574,519 research outputs found
Many-body Quantum Chaos and Entanglement in a Quantum Ratchet
We uncover signatures of quantum chaos in the many-body dynamics of a
Bose-Einstein condensate-based quantum ratchet in a toroidal trap. We propose
measures including entanglement, condensate depletion, and spreading over a
fixed basis in many-body Hilbert space which quantitatively identify the region
in which quantum chaotic many-body dynamics occurs, where random matrix theory
is limited or inaccessible. With these tools we show that many-body quantum
chaos is neither highly entangled nor delocalized in the Hilbert space,
contrary to conventionally expected signatures of quantum chaos.Comment: 6 pages, 3 figures. 1 tabl
Nozzle fabrication technique
A block of electrically conductive material which is to be formed into a body with internal and/or external surfaces that approximate hyperboloids of one sheet is placed so that its axis is set at a predetermined skew angle with relation to a traveling EDM electrode wire. The electrode wire is then moved into cutting proximity of the body wire. Thereafter, by revolving the body about its own axis, the external and/or internal surfaces of the body will be cut into an approximate hyperbolic surface of revolution depending upon whether the body is positioned with the cutting wire outside of the body or in a previously formed longitudinal passage in the body. As an alternative technique, elongated channels can also be cut into the wall of the body by successively orienting the body to a selected number of angular positions, with the electrode wire being either outside of the body or in a previously formed passage in the body. At each of these angular positions, the electrode wire is moved orthogonally with respect to the axis of the wire, while both the body axis skew angle and the rotational position about that axis is controlled by cutting a channel or groove in the body to relieve stresses in the body material or to convey a coolant fluid
Coupled-cluster calculations for the ground- and excited-states of the spin-half XXZ model
The coupled-cluster method is applied to the spin-1/2 antiferromagnetic XXZ
model on a square lattice by employing an approximation which contains two-body
long-range correlations and high-order four-body local correlations.
Improvement is found for the ground-state energy, sublattice magnetization, and
the critical anisotropy when comparing with the approximation including the
two-body correlations alone. We also obtain the full excitation spectrum which
is in good agreement with the quantum Monte Carlo results and the high-order
spin-wave theory.Comment: 20 pages, 6 figure
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Property in body parts and products of the human body
An intriguing question, which until recently had not been directly explored by the courts, is the extent to which English law recognises body parts and products of the human body as property capable of ownership. Although the common law currently recognises no general property in a dead body (and only limited possessory rights in respect of it), this apparent “no-property rule” provides no justification, it is submitted, for denying proprietary status to parts or products of a living human body. The recent decision of the Court of Appeal in Yearworth v. North Bristol NHS Trust ([2009] EWCA Civ 37) lends strong support to the view that genetic material (as the product of a living human body) is capable of ownership, at least in the context of a claim in the tort of negligence and bailment. This article examines the various issues by reference to both English and Commonwealth authority
Three-body Coulomb breakup of 11Li in the complex scaling method
Coulomb breakup strengths of 11Li into a three-body 9Li+n+n system are
studied in the complex scaling method. We decompose the transition strengths
into the contributions from three-body resonances, two-body ``10Li+n'' and
three-body ``9Li+n+n'' continuum states. In the calculated results, we cannot
find the dipole resonances with a sharp decay width in 11Li. There is a low
energy enhancement in the breakup strength, which is produced by both the two-
and three-body continuum states. The enhancement given by the three-body
continuum states is found to have a strong connection to the halo structure of
11Li. The calculated breakup strength distribution is compared with the
experimental data from MSU, RIKEN and GSI.Comment: RevTeX4, 6 pages, 4 figures, Accepted to Phys. Lett. B DOI
Thermal history modeling of the H chondrite parent body
The cooling histories of individual meteorites can be empirically
reconstructed by using ages from different radioisotopic chronometers with
distinct closure temperatures. For a group of meteorites derived from a single
parent body such data permit the reconstruction of the cooling history and
properties of that body. Particularly suited are H chondrites because precise
radiometric ages over a wide range of closure temperatures are available. A
thermal evolution model for the H chondrite parent body is constructed by using
all H chondrites for which at least three different radiometric ages are
available. Several key parameters determining the thermal evolution of the H
chondrite parent body and the unknown burial depths of the H chondrites are
varied until an optimal fit is obtained. The fit is performed by an 'evolution
algorithm'. Empirical data for eight samples are used for which radiometric
ages are available for at least three different closure temperatures. A set of
parameters for the H chondrite parent body is found that yields excellent
agreement (within error bounds) between the thermal evolution model and
empirical data of six of the examined eight chondrites. The new thermal model
constrains the radius and formation time of the H chondrite parent body
(possibly (6) Hebe), the initial burial depths of the individual H chondrites,
the average surface temperature of the body, the average initial porosity of
the material the body accreted from, and the initial 60Fe content of the H
chondrite parent body.Comment: 16 pages, 7 figure
Fire extinguishing apparatus having a slidable mass for a penetrator nozzle
A fire extinguishing apparatus for delivering an extinguishing agent through a tarrier surrounding a structure into its interior includes an elongated tubular nozzle body which has a pointed penetrating head carried on one end of the tubular body. A source of extinguishing agent coupled to the opposite end of the tubular body is fed through and passes through passages adjacent the head for delivering the extinguishing agent to the interior of the structure. A slidable mass is carried on the tubular body on a remote end of the tubular body from the penetrating head. By manipulating the slidable mass and bringing such in contact with an abutment the force imparted to the tubular body causes the head to penetrate the structure
Overcenter collet space station truss fastener
A quick-connect fastener is arranged with a tubular body that is arranged to be engaged against the exterior surface of a hollow attachment fitting and coincidentally aligned with an opening in the fitting. A collet having normally-contracted fingers with outwardly-enlarged ends is operatively arranged in the body to be moved forwardly by an expander member mounted in the tubular body for advancing the collet fingers through the opening in the attachment fitting. Biasing means are arranged between the expander member and a toggle linkage in the tubular body which is selectively operated to urge the expander member forwardly into engagement with the collet fingers with an initial biasing force to advance their forward portions through the body opening and then expand them outwardly. The biasing means also provide a subsequent biasing force for retaining the collet members in their expanded positions once their enlarged forward end portions are on the opposite side of the body
Quantum codes give counterexamples to the unique pre-image conjecture of the N-representability problem
It is well known that the ground state energy of many-particle Hamiltonians
involving only 2-body interactions can be obtained using constrained
optimizations over density matrices which arise from reducing an N-particle
state. While determining which 2-particle density matrices are "N-
representable" is a computationally hard problem, all known extreme
N-representable 2-particle reduced density matrices arise from a unique
N-particle pre-image, satisfying a conjecture established in 1972. We present
explicit counterexamples to this conjecture through giving Hamiltonians with
2-body interactions which have degenerate ground states that cannot be
distinguished by any 2-body operator. We relate the existence of such
counterexamples to quantum error correction codes and topologically ordered
spin systems.Comment: 4 pages, 1 figur
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