1,538 research outputs found
Variable electrostatic transformer: controllable coupling of two charge qubits
We propose and investigate a novel method for the controlled coupling of two
Josephson charge qubits by means of a variable electrostatic transformer. The
value of the coupling capacitance is given by the discretized curvature of the
lowest energy band of a Josephson junction, which can be positive, negative, or
zero. We calculate the charging diagram of the two-qubit system that reflects
the transition from positive to negative through vanishing coupling. We also
discuss how to construct a phase gate making use of the controllable coupling.Comment: final version, to appear in Phys. Rev. Let
Submicrosecond comparisons of time standards via the Navigation Technology Satellites (NTS)
An interim demonstration was performed of the time transfer capability of the NAVSTAR GPS system using a single NTS satellite. Measurements of time difference (pseudo-range) are made from the NTS tracking network and at the participating observatories. The NTS network measurements are used to compute the NTS orbit trajectory. The central NTS tracking station has a time link to the Naval Observatory UTC (USNO,MC1) master clock. Measurements are used with the NTS receiver at the remote observatory, the time transfer value UTC (USNO,MC1)-UTC (REMOTE, VIA NTS) is calculated. Intercomparisons were computed using predicted values of satellite clock offset and ephemeus
Study of Space Station propulsion system resupply and repair Final report
Resupply and repair capabilities for orbital space station bipropellant propulsion syste
Thermal noise properties of two aging materials
In this lecture we review several aspects of the thermal noise properties in
two aging materials: a polymer and a colloidal glass.
The measurements have been performed after a quench for the polymer and
during the transition from a fluid-like to a solid-like state for the gel. Two
kind of noise has been measured: the electrical noise and the mechanical noise.
For both materials we have observed that the electric noise is characterized
by a strong intermittency, which induces a large violation of the Fluctuation
Dissipation Theorem (FDT) during the aging time, and may persist for several
hours at low frequency. The statistics of these intermittent signals and their
dependance on the quench speed for the polymer or on sample concentration for
the gel are studied. The results are in a qualitative agreement with recent
models of aging, that predict an intermittent dynamics. For the mechanical
noise the results are unclear. In the polymer the mechanical thermal noise is
still intermittent whereas for the gel the violation of FDT, if it exists, is
extremely small.Comment: to be published in the Proceedings of the XIX Sitges Conference on
''Jammming, Yielding and Irreversible Deformation in Condensed Matter'',
M.-C.Miguel and M. Rubi eds.,Springer Verlag, Berli
Relativistic spectroscopy of the extreme NLS1 IRAS13224-3809
The narrow line Seyfert 1 (NLS1) IRAS 13224-3809 is the most X-ray variable
active galactic nucleus (AGN), exhibiting 0.3-10 keV flux changes of over an
order of magnitude within an hour. We report on the results of the 1.5 Ms 2016
XMM-Newton/NuSTAR observing campaign, which revealed the presence of a 0.24c
ultra-fast outflow in addition to the well-known strong relativistic
reflection. We also summarise other key results of the campaign, such as the
first detection of a non-linear RMS-flux relation in an accreting source,
correlations between outflow absorption strength/velocity and source flux, and
a disconnect between the X-ray and UV emission. Our results are consistent with
a scenario where a disk wind is launched close to the black hole, imprinting
absorption features into the spectrum and variability.Comment: 6 pages, 7 figures, contributed talk at "Revisiting narrow-line
Seyfert 1 galaxies and their place in the Universe" (Padova, April 2018).
Accepted for publication in Proceedings of Science, PoS(NLS1-2018)03
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