2,535 research outputs found
Quantum key distribution with realistic states: photon-number statistics in the photon-number splitting attack
Quantum key distribution can be performed with practical signal sources such
as weak coherent pulses. One example of such a scheme is the Bennett-Brassard
protocol that can be implemented via polarization of the signals, or equivalent
signals. It turns out that the most powerful tool at the disposition of an
eavesdropper is the photon-number splitting attack. We show that this attack
can be extended in the relevant parameter regime such as to preserve the
Poissonian photon number distribution of the combination of the signal source
and the lossy channel.Comment: 4 page
Unambiguous state discrimination in quantum cryptography with weak coherent states
The use of linearly independent signal states in realistic implementations of
quantum key distribution (QKD) enables an eavesdropper to perform unambiguous
state discrimination. We explore quantitatively the limits for secure QKD
imposed by this fact taking into account that the receiver can monitor to some
extend the photon number statistics of the signals even with todays standard
detection schemes. We compare our attack to the beamsplitting attack and show
that security against beamsplitting attack does not necessarily imply security
against the attack considered here.Comment: 10 pages, 6 figures, updated version with added discussion of
beamsplitting attac
Decoherence, Autler-Townes effect, and dark states in two-tone driving of a three-level superconducting system
We present a detailed theoretical analysis of a multi-level quantum system
coupled to two radiation fields and subject to decoherence. We concentrate on
an effect known from quantum optics as the Autler-Townes splitting, which has
been recently demonstrated experimentally [M. A. Sillanpaa et al., Phys. Rev.
Lett. 103, 193601 (2009)] in a superconducting phase qubit. In the three-level
approximation, we derive analytical solutions and describe how they can be used
to extract the decoherence rates and to account for the measurement data.
Better agreement with the experiment can be obtained by extending this model to
five levels. Finally, we investigate the stationary states created in the
experiment and show that their structure is close to that of dark states.Comment: 16 pages, 8 figure
Serum soluble T-H cell activity markers and high-sensitivity C-reactive protein in multiple-trigger wheezers
Peer reviewe
Stamp transferred suspended graphene mechanical resonators for radio-frequency electrical readout
We present a simple micromanipulation technique to transfer suspended
graphene flakes onto any substrate and to assemble them with small localized
gates into mechanical resonators. The mechanical motion of the graphene is
detected using an electrical, radio-frequency (RF) reflection readout scheme
where the time-varying graphene capacitor reflects a RF carrier at f=5-6 GHz
producing modulation sidebands at f +/- fm. A mechanical resonance frequency up
to fm=178 MHz is demonstrated. We find both hardening/softening Duffing effects
on different samples, and obtain a critical amplitude of ~40 pm for the onset
of nonlinearity in graphene mechanical resonators. Measurements of the quality
factor of the mechanical resonance as a function of DC bias voltage Vdc
indicate that dissipation due to motion-induced displacement currents in
graphene electrode is important at high frequencies and large Vdc
Mass uptake during oxidation of metallic alloys: literature data collection, analysis, and FAIR sharing
The area-normalized change of mass (m/A) with time during the
oxidation of metallic alloys is commonly used to assess oxidation resistance.
Analyses of such data can also aid in evaluating underlying oxidation
mechanisms. We performed an exhaustive literature search and digitized
normalized mass change vs. time data for 407 alloys. To maximize the impact of
these and future mass uptake data, we developed and published an open, online,
computational workflow that fits the data to various models of oxidation
kinetics, uses Bayesian statistics for model selection, and makes the raw data
and model parameters available via a queryable database. The tool, Refractory
Oxidation Database (https://nanohub.org/tools/refoxdb/), uses nanoHUB's Sim2Ls
to make the workflow and data (including metadata) findable, accessible,
interoperable, and reusable (FAIR). We find that the models selected by the
original authors do not match the most likely one according to the Bayesian
information criterion (BIC) in 71% of the cases. Further, in 56% of the cases,
the published model was not even in the top 3 models according to the BIC.
These numbers were obtained assuming an experimental noise of 2.5% of the mass
gain range, a smaller noise leads to more discrepancies. The RefOxDB tool is
open access and researchers can add their own raw data (those to be included in
future publications, as well as negative results) for analysis and to share
their work with the community. Such consistent and systematic analysis of open,
community generated data can significantly accelerate the development of
machine-learning models for oxidation behavior and assist in the understanding
and improvement of oxidation resistance
Lasmiditan for the acute treatment of migraine: Subgroup analyses by prior response to triptans.
BACKGROUND: Lasmiditan demonstrated superiority to placebo in the acute treatment of migraine in adults with moderate/severe migraine disability in two similarly designed Phase 3 trials, SAMURAI and SPARTAN. Post-hoc integrated analyses evaluated the efficacy of lasmiditan in patients who reported a good or insufficient response to triptans and in those who were triptan naïve.
METHODS: Subgroups of patients reporting an overall response of good or poor/none to the most recent use of a triptan at baseline (defined as good or insufficient responders, respectively) and a triptan-naïve subpopulation were derived from combined study participants randomized to receive lasmiditan 50 mg (SPARTAN only), 100 mg or 200 mg, or placebo, as the first dose. Outcomes including headache pain-freedom, most bothersome symptom-freedom, and headache pain relief 2 hours post-first dose of lasmiditan were compared with placebo. Treatment-by-subgroup analyses additionally investigated whether therapeutic benefit varied according to prior triptan response (good or insufficient).
RESULTS: Regardless of triptan response, lasmiditan showed higher efficacy than placebo (most comparisons were statistically significant). Treatment-by-subgroup analyses found that the benefit over placebo of lasmiditan did not vary significantly between patients with a good response and those with an insufficient response to triptans. Lasmiditan also showed higher efficacy than placebo in triptan-naïve patients.
CONCLUSIONS: Lasmiditan demonstrated comparable efficacy in patients who reported a good or insufficient response to prior triptan use. Lasmiditan also showed efficacy in those who were triptan naïve. Lasmiditan may be a useful therapeutic option for patients with migraine.
TRIAL REGISTRATION: SAMURAI (NCT02439320); SPARTAN (NCT02605174)
Toll-like receptor signaling adapter proteins govern spread of neuropathic pain and recovery following nerve injury in male mice.
BackgroundSpinal Toll-like receptors (TLRs) and signaling intermediaries have been implicated in persistent pain states. We examined the roles of two major TLR signaling pathways and selected TLRs in a mononeuropathic allodynia.MethodsL5 spinal nerve ligation (SNL) was performed in wild type (WT, C57BL/6) male and female mice and in male Tlr2-/-Tlr3-/-, Tlr4-/-, Tlr5-/-, Myd88-/-, Triflps2, Myd88/Triflps2, Tnf-/-, and Ifnar1-/- mice. We also examined L5 ligation in Tlr4-/- female mice. We examined tactile allodynia using von Frey hairs. Iba-1 (microglia) and GFAP (astrocytes) were assessed in spinal cords by immunostaining. Tactile thresholds were analyzed by 1- and 2-way ANOVA and the Bonferroni post hoc test was used.ResultsIn WT male and female mice, SNL lesions resulted in a persistent and robust ipsilateral, tactile allodynia. In males with TLR2, 3, 4, or 5 deficiencies, tactile allodynia was significantly, but incompletely, reversed (approximately 50%) as compared to WT. This effect was not seen in female Tlr4-/- mice. Increases in ipsilateral lumbar Iba-1 and GFAP were seen in mutant and WT mice. Mice deficient in MyD88, or MyD88 and TRIF, showed an approximately 50% reduction in withdrawal thresholds and reduced ipsilateral Iba-1. In contrast, TRIF and interferon receptor null mice developed a profound ipsilateral and contralateral tactile allodynia. In lumbar sections of the spinal cords, we observed a greater increase in Iba-1 immunoreactivity in the TRIF-signaling deficient mice as compared to WT, but no significant increase in GFAP. Removing MyD88 abrogated the contralateral allodynia in the TRIF signaling-deficient mice. Conversely, IFNβ, released downstream to TRIF signaling, administered intrathecally, temporarily reversed the tactile allodynia.ConclusionsThese observations suggest a critical role for the MyD88 pathway in initiating neuropathic pain, but a distinct role for the TRIF pathway and interferon in regulating neuropathic pain phenotypes in male mice
Characterization of altered mica from Sokli, northern Finland
Vermiculite is a mineral with many potential uses in various industrial areas, such as in insulation, horticulture, and environmental applications. The regolith of the Sokli carbonatite intrusion in northern Finland consists of weathered micas which reportedly contain vermiculite. The aim of the present study was to characterize the weathered mica in order to determine if the weathered regolith contains vermiculite. If so, the value of the apatite-rich Sokli intrusion may increase, because the vermiculite could be classified as an ore in Sokli. For the characterization, mica fractions were investigated using electron probe microanalysis (EPMA), X-ray diffraction (XRD), and thermogravimetric analysis (TGA). The EPMA results show that the potassium (K2O) content of the mica investigated varies between 6.20 and 0.31 wt.%. The XRD results provided evidence thatthe interlayer distances in the mica vary between 10.1 and 14.7 Å. The TGA shows that the dehydration of the samples varies between 6 and 12 wt.% for temperatures up to 170°C. Dehydroxylation takes place in three steps, as is characteristic for vermiculite. The results from this study revealed that mica in the weathered parts of the Sokli carbonatite is mostly vermiculite, and that the vermiculite was formed by the weathering of phlogopite. These results can be used to determine whether vermiculite is a possible future commodity at the Sokli carbonatite complex.</p
Coherent quantum state storage and transfer between two phase qubits via a resonant cavity
A network of quantum-mechanical systems showing long lived phase coherence of
its quantum states could be used for processing quantum information. As with
classical information processing, a quantum processor requires information bits
(qubits) that can be independently addressed and read out, long-term memory
elements to store arbitrary quantum states, and the ability to transfer quantum
information through a coherent communication bus accessible to a large number
of qubits. Superconducting qubits made with scalable microfabrication
techniques are a promising candidate for the realization of a large scale
quantum information processor. Although these systems have successfully passed
tests of coherent coupling for up to four qubits, communication of individual
quantum states between qubits via a quantum bus has not yet been demonstrated.
Here, we perform an experiment demonstrating the ability to coherently transfer
quantum states between two superconducting Josephson phase qubits through a
rudimentary quantum bus formed by a single, on chip, superconducting
transmission line resonant cavity of length 7 mm. After preparing an initial
quantum state with the first qubit, this quantum information is transferred and
stored as a nonclassical photon state of the resonant cavity, then retrieved at
a later time by the second qubit connected to the opposite end of the cavity.
Beyond simple communication, these results suggest that a high quality factor
superconducting cavity could also function as a long term memory element. The
basic architecture presented here is scalable, offering the possibility for the
coherent communication between a large number of superconducting qubits.Comment: 17 pages, 4 figures (to appear in Nature
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