598 research outputs found
Scheme for preparation of W state via cavity QED
In this paper, we presented a physical scheme to generate the multi-cavity
maximally entangled W state via cavity QED. All the operations needed in this
scheme are to modulate the interaction time only once.Comment: 8 pages, 1 figur
Equally-distant partially-entangled alphabet states for quantum channels
Each Bell state has the property that by performing just local operations on
one qubit, the complete Bell basis can be generated. That is, states generated
by local operations are totally distinguishable. This remarkable property is
due to maximal quantum entanglement between the two particles. We present a set
of local unitary transformations that generate out of partially entangled
two-qubit state a set of four maximally distinguishable states that are
mutually equally distant. We discuss quantum dense coding based on these
alphabet states.Comment: 7 revtex pages, 2 eps figures, to appear in Phys. Rev. A 62, 1
November (2000
Experimentally realizable quantum comparison of coherent states and its applications
When comparing quantum states to each other, it is possible to obtain an
unambiguous answer, indicating that the states are definitely different,
already after a single measurement. In this paper we investigate comparison of
coherent states, which is the simplest example of quantum state comparison for
continuous variables. The method we present has a high success probability, and
is experimentally feasible to realize as the only required components are beam
splitters and photon detectors. An easily realizable method for quantum state
comparison could be important for real applications. As examples of such
applications we present a "lock and key" scheme and a simple scheme for quantum
public key distribution.Comment: 14 pages, 5 figures, version one submitted to PRA. Version two is the
final accepted versio
Thrombolyse der Arteria cerebri media
Zusammenfassung: In den ersten 3h nach Eintritt eines akuten ischämischen Hirninfarkts ist die intravenöse Thrombolyse (IVT) die evidenzbasierte Therapie (IVT 3-4,5h: "off-label use" mit Einverständnis des Patienten). Die intraarterielle Thrombolyse (IAT) führt in der A.cerebri media (ACM) allerdings häufiger zur Rekanalisation als die IVT. Daher ist die IAT in dafür ausgerüsteten Kliniken ergänzend oder alternativ zur IVT bis zu 6h nach Symptombeginn zu erwäge
Experimental Realization of Teleporting an Unknown Pure Quantum State via Dual Classical and Einstein-Podolski-Rosen Channels
We report on a quantum optical experimental implementation of teleportation
of unknown pure quantum states. This realizes all the nonlocal aspects of the
original scheme proposed by Bennett et al. and is equivalent to it up to a
local operation. We exhibit results for the teleportation of a linearly
polarized state and of an elliptically polarized state. We show that the
experimental results cannot be explained in terms of a classical channel alone.Comment: 11 pages LaTeX, 3 figures, 1 page figures captions. The figures and
figures captions are not encapsulated; please print them separatel
Generalised Hong-Ou-Mandel Experiments with Bosons and Fermions
The Hong-Ou-Mandel (HOM) dip plays an important role in recent linear optics
experiments. It is crucial for quantum computing with photons and can be used
to characterise the quality of single photon sources and linear optics setups.
In this paper, we consider generalised HOM experiments with bosons or
fermions passing simultaneously through a symmetric Bell multiport beam
splitter. It is shown that for even numbers of bosons, the HOM dip occurs
naturally in the coincidence detection in the output ports. In contrast,
fermions always leave the setup separately exhibiting perfect coincidence
detection. Our results can be used to verify or employ the quantum statistics
of particles experimentally.Comment: 11 pages, 2 figures, more references adde
Tolerance of intravenous methylprednisolone for relapse treatment in demyelinating CNS disease
In Switzerland, the first course of intravenous steroids for treatment of episodes of demyelinating CNS disease is usually administered in an inpatient setting. We prospectively evaluated short term tolerance of treatment with special emphasis on sleep quality
Novel Cascaded Ultra Bright Pulsed Source of Polarization Entangled Photons
A new ultra bright pulsed source of polarization entangled photons has been
realized using type-II phase matching in spontaneous parametric down conversion
process in two cascaded crystals. The optical axes of the crystals are aligned
in such a way that the extraordinarily (ordinarily) polarized cone from one
crystal overlaps with the ordinarily (extraordinarily) polarized cone from the
second crystal. This spatial overlapping removes the association between the
polarization and the output angle of the photons that exist in a single type-II
down conversion process. Hence, entanglement of photons originating from any
point on the output cones is possible if a suitable optical delay line is used.
This delay line is particularly simple and easy to implement.Comment: 8 pages 8 figure
Vascular risk factors in the Swiss population
Background and Purpose : Identification of the population at risk of stroke remains the best approach to assess the burden of cardiovascular morbidity and mortality. Methods : The prevalence of hypertension (HT), hypercholesterolemia (HCh), diabetes mellitus (DM), overweight (OW), obesity (OB), tobacco use (SM), and their combinations was examined in 4458 Swiss persons (1741 men and 2717 women, mean age 57.8 ± 15 years), who volunteered for the present survey. Results : OW was the most prevalent risk factor (50 %), followed by HT (47%), HCh (33%), SM (13 %) and DM (1.6 %). The proportion of persons without risk factors (RF) was 19.9%, with 1 RF 41.5%, 2 RF 33.8%, 3 RF 4%, and 4 RF 0.9%. OW was more prevalent in men than in women (53% vs. 41%, P=0.02). More men than women aged 41-50 years and 51-60 years had HT (49 % vs. 36%, P=0.01, and 52 % vs. 42%, P=0.02). The prevalence of HCh and DM did not show any sex-related differences. HT, OW and HCh were not only the most common single risk factors, but were also most likely to aggregate with each other. Conclusions : The majority of Swiss people have one or two vascular risk factors. OW and HT are by far most common and are likely to aggregate with each other. A small modification of these two factors would reduce the incidence of stroke and myocardial infarction significantl
Trunk sway in mildly disabled multiple sclerosis patients with and without balance impairment
Multiple sclerosis (MS) causes a broad range of neurological symptoms. Most common is poor balance control. However, knowledge of deficient balance control in mildly affected MS patients who are complaining of balance impairment but have normal clinical balance tests (CBT) is limited. This knowledge might provide insights into the normal and pathophysiological mechanisms underlying stance and gait. We analysed differences in trunk sway between mildly disabled MS patients with and without subjective balance impairment (SBI), all with normal CBT. The sway was measured for a battery of stance and gait balance tests (static and dynamic posturography) and compared to that of age- and sex-matched healthy subjects. Eight of 21 patients (38%) with an Expanded Disability Status Scale of 1.0-3.0 complained of SBI during daily activities. For standing on both legs with eyes closed on a normal and on a foam surface, patients in the no SBI group showed significant differences in the range of trunk roll (lateral) sway angle and velocity, compared to normal persons. Patients in the SBI group had significantly greater lateral sway than the no SBI group, and sway was also greater than normal in the pitch (anterior-posterior) direction. Sway for one-legged stance on foam was also greater in the SBI group compared to the no SBI and normal groups. We found a specific laterally directed impairment of balance in all patients, consistent with a deficit in proprioceptive processing, which was greater in the SBI group than in the no SBI group. This finding most likely explains the subjective symptoms of imbalance in patients with MS with normal CBT
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