10,667 research outputs found
The entanglement beam splitter: a quantum-dot spin in a double-sided optical microcavity
We propose an entanglement beam splitter (EBS) using a quantum-dot spin in a
double-sided optical microcavity. In contrast to the conventional optical beam
splitter, the EBS can directly split a photon-spin product state into two
constituent entangled states via transmission and reflection with high fidelity
and high efficiency (up to 100 percent). This device is based on giant optical
circular birefringence induced by a single spin as a result of cavity quantum
electrodynamics and the spin selection rule of trion transition (Pauli
blocking). The EBS is robust and it is immune to the fine structure splitting
in a realistic quantum dot. This quantum device can be used for
deterministically creating photon-spin, photon-photon and spin-spin
entanglement as well as a single-shot quantum non-demolition measurement of a
single spin. Therefore, the EBS can find wide applications in quantum
information science and technology.Comment: 7 pages, 5 figure
Capillary Action Around Dental Structures
The capillary action of saliva occurs in the crevices around and between teeth and around dental restorations. Marginal leakage and denture retention caused by a thin film of saliva are aspects of capillary phenomena. Liquids in capillaries isolated from a reservoir showed an increase in surface tension and lower vapor pressure. The strength of thin films of human saliva was independent of ambient pressure.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/67133/2/10.1177_00220345730520032801.pd
Twisted Fermi surface of a thin-film Weyl semimetal
The Fermi surface of a conventional two-dimensional electron gas is
equivalent to a circle, up to smooth deformations that preserve the orientation
of the equi-energy contour. Here we show that a Weyl semimetal confined to a
thin film with an in-plane magnetization and broken spatial inversion symmetry
can have a topologically distinct Fermi surface that is twisted into a
\mbox{figure-8} opposite orientations are coupled at a crossing which is
protected up to an exponentially small gap. The twisted spectral response to a
perpendicular magnetic field is distinct from that of a deformed Fermi
circle, because the two lobes of a \mbox{figure-8} cyclotron orbit give
opposite contributions to the Aharonov-Bohm phase. The magnetic edge channels
come in two counterpropagating types, a wide channel of width and a narrow channel of width (with
the magnetic length and the momentum separation
of the Weyl points). Only one of the two is transmitted into a metallic
contact, providing unique magnetotransport signatures.Comment: V4: 10 pages, 14 figures. Added figure and discussion about
"uncrossing deformations" of oriented contours, plus minor corrections.
Published in NJ
Color Analysis of Dental Modifying Porcelains
Sintered samples of modifying porcelains of various colors and manufacturers were analyzed using reflectance spectrophotometry. Color designations are reported according to practices of the Commission Internationale de l'Eclairage (International Commission for Illumination), and color names were assigned based on a method developed through a joint effort of the Inter-Society Color Council and the United States National Bureau of Standards (ISCC.NBS). Within samples labeled by the same color, differences among manufacturers were found in the color designations and names. These differences were noted in part by plots of the chromaticity coordinates of the samples. The ISCC-NBS method of designating colors is proposed as a uniform and descriptive color-naming method for modifier porcelain. Consistent color naming is a step in improving communication over the use of modifying porcelains.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/68247/2/10.1177_00220345820610030801.pd
Adaptive weight estimator for quantum error correction
Quantum error correction of a surface code or repetition code requires the
pairwise matching of error events in a space-time graph of qubit measurements,
such that the total weight of the matching is minimized. The input weights
follow from a physical model of the error processes that affect the qubits.
This approach becomes problematic if the system has sources of error that
change over time. Here we show how the weights can be determined from the
measured data in the absence of an error model. The resulting adaptive decoder
performs well in a time-dependent environment, provided that the characteristic
time scale of the variations is greater than , with the duration of one error-correction cycle and
the typical error probability per qubit in one cycle.Comment: 5 pages, 4 figure
The optical variability of the narrow line Seyfert 1 galaxy IRAS 13224-3809
We report on a short optical monitoring programme of the narrow-line Seyfert
1 Galaxy IRAS 13224-3809. Previous X-ray observations of this object have shown
persistent giant variability. The degree of variability at other wavelengths
may then be used to constrain the conditions and emission processes within the
nucleus. Optical variability is expected if the electron population responsible
for the soft X-ray emission is changing rapidly and Compton-upscattering
infrared photons in the nucleus, or if the mechanism responsible for X-ray
emission causes all the emission processes to vary together. We find that there
is no significant optical variability with a firm upper limit of 2 per cent and
conclude that the primary soft X-ray emission region produces little of the
observed optical emission. The X-ray and optical emission regions must be
physically distinct and any reprocessing of X-rays into the optical waveband
occurs some distance from the nucleus. The lack of optical variability
indicates that the energy density of infrared radiation in the nucleus is at
most equal to that of the ultraviolet radiation since little is upscattered
into the optical waveband. The extremely large X-ray variability of IRAS
13224-3809 may be explained by relativistic boosting of more modest variations.
Although such boosting enhances X-ray variability over optical variability,
this only partially explains the lack of optical variability.Comment: 5 pages with 8 postscript figures. Accepted for publication in MNRA
- …