown on a MgO [001] substrate by magnetron co-sputtering of the constituents. Structural, magnetic, and electron-transport properties were investigated. The epitaxial Mn2PtSn film has an inverse tetragonal structure with the c-axis aligned in the plane of the MgO substrate. The lattice constants determined using XRD and TEM analysis are c=6.124Å and a=b=4.505Å. The orientation of Mn2PtSn c-axis which …
Gravitational Radiation From A Toroidal Source, Aidan Schumann
Gravitational Radiation From A Toroidal Source, Aidan Schumann
Summer Research
This research uses a linearized form of Einstein's General Relativity to find the quadrupole moment from an oscillating toroidal mass and charge current. With the quadrupole terms, we found the gravitational radiation from the energy distribution. We make the assumptions that we are in the low-energy and far field limits.
Towards A Strong Spin–Orbit Coupling Magnetoelectric Transistor, Peter Dowben, Christian Binek, Kai Zhang, Lu Wang, Wai-Ning Mei, Jonathan P. Bird, Uttam Singisetti, Xia Hong, Kang L. Wang, Dmitri Nikonov
Towards A Strong Spin–Orbit Coupling Magnetoelectric Transistor, Peter Dowben, Christian Binek, Kai Zhang, Lu Wang, Wai-Ning Mei, Jonathan P. Bird, Uttam Singisetti, Xia Hong, Kang L. Wang, Dmitri Nikonov
Peter Dowben Publications
Here, we outline magnetoelectric (ME) device concepts based on the voltage control of the interface magnetism of an ME antiferromagnet gate dielectric formed on a very thin semiconductor channel with large spin–orbit coupling (SOC). The emphasis of the ME spin field-effect transistors (ME spin FET) is on an antiferromagnet spin–orbit read logic device and a ME spin-FET multiplexer. Both spin-FET schemes exploit the strong SOC in the semiconducting channel materials but remain dependent on the voltage-induced switching of an ME, so that the switching time is limited only by the switching dynamics of the ME. The induced exchange field spin …
Spin-Polarized Electron Transmission Through Chiral Halocamphor Molecules, J. M. Dreiling, F. W. Lewis, Timothy J. Gay
Spin-Polarized Electron Transmission Through Chiral Halocamphor Molecules, J. M. Dreiling, F. W. Lewis, Timothy J. Gay
Timothy J. Gay Publications
We have measured electron-circularly-dichroic asymmetries when longitudinally-polarized (chiral) electrons are scattered quasi-elastically by chiral halocamphor molecules: 3-bromocamphor (C10H15BrO), 3-iodocamphor (C10H15IO), and 10-iodocamphor. The proposed dynamic origins of these asymmetries are considered in terms of three classical models related to Mott scattering, target electron helicity density, and spin-other-orbit interactions. The asymmetries observed for 3-bromocamphor and 3-iodocamphor scale roughly as Z2, where Z is the nuclear charge of the heaviest atom in the target molecule, but the scaling is violated by 10- iodocamphor, which has a smaller asymmetry than that for 3-iodocamphor. …