7,199 research outputs found
Beyond the hybrid library : libraries in a Web 2.0 world
Considers the development of social networking and the concept of Web 2.0. Looks at the implications for libraries and how traditional competences remain relevant. Explores what libraries are doing and must do to remain relevan
Magnetic order in the quasi-one-dimensional spin 1/2 chain, copper pyrazine dinitrate
We present the first evidence of magnetic order in the quasi-one-dimensional
spin 1/2 molecular chain compound, copper pyrazine dinitrate Cu(C4H4N2)(NO3)2}.
Zero field muon-spin relaxation measurements made at dilution refrigerator
temperatures show oscillations in the measured asymmetry, characteristic of a
quasistatic magnetic field at the muon sites. Our measurements provide
convincing evidence for long range magnetic order below a temperature
T_N=107(1) mK. This leads to an estimate of the interchain coupling constant of
|J'|/k_B=0.046 K and to a ratio |J'/J| = 4.4 x 10^-3.Comment: 4 pages, 3 figures. Submitted to Physical Review Letter
Effect of magnesium doping on the orbital and magnetic order in LiNiO2
In LiNiO2, the Ni3+ ions, with S=1/2 and twofold orbital degeneracy, are
arranged on a trian- gular lattice. Using muon spin relaxation (MuSR) and
electron spin resonance (ESR), we show that magnesium doping does not stabilize
any magnetic or orbital order, despite the absence of interplane Ni2+. A
disordered, slowly fluctuating state develops below 12 K. In addition, we find
that magnons are excited on the time scale of the ESR experiment. At the same
time, a g factor anisotropy is observed, in agreement with
orbital occupancy
Manifestations of quantum holonomy in interferometry
Abelian and non-Abelian geometric phases, known as quantum holonomies, have
attracted considerable attention in the past. Here, we show that it is possible
to associate nonequivalent holonomies to discrete sequences of subspaces in a
Hilbert space. We consider two such holonomies that arise naturally in
interferometer settings. For sequences approximating smooth paths in the base
(Grassmann) manifold, these holonomies both approach the standard holonomy. In
the one-dimensional case the two types of holonomies are Abelian and coincide
with Pancharatnam's geometric phase factor. The theory is illustrated with a
model example of projective measurements involving angular momentum coherent
states.Comment: Some changes, journal reference adde
Ethics beyond the code of conduct - understanding the ethical dilemmas of entrepreneurs
Entrepreneurs choose a particular way of life with the dual aim of maximising profit and gaining a sense of self-satisfaction. In these endeavours, entrepreneurs typically live with the threat of competition and the risk of business failure, while attempting to do their best within the limitations of their resources. This qualitative study first examines existing theories of ethics and ways of applying business ethics and thereafter investigates entrepreneurs' actual experiences by means of in-depth interviews and the use of phenomenology. It finds that entrepreneurs are not guided by any specific code of conduct, and must decide for themselves what is right. It describes the entrepreneurial business ethic, some of the types of dilemmas that they experience and the methods that they have developed to deal with the dilemmas
Isotope effect in quasi-two-dimensional metal-organic antiferromagnets
Although the isotope effect in superconducting materials is well-documented,
changes in the magnetic properties of antiferromagnets due to isotopic
substitution are seldom discussed and remain poorly understood. This is perhaps
surprising given the possible link between the quasi-two-dimensional (Q2D)
antiferromagnetic and superconducting phases of the layered cuprates. Here we
report the experimental observation of shifts in the N\'{e}el temperature and
critical magnetic fields (; ) in a Q2D organic molecular antiferromagnets on
substitution of hydrogen for deuterium. These compounds are characterized by
strong hydrogen bonds through which the dominant superexchange is mediated. We
evaluate how the in-plane and inter-plane exchange energies evolve as the
hydrogens on different ligands are substituted, and suggest a possible
mechanism for this effect in terms of the relative exchange efficiency of
hydrogen and deuterium bonds
Economical (k,m)-threshold controlled quantum teleportation
We study a (k,m)-threshold controlling scheme for controlled quantum
teleportation. A standard polynomial coding over GF(p) with prime p > m-1 needs
to distribute a d-dimensional qudit with d >= p to each controller for this
purpose. We propose a scheme using m qubits (two-dimensional qudits) for the
controllers' portion, following a discussion on the benefit of a quantum
control in comparison to a classical control of a quantum teleportation.Comment: 11 pages, 2 figures, v2: minor revision, discussions improved, an
equation corrected in procedure (A) of section 4.3, v3: major revision,
protocols extended, citations added, v4: minor grammatical revision, v5:
minor revision, discussions extende
Precision measurement and compensation of optical Stark shifts for an ion-trap quantum processor
Using optical Ramsey interferometry, we precisely measure the laser-induced
AC-stark shift on the -- "quantum bit" transition near 729
nm in a single trapped Ca ion. We cancel this shift using an
additional laser field. This technique is of particular importance for the
implementation of quantum information processing with cold trapped ions. As a
simple application we measure the atomic phase evolution during a rotation of the quantum bit.Comment: 4 pages, 4 figure
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