1,926 research outputs found
Spin-orbit driven Peierls transition and possible exotic superconductivity in CsWO
We study \textit{ab initio} a pyrochlore compound, CsWO, which
exhibits a yet unexplained metal-insulator transition. We find that (1) the
reported low- structure is likely inaccurate and the correct structure has a
twice larger cell; (2) the insulating phase is not of a Mott or dimer-singlet
nature, but a rare example of a 3D Peierls transition, with a simultaneous
condensation of three density waves; (3) spin-orbit interaction plays a crucial
role, forming well-nested bands. The high- (HT) phase, if stabilized, could
harbor a unique superconducting state that breaks the time
reversal symmetry, but is not chiral. This state was predicted in 1999, but
never observed. We speculate about possible ways to stabilize the HT phase
while keeping the conditions for superconductivity
Security of coherent state quantum cryptography in the presence of Gaussian noise
We investigate the security against collective attacks of a continuous
variable quantum key distribution scheme in the asymptotic key limit for a
realistic setting. The quantum channel connecting the two honest parties is
assumed to be lossy and imposes Gaussian noise on the observed quadrature
distributions. Secret key rates are given for direct and reverse reconciliation
schemes including postselection in the collective attack scenario. The effect
of a non-ideal error correction and two-way communication in the classical
post-processing step is also taken into account.Comment: 12 pages, 5 figures updated version including two-way communication;
changed the definition of the excess noise to match the definition given
earlier (Phys. Rev. Lett. 92, 117901); submitted to PRA; presented at the 8th
International Conference on Quantum Communication, Measurement and Computing,
Tsukub
Selecting Design Professionals for Public Library Construction
Creating a dynamic building team for a public library construction project is essential to its success. This article outlines the process and includes points to consider for the Request for Proposal for design professionals, a checklist and interview questions to serve as a guide
Spotlight on Construction: Planning, Communication Are Key in Building New Libraries
The article presents an outline for beginning the process of building new library for the community based on planning principles that will lead to a well-documented and articulated plan for the future. The development of a comprehensive strategic plan of library service is the first step a library system should take. The Public Library Association (PLA) New Planning for Results, which has been used successfully by many libraries in the U.S. is one example of a successful planning model. The final step in the process is writing a building program
The Role of the Library Board of Trustees in the Construction of a Public Library
The article presents information on areas where the library board of trustees may have a direct role in the construction of a public library in the U.S. It notes that board members are as necessary to the design and construction of a library as are the library director, administration staff, the architect, interior design professional, general contractor and project manager of the construction project. The board is expected to conduct a Facilities Master Plan study for the library system before seeking funding for any project. It also enumerates the responsibilities the library board members must approve during the entire construction project
Leadership, Libraries, LEED for the Future
The article discusses the use of Leadership in Energy and Environmental Design (LEED) principles in the design of the modern public library. It is stated that an LEED-certified library will have lower costs in energy, systems replacement and maintenance through the use of light-emitting diode (LED) lighting and efficient heating and air conditioning, but that due to special materials, the up-front expense is higher. The inspection of the facility throughout its construction is also noted
Phonon dispersion and electron-phonon coupling in MgB_2 and AlB_2
We present a first principles investigation of the lattice dynamics and
electron-phonon coupling of the superconductor MgB_2 and the isostructural
AlB_2 within the framework of density functional perturbation theory using a
mixed-basis pseudopotential method. Complete phonon dispersion curves and
Eliashberg functions \alpha^2F are calculated for both systems. We also report
on Raman measurements, which support the theoretical findings. The calculated
generalized density-of-states for MgB_2 is in excellent agreement with recent
neutron-scattering experiments. The main differences in the calculated phonon
spectra and \alpha^2F are related to high frequency in-plane boron vibrations.
As compared to AlB_2, they are strongly softened in MgB_2 and exhibit an
exceptionally strong coupling to electronic states at the Fermi energy. The
total coupling constants are \lambda_{MgB_2}=0.73 and \lambda_{AlB_2}=0.43.
Implications for the superconducting transition temperature are briefly
discussed.Comment: 10 pages, 4 figures, to appear in Phys. Rev. Let
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