34,752 research outputs found
Fast and robust two-qubit gates for scalable ion trap quantum computing
We propose a new concept for a two-qubit gate operating on a pair of trapped
ions based on laser coherent control techniques. The gate is insensitive to the
temperature of the ions, works also outside the Lamb-Dicke regime, requires no
individual addressing by lasers, and can be orders of magnitude faster than the
trap period
Gravi-Weak Unification and the Black-Hole-Hedgehog's Solution with Magnetic Field Contribution
In the present paper, we investigated the gravitational black-hole-hedgehog's
solution with magnetic field contribution in the framework of the f(R)--gravity
described by the Gravi-Weak unification model. Assuming the Multiple Point
Principle (MPP), we considered the existence of the two degenerate vacua of the
Universe: the first Electroweak (EW) vacuum with GeV ("true
vacuum"), and the second Planck scale ("false vacuum") with
GeV. In these vacua, we investigated different topological defects. The main
aim of this paper is an investigation of the black-hole-hedgehog configurations
as defects of the "false vacuum". We have obtained the solution which
corresponds to a global monopole, that has been "swallowed" by the black-hole
with core mass and radius
We investigated the metric in
the vicinity of the black-hole-hedgehog and estimated its horizon radius:
. We have considered the phase transition from the
"false vacuum" to the "true vacuum" and confirmed the stability of the
EW--vacuum.Comment: 22 pages. arXiv admin note: text overlap with arXiv:1703.05594,
arXiv:1801.06979, arXiv:1605.01169; text overlap with arXiv:1002.4275 by
other author
Entanglement Detection Using Majorization Uncertainty Bounds
Entanglement detection criteria are developed within the framework of the
majorization formulation of uncertainty. The primary results are two theorems
asserting linear and nonlinear separability criteria based on majorization
relations, the violation of which would imply entanglement. Corollaries to
these theorems yield infinite sets of scalar entanglement detection criteria
based on quasi-entropic measures of disorder. Examples are analyzed to probe
the efficacy of the derived criteria in detecting the entanglement of bipartite
Werner states. Characteristics of the majorization relation as a comparator of
disorder uniquely suited to information-theoretical applications are emphasized
throughout.Comment: 10 pages, 1 figur
Why Nature has made a choice of one time and three space coordinates?
We propose a possible answer to one of the most exciting open questions in
physics and cosmology, that is the question why we seem to experience four-
dimensional space-time with three ordinary and one time dimensions. We have
known for more than 70 years that (elementary) particles have spin degrees of
freedom, we also know that besides spin they also have charge degrees of
freedom, both degrees of freedom in addition to the position and momentum
degrees of freedom. We may call these ''internal degrees of freedom '' the
''internal space'' and we can think of all the different particles, like quarks
and leptons, as being different internal states of the same particle. The
question then naturally arises: Is the choice of the Minkowski metric and the
four-dimensional space-time influenced by the ''internal space''?
Making assumptions (such as particles being in first approximation massless)
about the equations of motion, we argue for restrictions on the number of space
and time dimensions. (Actually the Standard model predicts and experiments
confirm that elementary particles are massless until interactions switch on
masses.)
Accepting our explanation of the space-time signature and the number of
dimensions would be a point supporting (further) the importance of the
''internal space''.Comment: 13 pages, LaTe
Chiral Anomaly and Classical Negative Magnetoresistance of Weyl Metals
We consider the classical magnetoresistance of a Weyl metal in which the
electron Fermi surface possess nonzero fluxes of the Berry curvature. Such a
system may exhibit large negative magnetoresistance with unusual anisotropy as
a function of the angle between the electric and magnetic fields. In this case
the system can support a new type of plasma waves. These phenomena are
consequences of chiral anomaly in electron transport theory.Comment: 4 pages, 2 figure
Topological Structure of the Vacuum, Cosmological Constant and Dark Energy
In this review we present a theory of cosmological constant and Dark Energy
(DE), based on the topological structure of the vacuum. The Multiple Point
Principle (MPP) is reviewed. It demonstrates the existence of the two vacua
into the SM. The Froggatt-Nielsen's prediction of the top-quark and Higgs
masses is given in the assumption that there exist two degenerate vacua in the
SM. This prediction was improved by the next order calculations. We also
considered B.G. Sidharth's theory of cosmological constant based on the
non-commutative geometry of the Planck scale space-time, what gives an
extremely small DE density providing the accelerating expansion of the
Universe. Theory of two degenerate vacua - the Planck scale phase and
Electroweak (EW) phase - also is reviewed, topological defects in these vacua
are investigated, also the Compton wavelength phase suggested by B.G. Sidharth
was discussed. A general theory of the phase transition and the problem of the
vacuum stability in the SM is reviewed. Assuming that the recently discovered
at the LHC new resonance with mass GeV is a new scalar
bound state , earlier predicted by C.D. Froggatt, H.B. Nielsen
and L.V. Laperashvili, we try to provide the vacuum stability in the SM and
exact accuracy of the MPP.Comment: 37 pages and 7 figures. arXiv admin note: text overlap with
arXiv:1601.03231; text overlap with arXiv:1302.2716 by other author
Multiple Quantum NMR and Entanglement Dynamics in Dipolar Coupling Spin
We investigate numerically the time dependence of the multiple quantum
coherences and entanglement in linear chains up to nine nuclear spins of 1/2
coupled by the dipole-dipole interactions. Two models are considered: (1) a
spin chain with nearest-neighbor dipole -dipole interactions; (2) a more
realistic model with interactions between all spins. It is shown that the
entangled states appear between remote particles which do not interact directly
(model 1), while the interaction between all spins (model 2) not always results
in entanglement between remote spins.Comment: 14 pages, 3 figures. accepted for publication in Physical Review
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