1,428 research outputs found
Entangled spinning particles in charged and rotating black holes
Spin precession for an EPR pair of spin-1/2 particles in equatorial orbits
around a Kerr-Newman black hole is studied. Hovering observers are introduced
to ensure fixed reference frames in order to perform the Wigner rotation. These
observers also guarantee a reliable direction to compare spin states in
rotating black holes. The velocity of the particle due frame-dragging is
explicitly incorporated by addition of velocities with respect the hovering
observers and the corresponding spin precession angle is computed. The
spin-singlet state is observed to be mixed with the spin-triplet by dynamical
and gravity effects, thus it is found that a perfect anti-correlation of
entangled states for these observers is deteriorated. Finally, an analysis
concerning the different limit cases of parameters of spin precession including
the frame-dragging effects is carried out.Comment: 25+1 pages, 7 eps figures. Major changes were made through all the
manuscript. Clarifications regarding modifications were introduced through
the draft. Figures were changed and reduced in number. arXiv admin note: text
overlap with arXiv:quant-ph/030711
Opening up the Quantum Three-Box Problem with Undetectable Measurements
One of the most striking features of quantum mechanics is the profound effect
exerted by measurements alone. Sophisticated quantum control is now available
in several experimental systems, exposing discrepancies between quantum and
classical mechanics whenever measurement induces disturbance of the
interrogated system. In practice, such discrepancies may frequently be
explained as the back-action required by quantum mechanics adding quantum noise
to a classical signal. Here we implement the 'three-box' quantum game of
Aharonov and Vaidman in which quantum measurements add no detectable noise to a
classical signal, by utilising state-of-the-art control and measurement of the
nitrogen vacancy centre in diamond.
Quantum and classical mechanics then make contradictory predictions for the
same experimental procedure, however classical observers cannot invoke
measurement-induced disturbance to explain this discrepancy. We quantify the
residual disturbance of our measurements and obtain data that rule out any
classical model by > 7.8 standard deviations, allowing us for the first time to
exclude the property of macroscopic state-definiteness from our system. Our
experiment is then equivalent to a Kochen-Spekker test of quantum
non-contextuality that successfully addresses the measurement detectability
loophole
Understanding the evolution of native pinewoods in Scotland will benefit their future management and conservation
Scots pine (Pinus sylvestris L.) is a foundation species in Scottish highland forests and a national icon. Due to heavy exploitation, the current native pinewood coverage represents a small fraction of the postglacial maximum. To reverse this decline, various schemes have been initiated to promote planting of new and expansion of old pinewoods. This includes the designation of seed zones for control of the remaining genetic resources. The zoning was based mainly on biochemical similarity among pinewoods but, by definition, neutral molecular markers do not reflect local phenotypic adaptation. Environmental variation within Scotland is substantial and it is not yet clear to what extent this has shaped patterns of adaptive differentiation among Scottish populations. Systematic, rangewide common-environment trials can provide insights into the evolution of the native pinewoods, indicating how environment has influenced phenotypic variation and how variation is maintained. Careful design of such experiments can also provide data on the history and connectivity among populations, by molecular marker analysis. Together, phenotypic and molecular datasets from such trials can provide a robust basis for refining seed transfer guidelines for Scots pine in Scotland and should form the scientific basis for conservation action on this nationally important habitat
r-PROCESS CALCULATIONS WITH A MICROSCOPIC DESCRIPTION OF THE FISSION PROCESS
We computed the fission properties of nuclei in the range of 84 ≤
Z ≤ 120 and 118 ≤ N ≤ 250 using the Barcelona–Catania–Paris–Madrid
(BCPM) Energy Density Functional (EDF). For the first time, a set of
spontaneous and neutron-induced fission rates were obtained from a microscopic calculation of nuclear collective inertias. These fission rates were
used as a nuclear input in the estimation of nucleosynthesis yields on neutron star mergers. We founded that the increased stability against the
fission process predicted by the BCPM allows the formation of nuclei up
to A = 286. This constitutes a first step in a systematic exploration of
different sets of fission rates on r-process abundance predictionsS.A.G., G.M.P. and M.-R.W. acknowledge support from the Helmholtz
Association through the Nuclear Astrophysics Virtual Institute (VH-VI417), and the BMBF-Verbundforschungsprojekt number 05P15RDFN1.
M.-R.W. acknowledges support from the Villum Foundation (Project No.
13164) and the Danish National Research Foundation (DNRF91). The work
of L.M.R. was supported in part by the Spanish Ministerio de EconomĂa y
Competitividad (MINECO), under contracts Nos. FIS2012-34479, FPA2015-
65929, FIS2015-63770 and by the Consolider-Ingenio 2010 Program MULTIDAR
Exactly solvable pairing Hamiltonian for heavy nuclei
We present a new exactly solvable Hamiltonian with a separable pairing
interaction and non-degenerate single-particle energies. It is derived from the
hyperbolic family of Richardson-Gaudin models and possesses two free
parameters, one related to an interaction cutoff and the other to the pairing
strength. These two parameters can be adjusted to give an excellent
reproduction of Gogny self-consistent mean-field calculations in the canonical
basis.Comment: 4 pages, 3 figure
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