33,230 research outputs found
Group theoretical study of LOCC-detection of maximally entangled state using hypothesis testing
In the asymptotic setting, the optimal test for hypotheses testing of the
maximally entangled state is derived under several locality conditions for
measurements. The optimal test is obtained in several cases with the asymptotic
framework as well as the finite-sample framework. In addition, the experimental
scheme for the optimal test is presented
Investigation of environmental change pattern in Japan. Observation of present state of agricultural land-use by analysing LANDSAT data
The author has identified the following significant results. Species and ages of grasses in pastures were identified, and soils were classified into several types using LANDSAT data. This data could be used in a wide area of cultivation, reclamation, or management planning on agricultural land
Structure and Stability of Magnetic Fields in Solar Active Region12192 Based on Nonlinear Force-Free Field Modeling
We analyze a three-dimensional (3D) magnetic structure and its stability in
large solar active region(AR) 12192, using the 3D coronal magnetic field
constructed under a nonlinear force-free field (NLFFF) approximation. In
particular, we focus on the magnetic structure that produced an X3.1-class
flare which is one of the X-class flares observed in AR 12192. According to our
analysis, the AR contains multiple-flux-tube system, {\it e.g.}, a large flux
tube, both of whose footpoints are anchored to the large bipole field, under
which other tubes exist close to a polarity inversion line (PIL). These various
flux tubes of different sizes and shapes coexist there. In particular, the
later are embedded along the PIL, which produces a favorable shape for the
tether-cutting reconnection and is related to the X-class solar flare. We
further found that most of magnetic twists are not released even after the
flare, which is consistent with the fact that no observational evidence for
major eruptions was found. On the other hand, the upper part of the flux tube
is beyond a critical decay index, essential for the excitation of torus
instability before the flare, even though no coronal mass ejections (CMEs) were
observed. We discuss the stability of the complicated flux tube system and
suggest the reason for the existence of the stable flux tube. In addition, we
further point out a possibility for tracing the shape of flare ribbons, on the
basis of a detailed structural analysis of the NLFFF before a flare.Comment: 24 pages, 9 figures, accepted for publication in The Astrophysical
Journa
Curvature and topological effects on dynamical symmetry breaking in a four- and eight-fermion interaction model
A dynamical mechanism for symmetry breaking is investigated under the
circumstances with the finite curvature, finite size and non-trivial topology.
A four- and eight-fermion interaction model is considered as a prototype model
which induces symmetry breaking at GUT era. Evaluating the effective potential
in the leading order of the 1/N-expansion by using the dimensional
regularization, we explicitly calculate the phase boundary which divides the
symmetric and the broken phase in a weakly curved space-time and a flat
space-time with non-trivial topology, .Comment: 20 pages, 21 figure
Error Exponent in Asymmetric Quantum Hypothesis Testing and Its Application to Classical-Quantum Channel coding
In the simple quantum hypothesis testing problem, upper bound with asymmetric
setting is shown by using a quite useful inequality by Audenaert et al,
quant-ph/0610027, which was originally invented for symmetric setting. Using
this upper bound, we obtain the Hoeffding bound, which are identical with the
classical counter part if the hypotheses, composed of two density operators,
are mutually commutative. Our upper bound improves the bound by Ogawa-Hayashi,
and also provides a simpler proof of the direct part of the quantum Stein's
lemma. Further, using this bound, we obtain a better exponential upper bound of
the average error probability of classical-quantum channel coding
Electrical pump-and-probe study of spin singlet-triplet relaxation in a quantum dot
Spin relaxation from a triplet excited state to a singlet ground state in a
semiconductor quantum dot is studied by employing an electrical pump-and-probe
method. Spin relaxation occurs via cotunneling when the tunneling rate is
relatively large, confirmed by a characteristic square dependence of the
relaxation rate on the tunneling rate. When cotunneling is suppressed by
reducing the tunneling rate, the intrinsic spin relaxation is dominated by
spin-orbit interaction. We discuss a selection rule of the spin-orbit
interaction based on the observed double-exponential decay of the triplet
state.Comment: 4 pages, 4 figure
General Scheme for Perfect Quantum Network Coding with Free Classical Communication
This paper considers the problem of efficiently transmitting quantum states
through a network. It has been known for some time that without additional
assumptions it is impossible to achieve this task perfectly in general --
indeed, it is impossible even for the simple butterfly network. As additional
resource we allow free classical communication between any pair of network
nodes. It is shown that perfect quantum network coding is achievable in this
model whenever classical network coding is possible over the same network when
replacing all quantum capacities by classical capacities. More precisely, it is
proved that perfect quantum network coding using free classical communication
is possible over a network with source-target pairs if there exists a
classical linear (or even vector linear) coding scheme over a finite ring. Our
proof is constructive in that we give explicit quantum coding operations for
each network node. This paper also gives an upper bound on the number of
classical communication required in terms of , the maximal fan-in of any
network node, and the size of the network.Comment: 12 pages, 2 figures, generalizes some of the results in
arXiv:0902.1299 to the k-pair problem and codes over rings. Appeared in the
Proceedings of the 36th International Colloquium on Automata, Languages and
Programming (ICALP'09), LNCS 5555, pp. 622-633, 200
Composite-type Rb-87 optical-pumping light source for the rubidium frequency standard
The light source is composed of a cylindrical Rb-87 lamp 10 mm diameter and a Rb-85 filter cell 3-7 mm long attached to the front flat face of the lamp. This composite type device is operated in an oven at about 100 C. Thus a light source for Rb-87 hyperfine optical pumping less than 4 cm long by 3 cm diameter was constructed
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