579 research outputs found
Academic Landscape Based on Network Analysis Considering Analysis of Variation in the Years of Lucubration Publishing
Correlated electron transport through double quantum dots coupled to normal and superconducting leads
We study Andreev transport through double quantum dots connected in series
normal and superconducting (SC) leads, using the numerical renormalization
group. The ground state of this system shows a crossover between a local
Cooper-pairing singlet state and a Kondo singlet state, which is caused by the
competition between the Coulomb interaction and the SC proximity. We show that
the ground-state properties reflect this crossover especially for small values
of the inter-dot coupling , while in the opposite case, for large ,
another singlet with an inter-dot character becomes dominant. We find that the
conductance for the local SC singlet state has a peak with the unitary-limit
value . In contrast, the Andreev reflection is suppressed in the Kondo
regime by the Coulomb interaction. Furthermore, the conductance has two
successive peaks in the transient region of the crossover. It is further
elucidated that the gate voltage gives a different variation into the
crossover. Specifically, as the energy level of the dot that is coupled to the
normal lead varies, the Kondo screening cloud is deformed to a long-range
singlet bond.Comment: 11 pages, 10 figure
Study on Seismic Retrofit Planning Method for Seweage Treatment Plants on the Basis of Seismic Risk Management
Japanese sewerage has more than 100 years of history, and many facilities have passed their durable years. For the sake of economy, life lengthening of the equipment and facilities is required. Rational life extension of the equipment and facilities calls for aseismic reinforcement of structures with damage risks considered. Based on this, the author et al. suggested a method that will help planning rational aseismic reinforcement for sewage treatment plants. This method quantitatively evaluates the relationship between the earthquake risk and aseismic reinforcement cost by introducing the concept of risk management. In this study, availability of this method also has been verified with exemplification
Asymptotic behavior of dynamical variables and naked singularity formation in spherically symmetric gravitational collapse
Considering gravitational collapse of matter, it is important problem to
clarify what kind of conditions leads to the formation of naked singularity.
For this purpose, we apply the 1+3 orthonormal frame formalism introduced by
Uggla \textit{et al.} to spherically symmetric gravitational collapse of
perfect fluid. This formalism allows us to construct an autonomous system of
evolution and constraint equations for scale-invariant dynamical variables
normalized by the volume expansion rate of the timelike orthonormal frame
vector. We investigate the asymptotic evolution of such dynamical variables
towards the formation of a central singularity and present a conjecture that
the steep spatial gradient for the normalized density function is a
characteristic of the naked singularity formation.Comment: Version published in PR
Quantum crossover in moderately damped epitaxial NbN/MgO/NbN junctions with low critical current density
High quality epitaxial NbN/MgO/NbN Josephson junctions have been realized
with MgO barriers up to a thickness of d=1 nm. The junction properties
coherently scale with the size of barrier, and low critical current densities
down to 3 A/cm have been achieved for larger barriers. In this limit,
junctions exhibit macroscopic quantum phenomena for temperatures lower than 90
mK. Measurements and junction parameters support the notion of a possible use
of these devices for multiphoton quantum experiments, taking advantage of the
fast non equilibrium electron-phonon relaxation times of NbN
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