5,233 research outputs found
Optical Maser Emission from Trivalent Praseodymium in Calcium Tungstate
Coherent emission at 1.047 µ from trivalent praseodymium in calcium tungstate was observed. This emission coincides with strong infrared fluorescence at the same wavelength and was found to be stimulated mostly by absorption of blue light by the 3P0, 3P1, and 3P2 bands. The emission corresponds to a 1G4-->3H4 transition with the terminal level 377 cm^–1 from the ground state. The oscillation threshold was the same at 4.2°, 20°, and 78°K. No stimulated emission was observed at room temperature. The lifetime of the metastable state 1G4 is 50×10^–3 sec. A new technique used to measure the lifetime is described
Calcium Niobate Ca(NbO3)2—A New Laser Host Crystal
Large single crystals of calcium niobate Ca(NbO3)2, grown by the zochralski technique, are transparent and can be doped with rare earth or transition metal ions. Laser action has been observed in calcium niobate doped with trivalent neodymium, holmium, praseodymium, erbium, and thulium
Strong field effects on physics processes at the Interaction Point of future linear colliders
Future lepton colliders will be precision machines whose physics program
includes close study of the Higgs sector and searches for new physics via
polarised beams. The luminosity requirements of such machines entail very
intense lepton bunches at the interaction point with associated strong
electromagnetic fields. These strong fields not only lead to obvious phenomena
such as beamstrahlung, but also potentially affect every particle physics
process via virtual exchange with the bunch fields. For precision studies,
strong field effects have to be understood to the sub-percent level. Strong
external field effects can be taken into account exactly via the Furry Picture
or, in certain limits, via the Quasi-classical Operator method . Significant
theoretical development is in progress and here we outline the current state of
play.Comment: 6 pages, ICHEP 2012 Proceeding
Propagation and stability of optical pulses in a diffractive dispersive non-linear medium
Propagation and stability of light pulses under the combined influence of the optical Kerr effect, dispersion and diffraction are investigated by adopting a variational procedure. In particular, it is found that 'light bullets', i.e. radially symmetric pulses propagating without distortion, are not necessarily unstable under perturbations which do not maintain radial symmetry
Spin induced multipole moments for the gravitational wave flux from binary inspirals to third Post-Newtonian order
Using effective field theory techniques we calculate the source multipole
moments needed to obtain the spin contributions to the power radiated in
gravitational waves from inspiralling compact binaries to third Post-Newtonian
order (3PN). The multipoles depend linearly and quadratically on the spins and
include both spin(1)spin(2) and spin(1)spin(1) components. The results in this
paper provide the last missing ingredient required to determine the phase
evolution to 3PN including all spin effects which we will report in a separate
paper.Comment: 35 pages, 7 figures. Published versio
Condensates induced by interband coupling in a double-well lattice
We predict novel inter-band physics for bosons in a double-well lattice. An
intrinsic coupling between the s and px band due to interaction gives rise to
larger Mott regions on the phase diagram at even fillings than the ones at odd
fillings. On the other hand, the ground state can form various types of
condensates, including a mixture of single-particle condensates of both bands,
a mixture of a single-particle condensate of one band and a pair-condensate of
the other band, and a pair-condensate composed of one particle from one band
and one hole from the other band. The predicted phenomena should be observable
in current experiments on double-well optical lattices.Comment: Published versio
Copper and Barium Abundances in the Ursa Major Moving Group
We present Cu and Ba abundances for 7 G-K dwarf stars, members of the
solar-metallicity, 0.3 Gyr old Ursa Major Moving Group. All analyzed member
stars show [Ba/Fe] excesses of +0.3-plus, associated with [Cu/Fe] deficiencies
of up to -0.23 dex. The present results suggest that there is an
anti-correlation between the abundances of Cu and the heavy elements produced
by the main component of the neutron capture s-process. Other possible
anomalies are Na and C deficiencies with respect to normal solar-metallicity
stars. The new data do not confirm the recent claim that the group member
HR6094 is a Ba dwarf star.Comment: 8 pages, 6 figures, accepted to MNRA
Built-in reduction of statistical fluctuations of partitioning objects
Our theoretical and numerical investigation of the movement of an object that partitions a microtubule filled with small particles indicates that vibrations warranted by thermal equilibrium are reached only after a time that increases exponentially with the number of particles involved. This points to a basic mechanical process capable of breaching, on accessible time scales, the ultimate ergodic constraints that force randomness on bound microscale and nanoscale systems
Randomized benchmarking of atomic qubits in an optical lattice
We perform randomized benchmarking on neutral atomic quantum bits (qubits)
confined in an optical lattice. Single qubit gates are implemented using
microwaves, resulting in a measured error per randomized computational gate of
1.4(1) x 10^-4 that is dominated by the system T2 relaxation time. The results
demonstrate the robustness of the system, and its viability for more advanced
quantum information protocols.Comment: 11 pages, 4 figure
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