9,370 research outputs found
Multi-neutron transfer coupling in sub-barrier 32S+90,96Zr fusion reactions
The role of neutron transfers is investigated in the fusion process below the
Coulomb barrier by analyzing 32S+90Zr and 32S+96Zr as benchmark reactions. A
full coupled-channel calculation of the fusion excitation functions has been
performed for both systems by using multi-neutron transfer coupling for the
more neutron-rich reaction. The enhancement of fusion cross sections for
32S+96Zr is well reproduced at sub-barrier energies by NTFus code calculations
including the coupling of the neutron-transfer channels following the Zagrebaev
semiclassical model. We found similar effects for 40Ca+90Zr and 40Ca+96Zr
fusion excitation functions.Comment: Minor corrections, 11 pages, 4 figures, Fusion11 Conference, Saint
Malo, France, 2-6 mai 201
On the Convergence of Ritz Pairs and Refined Ritz Vectors for Quadratic Eigenvalue Problems
For a given subspace, the Rayleigh-Ritz method projects the large quadratic
eigenvalue problem (QEP) onto it and produces a small sized dense QEP. Similar
to the Rayleigh-Ritz method for the linear eigenvalue problem, the
Rayleigh-Ritz method defines the Ritz values and the Ritz vectors of the QEP
with respect to the projection subspace. We analyze the convergence of the
method when the angle between the subspace and the desired eigenvector
converges to zero. We prove that there is a Ritz value that converges to the
desired eigenvalue unconditionally but the Ritz vector converges conditionally
and may fail to converge. To remedy the drawback of possible non-convergence of
the Ritz vector, we propose a refined Ritz vector that is mathematically
different from the Ritz vector and is proved to converge unconditionally. We
construct examples to illustrate our theory.Comment: 20 page
Structural and spectral dynamics of single-crystalline Ruddlesden-Popper phase halide perovskite blue light-emitting diodes.
Achieving perovskite-based high-color purity blue-emitting light-emitting diodes (LEDs) is still challenging. Here, we report successful synthesis of a series of blue-emissive two-dimensional Ruddlesden-Popper phase single crystals and their high-color purity blue-emitting LED demonstrations. Although this approach successfully achieves a series of bandgap emissions based on the different layer thicknesses, it still suffers from a conventional temperature-induced device degradation mechanism during high-voltage operations. To understand the underlying mechanism, we further elucidate temperature-induced device degradation by investigating the crystal structural and spectral evolution dynamics via in situ temperature-dependent single-crystal x-ray diffraction, photoluminescence (PL) characterization, and density functional theory calculation. The PL peak becomes asymmetrically broadened with a marked intensity decay, as temperature increases owing to [PbBr6]4- octahedra tilting and the organic chain disordering, which results in bandgap decrease. This study indicates that careful heat management under LED operation is a key factor to maintain the sharp and intense emission
Spin entanglement induced by spin-orbit interactions in coupled quantum dots
We theoretically explore the possibility of creating spin quantum
entanglement in a system of two electrons confined respectively in two
vertically coupled quantum dots in the presence of Rashba type spin-orbit
coupling. We find that the system can be described by a generalized Jaynes -
Cummings model of two modes bosons interacting with two spins. The lower
excitation states of this model are calculated to reveal the underlying physics
of the far infrared absorption spectra. The analytic perturbation approach
shows that an effective transverse coupling of spins can be obtained by
eliminating the orbital degrees of freedom in the large detuning limit. Here,
the orbital degrees of freedom of the two electrons, which are described by two
modes of bosons, serve as a quantized data bus to exchange the quantum
information between two electrons. Then a nontrivial two-qubit logic gate is
realized and spin entanglement between the two electrons is created by virtue
of spin-orbit coupling.Comment: 7 pages, 5 figure
An extended fault-tolerant link-state routing protocol in the internet
2003-2004 > Academic research: refereed > Publication in refereed journalVersion of RecordPublishe
Climate and Livelihoods in Rural Ningxia: Final Report. The Impacts of Climate Change on Chinese Agriculture - Phase II National Level Study final report
A Dual-Polarized Linear Antenna Array with Improved Isolation Using A Slotline-Based 180° Hybrid for Full-Duplex Applications
- …