129,158 research outputs found
Segue Between Favorable and Unfavorable Solvation
Solvation of small and large clusters are studied by simulation, considering
a range of solvent-solute attractive energy strengths. Over a wide range of
conditions, both for solvation in the Lennard-Jones liquid and in the SPC model
of water, it is shown that the mean solvent density varies linearly with
changes in solvent-solute adhesion or attractive energy strength. This behavior
is understood from the perspective of Weeks' theory of solvation [Ann. Rev.
Phys. Chem. 2002, 53, 533] and supports theories based upon that perspective.Comment: 8 pages, 7 figure
Resonant elastic soft x-ray scattering in oxygen-ordered YBa_2Cu_3O_{6+delta}
Static charge-density wave (CDW) and spin-density wave (SDW) order has been
convincingly observed in La-based cuprates for some time. However, more
recently it has been suggested by quantum oscillation, transport and
thermodynamic measurements that density wave order is generic to underdoped
cuprates and plays a significant role in YBa_2Cu_3O_{6+delta} (YBCO). We use
resonant soft x-ray scattering at the Cu L and O K edges to search for evidence
of density wave order in Ortho-II and Ortho-VIII oxygen-ordered YBCO. We report
a null result -- no evidence for static CDW order -- in both Ortho-II and
Ortho-VIII ordered YBCO. While this does not rule out static CDW order in the
CuO_2 planes of YBCO, these measurements place limits on the parameter space
(temperature, magnetic field, scattering vector) in which static CDW order may
exist. In addition, we present a detailed analysis of the energy and
polarization dependence of the Ortho-II superstructure Bragg reflection [0.5 0
0] at the Cu L edge. The intensity of this peak, which is due to the valence
modulations of Cu in the chain layer, is compared with calculations using
atomic scattering form factors deduced from x-ray absorption measurements. The
calculated energy and polarization dependence of the scattering intensity is
shown to agree very well with the measurement, validating the approach and
providing a framework for analyzing future resonant soft x-ray scattering
measurements.Comment: 11 pages, 9 figure
Analysis and interpretation of high transverse entanglement in optical parametric down conversion
Quantum entanglement associated with transverse wave vectors of down
conversion photons is investigated based on the Schmidt decomposition method.
We show that transverse entanglement involves two variables: orbital angular
momentum and transverse frequency. We show that in the monochromatic limit high
values of entanglement are closely controlled by a single parameter resulting
from the competition between (transverse) momentum conservation and
longitudinal phase matching. We examine the features of the Schmidt eigenmodes,
and indicate how entanglement can be enhanced by suitable mode selection
methods.Comment: 4 pages, 4 figure
- …