81,745 research outputs found
Nonlinear Young integrals via fractional calculus
For H\"older continuous functions and , we define
nonlinear integral via fractional calculus. This
nonlinear integral arises naturally in the Feynman-Kac formula for stochastic
heat equations with random coefficients. We also define iterated nonlinear
integrals.Comment: arXiv admin note: substantial text overlap with arXiv:1404.758
Series of broad resonances in atomic three-body systems
We re-examine the series of resonances found earlier in atomic three-body
systems by solving the Faddeev-Merkuriev integral equations. These resonances
are rather broad and line-up at each threshold with gradually increasing gaps,
the same way for all thresholds and irrespective of the spatial symmetry. We
relate these resonances to the Gailitis mechanism, which is a consequence of
the polarization potential.Comment: 14 pages, 7 figures. arXiv admin note: text overlap with
arXiv:0810.303
Exceptional Points in a Non-Hermitian Topological Pump
We investigate the effects of non-Hermiticity on topological pumping, and
uncover a connection between a topological edge invariant based on topological
pumping and the winding numbers of exceptional points. In Hermitian lattices,
it is known that the topologically nontrivial regime of the topological pump
only arises in the infinite-system limit. In finite non-Hermitian lattices,
however, topologically nontrivial behavior can also appear. We show that this
can be understood in terms of the effects of encircling a pair of exceptional
points during a pumping cycle. This phenomenon is observed experimentally, in a
non-Hermitian microwave network containing variable gain amplifiers.Comment: 7 pages, 7 figures. The first author did the experiment, and the
second author did the theoretical stud
Enhanced flux pinning in YBa2Cu3O7-d films by nano-scaled substrate surface roughness
Nano-scaled substrate surface roughness is shown to strongly influence the
critical current density Jc in YBCO films made by pulse-laser-deposition on the
crystalline LaAlO3 substrates consisting of two separate twin-free and
twin-rich regions. The nano-scaled corrugated surface was created in the
twin-rich region during the deposition process. Using magneto-optical imaging
techniques coupled with optical and atomic force microscopy, we observed an
enhanced flux pinning in the YBCO films in the twin-rich region, resulted in
\~30% increase in Jc, which was unambiguously confirmed by the direct transport
measurement.Comment: 16 pages, 3 figures, accepted by Applied Physics Letter
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