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Your search keyword '"Weidman, P. D."' showing total 28 results
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28 results on '"Weidman, P. D."'

1. Coulomb interaction-driven entanglement of electrons on helium

Author

Beysengulov, Niyaz R., Pollanen, Johannes, Schøyen, Øyvind S., Bilek, Stian D., Flaten, Jonas B., Leinonen, Oskar, Kristiansen, Håkon Emil, Stewart, Zachary J., Weidman, Jared D., Wilson, Angela K., and Hjorth-Jensen, Morten

Subjects
Quantum Physics, Condensed Matter - Mesoscale and Nanoscale Physics, Physics - Atomic Physics
Abstract

The generation and evolution of entanglement in quantum many-body systems is an active area of research that spans multiple fields, from quantum information science to the simulation of quantum many-body systems encountered in condensed matter, subatomic physics, and quantum chemistry. Motivated by recent experiments exploring quantum information processing systems with electrons trapped above the surface of cryogenic noble gas substrates, we theoretically investigate the generation of \emph{motional} entanglement between two electrons via their unscreened Coulomb interaction. The model system consists of two electrons confined in separate electrostatic traps which establish microwave frequency quantized states of their motion. We compute the motional energy spectra of the electrons, as well as their entanglement, by diagonalizing the model Hamiltonian with respect to a single-particle Hartree product basis. This computational procedure can in turn be employed for device design and guidance of experimental implementations. In particular, the theoretical tools developed here can be used for fine tuning and optimization of control parameters in future experiments with electrons trapped above the surface of superfluid helium or solid neon., Comment: Revised figures and discussions

Published
2023

17. On super free fall.

Author

Higuera Antón, Francisco, Medina, A., Weidman, P. D., Higuera Antón, Francisco, Medina, A., and Weidman, P. D.

Abstract

Villermaux & Pomeau (J. Fluid Mech., vol. 642, 2010, p. 147) analysed the motion of the interface of an inviscid liquid column released from rest in a vertical tube whose area expands gradually downwards, with application to an inverted conical container for which experimental measurements were carried out. An error in the analysis is found and corrected in the present investigation, which provides the new governing equation for the super-accelerated interface motion down gradually varying tubes in general, and integrated results for interface trajectories, velocities and accelerations down a conical tube in particular. Interestingly, the error does not affect any of the conclusions given in the 2010 paper. Further new results are reported here such as the equation governing the centre of mass and proof that the end point acceleration is exactly that of gravity

Published
2013

18. Prototypical Transition-Metal Carbenes, (CO)5Cr═CH2, (CO)4Fe═CH2, (CO)3Ni═CH2, (CO)5Mo═CH2, (CO)4Ru═CH2, (CO)3Pd═CH2, (CO)5W═CH2, (CO)4Os═CH2, and (CO)3Pt═CH2: Challenge to Experiment

Author

Weidman, Jared D., Estep, Marissa L., and Schaefer, Henry F.

Abstract

Transition-metal carbenes are useful in organometallic chemistry due to their demonstrated use as catalysts in carbon–carbon bond-forming reactions. Yet the prototypical transition-metal carbenes, consisting of a single metal center doubly bonded to a methylene ligand and surrounded by carbonyls, have been elusive to experimental synthesis. This theoretical work examines the structures and properties of nine prototypical transition-metal carbenes. Optimized values for M═CH2bond lengths, dissociation energies, and vibrational frequencies are reported. The M═CH2bond distances range from 1.81 (Ni) to 2.05 Å (Pd). The M═CH2dissociation energies fall in the range of 16.4 (Pd) to 92.3 kcal mol–1(Os). The spectroscopic observation of several of these molecules should be possible.

Published
2018
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19. Quasi-steady vortical structures in vertically vibrating soap �lms

Author

Vega de Prada, José Manuel, Higuera Antón, Francisco, Weidman, P. D., Vega de Prada, José Manuel, Higuera Antón, Francisco, and Weidman, P. D.

Abstract

An analysis of the quasi-steady streaming of the liquid in a vertically vibrated horizontal soap film is reported. The air around the soap film is seen to play a variety of roles: it transmits normal and tangential oscillatory stresses to the film, damps out Marangoni waves, and forces non-oscillatory deflection of the film and tangential motion of the liquid. Non-oscillatory volume forcing originating inside the liquid is also analysed. This forcing dominates the quasi-steady streaming when the excitation frequency is close to the eigenfrequency of a Marangoni mode of the soap film, while both volume forcing in the liquid and surface forcing of the gas on the liquid are important when no Marangoni mode resonates. Different manners by which the combined forcings can induce quasi-steady streaming motion are discussed and some numerical simulations of the quasi-steady liquid flow are presented.

Published
1998

20. On the Instability of Spheres Settling through a Vertical Pipe Filled with HPG.

Author

Weidman, P. D., Roberts, B., and Eisen, S.

Subjects
OSCILLATIONS, AERODYNAMICS, SPHERES, HELICAL waveguides, TUBES, WATER, FLUIDS, EXPERIMENTS
Abstract

An extensive set of experiments were performed to determine the stability boundary for the longitudinal oscillation of steel spheres settling through Hydroxy Propyl Guar (HPG) contained in long vertical tubes, a phenomenon first reported by Mollinger, et al. (1999). Results are reported in d/D-pH parameter space, where d is the sphere diameter and D is the internal diameter of a tube. Longitudinal oscillations, which owe their existence to the self-healing nature of the gel, occur over the region 0.48 < d/D < 0.86 and 8.31 < pH < 8.82. We discover that the upper pH limit of this stability domain is linked to the HPG gel point. During the course of experimentation, additional instabilities in the form of high-frequency transverse oscillations or helical motions were discovered and documented. The pure transverse oscillations found in the domain 8.035 < pH < 8.31 and 0.9 < d/D < 0.6 result from the elastic nature of the guar in this region. For 6.25 < pH < 8.035 transverse oscillations or stable descents are interspersed between bands of tight helical motion at large d/D and wide helical motion at low d/D. At the lowest value pH = 6.25 the guar is a Newtonian fluid, yet the spiral motion persists in small bands of d/D. We have verified, in the literature and through additional experiments using distilled water as the Newtonian liquid that the spiral motion of spheres falling inside vertical tubes does indeed exist. [ABSTRACT FROM AUTHOR]

Published
2012
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