Integral relations for solutions of the confluent Heun equation [CBPF-NF--010/2014] 651 KB - http://www.iaea.org/inis/collection/NCLCollectionStore/_Public/46/105/46105481.pdf - Text Version by Links, J. (Centre for Mathematical Physics, School of Physical Sciences, The University
of Queensland (Australia)); Foerster, A.; Tonel, A.; Santos, G. (Instituto de F´ısica
da UFRGS, Porto Alegre, RS (Brazil)); Centro Brasileiro de Pesquisas Fisicas (CBPF), Rio de Janeiro, RJ (Brazil) Read MoreCollapse
[en]
The two-site Bose–Hubbard model is a simple model used to study Josephson tunneling
between two Bose–Einstein condensates. In this work we give an overview of some
mathematical aspects of this model. Using a classical analysis, we study the equations
of motion and the level curves of the Hamiltonian. Then, the quantum dynamics of the
model is investigated using direct diagonalization of the Hamiltonian. In both of
these analyses, the existence of a threshold coupling between a delocalised and a
self-trapped phase is evident, in qualitative agreement with experiments. We end with
a discussion of the exact solvability of the model via the algebraic Bethe Ansatz.
(author)$$$$
Greybody factors for Myers–Perry black holes http://dx.doi.org/10.1063/1.4901127 by Boonserm, Petarpa (Department of Mathematics and Computer Science, Faculty of Science,
Chulalongkorn University, Phayathai Road, Patumwan, Bangkok 10330 (Thailand)); Chatrabhuti,
Auttakit; Ngampitipan, Tritos (Particle Physics Research Laboratory, Department of
Physics, Faculty of Science, Chulalongkorn University, Phayathai Road, Patumwan, Bangkok
10330 (Thailand)); Visser, Matt (School of Mathematics, Statistics, and Operations
Research, Victoria University of Wellington, PO Box 600, Wellington 6140 (New Zealand)),
E-mail: petarpa.boonserm@gmail.com, E-mail: dma3ac2@gmail.com, E-mail: tritos.ngampitipan@gmail.com,
E-mail: matt.visser@msor.vuw.ac.nz Read MoreCollapse
[en]
The Myers–Perry black holes are higher-dimensional generalizations of the usual
(3+1)-dimensional rotating Kerr black hole. They are of considerable interest in Kaluza–Klein
models, specifically within the context of brane-world versions thereof. In the present
article, we shall consider the greybody factors associated with scalar field excitations
of the Myers–Perry spacetimes, and develop some rigorous bounds on these greybody
factors. These bounds are of relevance for characterizing both the higher-dimensional
Hawking radiation, and the super-radiance, that is expected for these spacetimes$$$$
This work is concerned with stability of equilibria in the homogeneous (equal frequencies)
Kuramoto model of weakly coupled oscillators. In 2012 [R. Taylor, J. Phys. A: Math.
Theor. 45, 1–15 (2012)], a sufficient condition for almost global synchronization
was found in terms of the minimum degree–order ratio of the graph. In this work,
a new lower bound for this ratio is given. The improvement is achieved by a concrete
infinite sequence of regular graphs. Besides, non standard unstable equilibria of
the graphs studied in Wiley et al. [Chaos 16, 015103 (2006)] are shown to exist as
conjectured in that work$$$$
Recent developments in the theory of plasma-based collisionally excited x-ray lasers
(XRL) have shown an optimization potential based on the dependence of the absorption
region of the pumping laser on its angle of incidence on the plasma. For the experimental
proof of this idea, a number of diagnostic schemes were developed, tested, qualified
and applied. A high-resolution imaging system, yielding the keV emission profile perpendicular
to the target surface, provided positions of the hottest plasma regions, interesting
for the benchmarking of plasma simulation codes. The implementation of a highly efficient
spectrometer for the plasma emission made it possible to gain information about the
abundance of the ionization states necessary for the laser action in the plasma. The
intensity distribution and deflection angle of the pump laser beam could be imaged
for single XRL shots, giving access to its refraction process within the plasma. During
a European collaboration campaign at the Lund Laser Center, Sweden, the optimization
of the pumping laser incidence angle resulted in a reduction of the required pumping
energy for a Ni-like Mo XRL, which enabled the operation at a repetition rate of 10
Hz. Using the experiences gained there, the XRL performance at the PHELIX facility,
GSI Darmstadt with respect to achievable repetition rate and at wavelengths below
20 nm was significantly improved, and also important information for the development
towards multi-100 eV plasma XRLs was acquired. Due to the setup improvements achieved
during the work for this thesis, the PHELIX XRL system now has reached a degree of
reproducibility and versatility which is sufficient for demanding applications like
the XRL spectroscopy of heavy ions. In addition, a European research campaign, aiming
towards plasma XRLs approaching the water-window (wavelengths below 5 nm) was initiated.
(orig.)$$$$
The aim of the presented experiment was to investigate the feasibility of satellite-based
global quantum key distribution. In this context, a free-space quantum key distribution
experiment over a real distance of 144 km was performed. The transmitter and the receiver
were situated in 2500 m altitude on the Canary Islands of La Palma and Tenerife, respectively.
The small and compact transmitter unit generated attenuated laser pulses, that were
sent to the receiver via a 15-cm optical telescope. The receiver unit for polarisation
analysis and detection of the sent pulses was integrated into an existing mirror telescope
designed for classical optical satellite communications. To ensure the required stability
and efficiency of the optical link in the presence of atmospheric turbulence, the
two telescopes were equipped with a bi-directional automatic tracking system. Still,
due to stray light and high optical attenuation, secure key exchange would not be
possible using attenuated pulses in connection with the standard BB84 protocol. The
photon number statistics of attenuated pulses follows a Poissonian distribution. Hence,
by removing a photon from all pulses containing two or more photons, an eavesdropper
could measure its polarisation without disturbing the polarisation state of the remaining
pulse. In this way, he can gain information about the key without introducing detectable
errors. To protect against such attacks, the presented experiment employed the recently
developed method of using additional ''decoy'' states, i.e., the the intensity of
the pulses created by the transmitter were varied in a random manner. By analysing
the detection probabilities of the different pulses individually, a photon-number-splitting
attack can be detected. Thanks to the decoy-state analysis, the secrecy of the resulting
quantum key could be ensured despite the Poissonian nature of the emitted pulses.
For a channel attenuation as high as 35 dB, a secret key rate of up to 250 bit/s was
achieved. Our outdoor experiment was carried out under real atmospheric conditions
and with a channel attenuation comparable to an optical link from ground to a satellite
in low earth orbit. Hence, it definitely shows the feasibility of satellite-based
quantum key distribution using a technologically comparatively simple system. (orig.)$$$$
Constant curvature surfaces of the supersymmetric ℂP^{N−1} sigma
model http://dx.doi.org/10.1063/1.4907868 by Delisle, L. (Département de Mathématiques et de Statistique, Université
de Montréal, C.P. 6128, Succ. Centre-ville, Montréal, Québec H3C 3J7
(Canada)); Hussin, V. (Département de Mathématiques et de Statistique, Université
de Montréal, C.P. 6128, Succ. Centre-ville, Montréal, Québec H3C 3J7
(Canada); Centre de Recherches Mathématiques, Université de Montréal,
C.P. 6128, Succ. Centre-ville, Montréal, Québec H3C 3J7 (Canada)); Yurduşen,
İ. (Department of Mathematics, Hacettepe University, 06800 Beytepe, Ankara (Turkey));
Zakrzewski, W. J. (Department of Mathematical Sciences, University of Durham, Durham
DH1 3LE,United Kingdom (United Kingdom)), E-mail: delisle@dms.umontreal.ca, E-mail:
hussin@dms.umontreal.ca, E-mail: yurdusen@hacettepe.edu.tr, E-mail: w.j.zakrzewski@durham.ac.uk Read MoreCollapse
[en]
Constant curvature surfaces are constructed from the finite action solutions of the
supersymmetric ℂP^{N−1} sigma model. It is shown that there is
a unique holomorphic solution which leads to constant curvature surfaces: the generalized
Veronese curve. We give a general criterion to construct non-holomorphic solutions
of the model. We extend our analysis to general supersymmetric Grassmannian models$$$$
A remarkable variety of particle acceleration occurs in the solar system, from lightning-related
acceleration of electrons to tens of MeV energy in less than a millisecond in planetary
atmospheres; to acceleration of auroral and radiation belt particles in planetary
magnetospheres; to acceleration at planetary bow shocks, co-rotating interplanetary
region shocks, shocks driven by fast coronal mass ejections, and at the heliospheric
termination shock; to acceleration in magnetic reconnection regions in solar flares
and at planetary magnetopause and magnetotail current sheets. These acceleration processes
often occur in conjunction with transient energy releases, and some are very efficient,
with the accelerated particles containing ∼ 10-50% of the total energy released. Others
are highly selective; for example, the acceleration in ^{3}He-rich solar particle
events enriches ^{3}He by a factor of up to 10,000 or more relative to ^{4}He.
Unlike acceleration processes outside the solar system, the accelerated particles
and the physical conditions in the acceleration region can be studied through direct
in situ measurements, and/or through detailed imaging and spectroscopy. Here I review
recent observations of these acceleration phenomena, our current understanding of
the physics involved, and the applicability to particle acceleration elsewhere in
the universe. (author)$$$$
The equations of fluid mechanics, coupled with those that describe matter transportation
at the molecular level must be handled effectively. Putting the fluid into equations,
we model the Bloch NMR flow equations into the harmonic wave equation for the analysis
of general fluid flow. We derived the solution of the modelled harmonic equation in
non relativistic quantum mechanics and discuss its semi classical application to illustrate
its potential wide-ranging usefulness in the search for the best possible data obtainable
for general fluid flow analysis. Representing the solution of the derived harmonic
wave equation by a normalized state function is quite useful in generating the properly
normalized wave functions and in the efficient evaluation of expectation values of
many operators that can be fundamental to the analysis of fluid flow especially at
the microscopic level. (author)$$$$
Temporally coherent x-ray laser with the high order harmonic light 246 KB - http://www.iaea.org/inis/collection/NCLCollectionStore/_Public/37/005/37005808.pdf - Text Version by Hasegawa, Noboru; Kawachi, Tetsuya; Kishimoto, Maki; Sukegawa, Kouta; Tanaka, Momoko;
Ochi, Yoshihiro; Nishikino, Masaharu; Kawazome, Hayato; Nagashima, Keisuke (Japan
Atomic Energy Research Inst., Kansai Research Establishment, Kizu, Kyoto (Japan)) fromProceedings of the 6th symposium on advanced photon research Read MoreCollapse
[en]
We obtained the neon-like manganese x-ray laser with the injection of the high order
harmonic light as the seed x-ray at the wavelength of 26.9 nm for the purpose of generation
of the temporally coherent x-ray laser. The x-ray amplifier, which has quite narrow
spectral width, selected and amplified the temporally coherent mode of the harmonic
light. The temporal coherence of the mode selected harmonic light was nearly transform
limited pulse, and the obtained x-ray laser with the seed x-ray expected to be nearly
temporally coherent x-ray. (author)$$$$
Spatially resolved determination of solar cell parameters is beneficial for loss analysis
and optimization of conversion efficiency. One key parameter that has been challenging
to access by an imaging technique on solar cell level is short-circuit current density.
This work discusses the robustness of a recently suggested approach to determine short-circuit
current density spatially resolved based on a series of lock-in thermography images
and options for a simplified image acquisition procedure. For an accurate result,
one or two emissivity-corrected illuminated lock-in thermography images and one dark
lock-in thermography image have to be recorded. The dark lock-in thermography image
can be omitted if local shunts are negligible. Furthermore, it is shown that omitting
the correction of lock-in thermography images for local emissivity variations only
leads to minor distortions for standard silicon solar cells. Hence, adequate acquisition
of one image only is sufficient to generate a meaningful map of short-circuit current
density. Beyond that, this work illustrates the underlying physics of the recently
proposed method and demonstrates its robustness concerning varying excitation conditions
and locally increased series resistance. Experimentally gained short-circuit current
density images are validated for monochromatic illumination in comparison to the reference
method of light-beam induced current$$$$