15,888 research outputs found
Precise timing correlation in telemetry recording and processing systems
Independent PCM telemetry data signals received from missiles must be correlated to within + or - 100 microseconds for comparison with radar data. Tests have been conducted to determine RF antenna receiving system delays; delays associated with wideband analog tape recorders used in the recording, dubbing and repdocuing processes; and uncertainties associated with computer processed time tag data. Several methods used in the recording of timing are evaluated. Through the application of a special time tagging technique, the cumulative timing bias from all sources is determined and the bias removed from final data. Conclusions show that relative time differences in receiving, recording, playback and processing of two telemetry links can be accomplished with a + or - 4 microseconds accuracy. In addition, the absolute time tag error (with respect to UTC) can be reduced to less than 15 microseconds. This investigation is believed to be the first attempt to identify the individual error contributions within the telemetry system and to describe the methods of error reduction within the telemetry system and to describe the methods of error reduction and correction
Heralding two- and four-photon path entanglement on chip
Generating quantum entanglement is not only an important scientific endeavor,
but will be essential to realizing quantum-enhanced technologies, in
particular, quantum-enhanced measurements with precision beyond classical
limits. We investigate the heralded generation of multiphoton entanglement for
quantum metrology using a reconfigurable integrated waveguide device in which
projective measurement of auxiliary photons heralds the generation of
path-entangled states. We use four and six-photon inputs, to analyze the
heralding process of two- and four-photon NOON states-a superposition of N
photons in two paths, capable of enabling phase supersensitive measurements at
the Heisenberg limit. Realistic devices will include imperfections; as part of
the heralded state preparation, we demonstrate phase superresolution within our
chip with a state that is more robust to photon loss
The 2013 February 17 sunquake in the context of the active region's magnetic field configuration
© 2017. The American Astronomical Society. All rights reserved. Sunquakes are created by the hydrodynamic response of the lower atmosphere to a sudden deposition of energy and momentum. In this study, we investigate a sunquake that occurred in NOAA active region 11675 on 2013 February 17. Observations of the corona, chromosphere, and photosphere are brought together for the first time with a nonlinear force-free model of the active region's magnetic field in order to probe the magnetic environment in which the sunquake was initiated. We find that the sunquake was associated with the destabilization of a flux rope and an associated M-class GOES flare. Active region 11675 was in its emergence phase at the time of the sunquake and photospheric motions caused by the emergence heavily modified the flux rope and its associated quasi-separatrix layers, eventually triggering the flux rope's instability. The flux rope was surrounded by an extended envelope of field lines rooted in a small area at the approximate position of the sunquake. We argue that the configuration of the envelope, by interacting with the expanding flux rope, created a “magnetic lens” that may have focussed energy on one particular location of the photosphere, creating the necessary conditions for the initiation of the sunquake
Shor's quantum factoring algorithm on a photonic chip
Shor's quantum factoring algorithm finds the prime factors of a large number
exponentially faster than any other known method a task that lies at the heart
of modern information security, particularly on the internet. This algorithm
requires a quantum computer a device which harnesses the `massive parallelism'
afforded by quantum superposition and entanglement of quantum bits (or qubits).
We report the demonstration of a compiled version of Shor's algorithm on an
integrated waveguide silica-on-silicon chip that guides four single-photon
qubits through the computation to factor 15.Comment: 2 pages, 1 figur
Delayed payment of federal estate taxes (1986)
Farmers and small-business owners often fear that their loved ones might have to sell the family business to pay death taxes. In reality, the probability of a forced sale solely to pay estate taxes is small for three reasons.New 8/86/8M
Quantum-enhanced phase estimation using optical spin squeezing
Quantum metrology enables estimation of optical phase shifts with precision
beyond the shot-noise limit. One way to exceed this limit is to use squeezed
states, where the quantum noise of one observable is reduced at the expense of
increased quantum noise for its complementary partner. Because shot-noise
limits the phase sensitivity of all classical states, reduced noise in the
average value for the observable being measured allows for improved phase
sensitivity. However, additional phase sensitivity can be achieved using phase
estimation strategies that account for the full distribution of measurement
outcomes. Here we experimentally investigate the phase sensitivity of a
five-particle optical spin-squeezed state generated by photon subtraction from
a parametric downconversion photon source. The Fisher information for all
photon-number outcomes shows it is possible to obtain a quantum advantage of
1.58 compared to the shot-noise limit, even though due to experimental
imperfection, the average noise for the relevant spin-observable does not
achieve sub-shot-noise precision. Our demonstration implies improved
performance of spin squeezing for applications to quantum metrology.Comment: 8 pages, 5 figure
Estate planning for Missouri families (1982)
"February 1982""It has been said that one of the blessings of life is that people never know how long it will last. Most people were better prepared for birth, of which they could do nothing, than for death or taxes, of which they can do a great deal. While is an unpleasant subject, it is inevitable. An estate plan will not enable you to avoid death or taxes -- but it does allow preparation for them and lessens their impact on surviving family members. When a person dies, his estate does not disappear with him. It remains behind to be distributed by someone. If a person does not provide a workable transfer plan for the courts to follow upon his death, the estate will be distributed according to state statutes."--First page.Ronald L. Plain (Assistant Professor of Agricultural Economics and Extension Farm Management Specialist), Stephen F. Matthews (Associate Professor of Agricultural Economics and Member of the Missouri Bar
Coherent Time Evolution and Boundary Conditions of Two-Photon Quantum Walks
Multi-photon quantum walks in integrated optics are an attractive controlled
quantum system, that can mimic less readily accessible quantum systems and
exhibit behavior that cannot in general be accurately replicated by classical
light without an exponential overhead in resources. The ability to observe time
evolution of such systems is important for characterising multi-particle
quantum dynamics---notably this includes the effects of boundary conditions for
walks in spaces of finite size. Here we demonstrate the coherent evolution of
quantum walks of two indistinguishable photons using planar arrays of 21
evanescently coupled waveguides fabricated in silicon oxynitride technology. We
compare three time evolutions, that follow closely a model assuming unitary
evolution, corresponding to three different lengths of the array---in each case
we observe quantum interference features that violate classical predictions.
The longest array includes reflecting boundary conditions.Comment: 7 pages,7 figure
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