1,990 research outputs found
Quantum Stability of the Phase Transition in Rigid QED
Rigid QED is a renormalizable generalization of Feynman's space-time action
characterized by the addition of the curvature of the world line (rigidity). We
have recently shown that a phase transition occurs in the leading approximation
of the large N limit. The disordered phase essentially coincides with ordinary
QED, while the ordered phase is a new theory. We have further shown that both
phases of the quantum theory are free of ghosts and tachyons. In this letter,
we study the first sub-leading quantum corrections leading to the renormalized
mass gap equation. Our main result is that the phase transition does indeed
survive these quantum fluctuations.Comment: PHYZZX, 9 pages, 3 Postscript figures, to be published in Nucl. Phys.
Characterising a solid state qubit via environmental noise
We propose a method for characterising the energy level structure of a
solid-state qubit by monitoring the noise level in its environment. We consider
a model persistent-current qubit in a lossy resevoir and demonstrate that the
noise in a classical bias field is a sensitive function of the applied field.Comment: 3 Figure
The absolutely continuous spectrum of one-dimensional Schr"odinger operators
This paper deals with general structural properties of one-dimensional
Schr"odinger operators with some absolutely continuous spectrum. The basic
result says that the omega limit points of the potential under the shift map
are reflectionless on the support of the absolutely continuous part of the
spectral measure. This implies an Oracle Theorem for such potentials and
Denisov-Rakhmanov type theorems.
In the discrete case, for Jacobi operators, these issues were discussed in my
recent paper [19]. The treatment of the continuous case in the present paper
depends on the same basic ideas.Comment: references added; a few very minor change
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Production and Characterization of Atomized U-Mo Powder by the Rotating Electrode Process
In order to produce feedstock fuel powder for irradiation testing, the Idaho National Laboratory has produced a rotating electrode type atomizer to fabricate uranium-molybdenum alloy fuel. Operating with the appropriate parameters, this laboratory-scale atomizer produces fuel in the desired size range for the RERTR dispersion experiments. Analysis of the powder shows a homogenous, rapidly solidified microstructure with fine equiaxed grains. This powder has been used to produce irradiation experiments to further test adjusted matrix U-Mo dispersion fuel
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U-Mo Foil/Cladding Interactions in Friction Stir Welded Monolithic RERTR Fuel Plates
Interaction between U-Mo fuel and Al has proven to dramatically impact the overall irradiation performance of RERTR dispersion fuels. It is of interest to better understand how similar interactions may affect the performance of monolithic fuel plates, where a uranium alloy fuel is sandwiched between aluminum alloy cladding. The monolithic fuel plate removes the fuel matrix entirely, which reduces the total surface area of the fuel that is available to react with the aluminum and moves the interface between the fuel and cladding to a colder region of the fuel plate. One of the major fabrication techniques for producing monolithic fuel plates is friction stir welding. This paper will discuss the interactions that can occur between the U-Mo foil and 6061 Al cladding when applying this fabrication technique. It has been determined that the time at high temperatures should be limited as much as is possible during fabrication or any post-fabrication treatment to reduce as much as possible the interactions between the foil and cladding. Without careful control of the fabrication process, significant interaction between the U-Mo foil and Al alloy cladding can result. The reaction layers produced from such interactions can exhibit notably different morphologies vis-Ã -vis those typically observed for dispersion fuels
Energy downconversion between classical electromagnetic fields via a quantum mechanical SQUID ring
We consider the interaction of a quantum mechanical SQUID ring with a classical resonator (a parallel LC tank circuit). In our model we assume that the evolution of the ring maintains its quantum mechanical nature, even though the circuit to which it is coupled is treated classically. We show that when the SQUID ring is driven by a classical monochromatic microwave source, energy can be transferred between this input and the tank circuit, even when the frequency ratio between them is very large. Essentially, these calculations deal with the coupling between a single macroscopic quantum object (the SQUID ring) and a classical circuit measurement device where due account is taken of the nonperturbative behavior of the ring and the concomitant nonlinear interaction of the ring with this device
Characterising a solid state qubit via environmental noise
We propose a method for characterising the energy level structure of a solid state qubit by monitoring the noise level in its environment. We consider a model persistent current qubit in a lossy reservoir and demonstrate that the noise in a classical bias field is a sensitive function of the applied field
Mesoscopic Josephson arrays interacting with non-classical electromagnetic fields and their applications
A ring made from a Josephson array in the insulating phase is considered. The ring
contains a ‘dual Josephson junction’ (Josephson junction for vortices). External non-classical
electromagnetic fields are coupled to the device and interact with the vortices that circulate the ring.
The time evolution of ths two-mode fully quantum mechanical system is studied. The effect of the
quantum statistics of the photons on the quantum statistics of the vortices is discussed. The
entanglement between the two systems is quantified
Colorless States in Perturbative QCD: Charmonium and Rapidity Gaps
We point out that an unorthodox way to describe the production of rapidity
gaps in deep inelastic scattering, recently proposed by Buchm\"uller and
Hebecker, suggests a description of the production of heavy quark bound states
which is in agreement with data. The approach questions the conventional
treatment of the color quantum number in perturbative QCD.Comment: 14 pages, plain Latex, 9 postscript figures included. Uses epsf.sty.
Postscript file of paper with figures also available at
http://phenom.physics.wisc.edu/pub/preprints/1995/madph-95-919.ps.Z or at
ftp://phenom.physics.wisc.edu/pub/preprints/1995/madph-95-919.ps.
Persistent entanglement in the classical limit
The apparent difficulty in recovering classical nonlinear dynamics and chaos from standard quantum mechanics has been the subject of a great deal of interest over the last 20 years. For open quantum systems—those coupled to a dissipative environment and/or a measurement device—it has been demonstrated that chaotic-like behaviour can be recovered in the appropriate classical limit. In this paper, we investigate the entanglement generated between two nonlinear oscillators, coupled to each other and to their environment. Entanglement—the inability to factorize coupled quantum systems into their constituent parts—is one of the defining features of quantum mechanics. Indeed, it underpins many of the recent developments in quantum technologies. Here, we show that the entanglement characteristics of two 'classical' states (chaotic and periodic solutions) differ significantly in the classical limit. In particular, we show that significant levels of entanglement are preserved only in the chaotic-like solutions
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