1,995 research outputs found
N-qubit states as points on the Bloch sphere
We show how the Majorana representation can be used to express the pure
states of an N-qubit system as points on the Bloch sphere. We compare this
geometrical representation of N-qubit states with an alternative one, proposed
recently by the present authors.Comment: 9 pages, 2 figures, contribution to CEWQO 2009 proceedings. v2: Minor
changes, published versio
Spacetime Foam Model of the Schwarzschild Horizon
We consider a spacetime foam model of the Schwarzschild horizon, where the
horizon consists of Planck size black holes. According to our model the entropy
of the Schwarzschild black hole is proportional to the area of its event
horizon. It is possible to express geometrical arguments to the effect that the
constant of proportionality is, in natural units, equal to one quarter.Comment: 16 pages, 2 figures, improved and extended version with some
significant changes. Accepted for publication in Phys.Rev.
Inert states of spin-S systems
We present a simple but efficient geometrical method for determining the
inert states of spin-S systems. It can be used if the system is described by a
spin vector of a spin-S particle and its energy is invariant in spin rotations
and phase changes. Our method is applicable to an arbitrary S and it is based
on the representation of a pure spin state of a spin-S particle in terms of 2S
points on the surface of a sphere. We use this method to find candidates for
some of the ground states of spinor Bose-Einstein condensates.Comment: 4 pages, 2 figures, minor changes, references added, typos correcte
Explicit expressions for the topological defects of spinor Bose-Einstein condensates
In this paper we first derive a general method which enables one to create
expressions for vortices and monopoles. By using this method we construct
several order-parameters describing the vortices and monopoles of Bose-Einstein
condensates with hyperfine spin F=1 and F=2. We concentrate on defects which
are topologically stable in the absence of an external magnetic field. In
particular we show that in a ferromagnetic condensate there can be a vortex
which does not produce any superfluid flow. We also point out that the
order-parameter space of the cyclic phase of F=2 condensate consists of two
disconnected sets. Finally we examine the effect of an external magnetic field
on the vortices of a ferromagnetic F=1 condensate and discuss the experimental
preparation of a vortex in this system.Comment: 17 pages, partly rewritten to improve clarity, conclusions unchange
Microscopic Black Hole Pairs in Highly-Excited States
We consider the quantum mechanics of a system consisting of two identical,
Planck-size Schwarzschild black holes revolving around their common center of
mass. We find that even in a very highly-excited state such a system has very
sharp, discrete energy eigenstates, and the system performs very rapid
transitions from a one stationary state to another. For instance, when the
system is in the 100th excited state, the life times of the energy eigenstates
are of the order of s, and the energies of gravitons released in
transitions between nearby states are of the order of eV.Comment: 22 pages, 3 figures, uses RevTe
Quantum-mechanical model of the Kerr-Newman black hole
We consider a Hamiltonian quantum theory of stationary spacetimes containing
a Kerr-Newman black hole. The physical phase space of such spacetimes is just
six-dimensional, and it is spanned by the mass , the electric charge and
angular momentum of the hole, together with the corresponding canonical
momenta. In this six-dimensional phase space we perform a canonical
transformation such that the resulting configuration variables describe the
dynamical properties of Kerr-Newman black holes in a natural manner. The
classical Hamiltonian written in terms of these variables and their conjugate
momenta is replaced by the corresponding self-adjoint Hamiltonian operator and
an eigenvalue equation for the Arnowitt-Deser-Misner (ADM) mass of the hole,
from the point of view of a distant observer at rest, is obtained. In a certain
very restricted sense, this eigenvalue equation may be viewed as a sort of
"Schr\"odinger equation of black holes". Our "Schr\"odinger equation" implies
that the ADM mass, electric charge and angular momentum spectra of black holes
are discrete, and the mass spectrum is bounded from below. Moreover, the
spectrum of the quantity , where is the angular momentum per
unit mass of the hole, is strictly positive when an appropriate self-adjoint
extension is chosen. The WKB analysis yields the result that the large
eigenvalues of , and are of the form , where is an
integer. It turns out that this result is closely related to Bekenstein's
proposal on the discrete horizon area spectrum of black holes.Comment: 30 pages, 3 figures, RevTe
Application of UAV multispectral imaging for determining the characteristics of maize vegetation
Received: February 1st, 2023 ; Accepted: April 25th, 2023 ; Published: May 10th, 2023 ; Correspondence: [email protected] in forage maize (Zea mays L.) cultivation for livestock feed has grown in
northern conditions. In addition, it is important to develop methods and tools to monitor crop
development and other characteristics of the crop. For these purposes UAVs are very efficient
and versatile tools. UAVs can be equipped with a variety of sensors like lidar or different types
of cameras. Several studies have been conducted where data collected by UAVs are used to
estimate different crop properties like yield and biomass. In this research, a forage maize field
experiment was studied to examine how well the aerial multispectral data correlated with the
different properties of the vegetation. The field test site is located in Helsinki, Finland.
A multispectral camera (MicaSense Rededge 3) was used to take images from five spectral bands
(Red, Green, Blue, Rededge and NIR). All the images were processed with Pix4D software to
generate orthomosaic images. Several vegetation indices were calculated from the five spectral
bands. During the growing season, crop height, chlorophyll content, leaf area index (LAI), fresh
and dry matter biomass were measured from the vegetation. From the five spectral bands,
Rededge had the highest correlation with fresh biomass (R2 = 0.273). The highest correlation for
a vegetation index was found between NDRE and chlorophyll content (R2 = 0.809). A multiple
linear regression (MLR) model using selected spectral bands and vegetation indices as inputs
showed high correlations with the field measurements
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