77,033 research outputs found
Ultrafast switching of photonic entanglement
To deploy and operate a quantum network which utilizes existing
telecommunications infrastructure, it is necessary to be able to route
entangled photons at high speeds, with minimal loss and signal-band noise,
and---most importantly---without disturbing the photons' quantum state. Here we
present a switch which fulfills these requirements and characterize its
performance at the single photon level; it exhibits a 200-ps switching window,
a 120:1 contrast ratio, 1.5 dB loss, and induces no measurable degradation in
the switched photons' entangled-state fidelity (< 0.002). Furthermore, because
this type of switch couples the temporal and spatial degrees of freedom, it
provides an important new tool with which to encode multiple-qubit states in a
single photon. As a proof-of-principle demonstration of this capability, we
demultiplex a single quantum channel from a dual-channel,
time-division-multiplexed entangled photon stream, effectively performing a
controlled-bit-flip on a two-qubit subspace of a five-qubit, two-photon state
The late-time development of the Richtmyer–Meshkov instability
Measurements have been made of the growth by the Richtmyer–Meshkov instability of nominally single-scale perturbations on an air/sulfur hexafluoride (SF6) interface in a large shock tube. An approximately sinusoidal shape is given to the interface by a wire mesh which supports a polymeric membrane separating the air from the SF6. A single shock wave incident on the interface induces motion by the baroclinic mechanism of vorticity generation. The visual thickness delta of the interface is measured from schlieren photographs obtained singly in each run and in high-speed motion pictures. Data are presented for delta at times considerably larger than previously reported, and they are tested for self-similarity including independence of initial conditions. Four different initial amplitude/wavelength combinations at one incident shock strength are used to determine the scaling of the data. It is found that the growth rate decreases rapidly with time, ddelta/dt[proportional]t–p (i.e., delta[proportional]t1–p), where 0.67<~p<~0.74 and that a small dependence on the initial wavelength lambda0 persists to large time. The larger value of the power law exponent agrees with the result of the late-time-decay similarity law of Huang and Leonard [Phys. Fluids 6, 3765–3775 (1994)]. The influence of the wire mesh and membrane on the mixing process is assessed
Electron-hole coexistence in disordered graphene probed by high-field magneto-transport
We report on magneto-transport measurement in disordered graphene under
pulsed magnetic field of up to 57T. For large electron or hole doping, the
system displays the expected anomalous Integer Quantum Hall Effect (IQHE)
specific to graphene up to filling factor . In the close vicinity of the
charge neutrality point, the system breaks up into co-existing puddles of holes
and electrons, leading to a vanishing Hall and finite longitudinal resistance
with no hint of divergence at very high magnetic field. Large resistance
fluctuations are observed near the Dirac point. They are interpreted as the the
natural consequence of the presence of electron and hole puddles. The magnetic
field at which the amplitude of the fluctuations are the largest is directly
linked to the mean size of the puddles
The structure of the central disk of NGC 1068: a clumpy disk model
NGC 1068 is one of the best studied Seyfert II galaxies, for which the
blackhole mass has been determined from the Doppler velocities of water maser.
We show that the standard -disk model of NGC 1068 gives disk mass
between the radii of 0.65 pc and 1.1 pc (the region from which water maser
emission is detected) to be about 7x10 M (for ), more
than four times the blackhole mass, and a Toomre Q-parameter for the disk is
0.001. This disk is therefore highly self-gravitating and is subject to
large-amplitude density fluctuations. We conclude that the standard
-viscosity description for the structure of the accretion disk is
invalid for NGC 1068.
In this paper we develop a new model for the accretion disk. The disk is
considered to be composed of gravitationally bound clumps; accretion in this
clumped disk model arises because of gravitational interaction of clumps with
each other and the dynamical frictional drag exerted on clumps from the stars
in the central region of the galaxy. The clumped disk model provides a
self-consistent description of the observations of NGC 1068. The computed
temperature and density are within the allowed parameter range for water maser
emission, and the rotational velocity in the disk falls off as .Comment: To appear in Ap
ANTIMICROBIAL AND ANTIOXIDANT ACTIVITY OF CYCAS CIRCINALIS.L AND IONIDIUM SUFFRUTICOSUM. GING
Herbs with antioxidants and antimicrobial activity play a vital role in prevention and cure of certain complex diseases. Cycas circinalis and Ionidium Suffruticosum are the herbs taken to study its antimicrobial and antioxidant activity. The ethanolic extract of the above 2 herbs were taken and the antimicrobial activity was studied by Kirby-Bauer disk diffusion method and the antioxidant activity was analyzed by percentage inhibition of DPPH activity. Around 8 species of microorganisms were taken for antimicrobial assay. The Cycas circinalis showed 0.7mm of zone of inhibition for Staphylococcus aureus in culture whereas Ionidium Suffruticosum showed 1mm and 0.4 mm of zone of inhibition for Escherichia colli and Salmonella typhi respectively. The rest of all species were non-reactive for both the herbal extracts. The IC50 values of I.suffruticosum at various concentrations were 95.6, 96.0 and 97.6 respectively whereas for C.circinalis, it was 78.7, 85.9 and 87.5 respectively. The IC50 value of I.suffruticosum shows that the herb has more antioxidant property when compared to that of C.circinalis and standard (ascorbic acid). The study shows that I.suffruticosum and C.circinalis both have mild antimicrobial activity acting only on 2 species of bacteria and the rest were dormant. I.suffruticosum and C.circinalis both were found to have antioxidant activity. This is a preliminary study done on the above 2 herbs which is a part of vast ongoing research work
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