268 research outputs found
Quantum Key Distribution using Multilevel Encoding: Security Analysis
We present security proofs for a protocol for Quantum Key Distribution (QKD)
based on encoding in finite high-dimensional Hilbert spaces. This protocol is
an extension of Bennett's and Brassard's basic protocol from two bases, two
state encoding to a multi bases, multi state encoding. We analyze the mutual
information between the legitimate parties and the eavesdropper, and the error
rate, as function of the dimension of the Hilbert space, while considering
optimal incoherent and coherent eavesdropping attacks. We obtain the upper
limit for the legitimate party error rate to ensure unconditional security when
the eavesdropper uses incoherent and coherent eavesdropping strategies. We have
also consider realistic noise caused by detector's noise.Comment: 8 pages, 3 figures, REVTe
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
Constructing Agency: The Role of Language
Is agency a straightforward and universal feature of human experience? Or is the construction of agency (including attention to and memory for people involved in events) guided by patterns in culture? In this paper we focus on one aspect of cultural experience: patterns in language. We examined English and Japanese speakers’ descriptions of intentional and accidental events. English and Japanese speakers described intentional events similarly, using mostly agentive language (e.g., “She broke the vase”). However, when it came to accidental events English speakers used more agentive language than did Japanese speakers. We then tested whether these different patterns found in language may also manifest in cross-cultural differences in attention and memory. Results from a non-linguistic memory task showed that English and Japanese speakers remembered the agents of intentional events equally well. However, English speakers remembered the agents of accidents better than did Japanese speakers, as predicted from patterns in language. Further, directly manipulating agency in language during another laboratory task changed people’s eye-witness memory, confirming a possible causal role for language. Patterns in one’s linguistic environment may promote and support how people instantiate agency in context
Geometric Quantum Computation
We describe in detail a general strategy for implementing a conditional
geometric phase between two spins. Combined with single-spin operations, this
simple operation is a universal gate for quantum computation, in that any
unitary transformation can be implemented with arbitrary precision using only
single-spin operations and conditional phase shifts. Thus quantum geometrical
phases can form the basis of any quantum computation. Moreover, as the induced
conditional phase depends only on the geometry of the paths executed by the
spins it is resilient to certain types of errors and offers the potential of a
naturally fault-tolerant way of performing quantum computation.Comment: 15 pages, LaTeX, uses cite, eepic, epsfig, graphicx and amsfonts.
Accepted by J. Mod. Op
Signal Detection Performance of Overlapped FFT Scheme with Additional Frames Consisting of Non-continuous Samples in Indoor Environment
Overlapped FFT has been proposed as a signal detection scheme in dynamic spectrum access to reduce the variance of the noise and improve the detection probability. However, the improvement of the detection probability in the conventional overlapped FFT is bounded with the upper limit of the overlap ratio. This paper proposes a new overlapped FFT scheme using additional frames. In the proposed scheme, in addition to the original FFT frames, new frames that consist of multiple subframes with non-continuous samples are constructed and included. It can realize the increase of the number of the FFT frames and the improvement of the detection probability compared with the conventional scheme. Numerical results through computer simulation show that the proposed scheme improves the detection probability by up to 0.07. On indoor channel models the proposed scheme also improves the detection probability. In addition, it is clarified that as the delay spread increases the detection probability reduces due to the correlation between the frames
Early effect of oral administration of omeprazole with mosapride as compared with those of omeprazole alone on the intragastric pH
<p>Abstract</p> <p>Background</p> <p>The ideal medication for acid-related diseases should have a rapid onset of action to promote hemostasis and cause efficient resolution of symptoms. The aim of our study was to comparatively investigate the inhibitory effect on gastric acid secretion of a single oral administration of omeprazole plus mosapride with that of omeprazole alone.</p> <p>Methods</p> <p>Ten Helicobacter pylori-negative male subjects participated in this randomized, two-way crossover study. Intragastric pH was monitored continuously for 6 hours after a single oral administration of omeprazole 20 mg or that of omeprazole 20 mg plus mosapride 5 mg (the omeprazole being administered one hour after the mosapride). Each administration was separated by a 7-days washout period.</p> <p>Results</p> <p>The average pH during the 6-hour period after administration of omeprazole 20 mg plus mosapride 5 mg was higher than that after administration of omeprazole 20 mg alone (median: 3.22 versus 4.21, respectively; <it>p </it>= 0.0247).</p> <p>Conclusions</p> <p>In H. pylori -negative healthy male subjects, an oral dose of omeprazole 20 mg plus mosapride 5 mg increased the intragastric pH more rapidly than omeprazole 20 mg alone.</p
Gastric Varices with Remarkable Collateral Veins in Valpronic Acid-Induced Chronic Pancreatitis
Valproic acid (VPA) is a commonly prescribed and approved treatment for epilepsy, including Angelman syndrome, throughout the world. However, the long-term administration of drugs like VPA is associated with the possible development of gastric varices and splenic obstruction as a result of chronic pancreatitis. Such cases can be difficult to treat using endoscopy or interventional radiology because of hemodynamic abnormalities; therefore, surgical treatment is often necessary
Gastric Inflammatory Fibroid Polyp Treated by Endoscopic Submucosal Dissection
The endoscopic examination of a 64-year-old male patient revealed a gastric submucosal tumor in the anterior wall of the gastric antrum. The lesion increased in diameter to 25 mm and was resected completely with endoscopic submucosal dissection (ESD). Histological examination of the submucosal tumor gave a diagnosis of an inflammatory fibroid polyp (IFP). It is suggested that ESD may be an effective and safe therapy for gastric submucosal tumors
General theory for decoy-state quantum key distribution with arbitrary number of intensities
We develop a general theory for quantum key distribution (QKD) in both the
forward error correction and the reverse error correction cases when the QKD
system is equipped with phase-randomized coherent light with arbitrary number
of decoy intensities. For this purpose, generalizing Wang's expansion, we
derive a convex expansion of the phase-randomized coherent state. We also
numerically check that the asymptotic key generation rates are almost saturated
when the number of decoy intensities is three.Comment: This manuscript has been revised extensivel
Solution to Satisfiability problem by a complete Grover search with trapped ions
The main idea in the original Grover search (Phys. Rev. Lett. 79, 325 (1997))
is to single out a target state containing the solution to a search problem by
amplifying the amplitude of the state, following the Oracle's job, i.e., a
black box giving us information about the target state. We design quantum
circuits to accomplish a complete Grover search involving both the Oracle's job
and the amplification of the target state, which are employed to solve
Satisfiability (SAT) problems. We explore how to carry out the quantum circuits
by currently available ion-trap quantum computing technology.Comment: 14 pages, 6 figure
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