131,621 research outputs found
A magnetically driven origin for the low luminosity GRB 170817A associated with GW170817
The gamma-ray burst GRB 170817A associated with GW170817 is subluminous and
subenergetic compared with other typical short GRBs. It may be due to a
relativistic jet viewed off-axis, or a structured jet, or cocoon emission.
Giant flares from magnetars may possibly be ruled out. However, the luminosity
and energetics of GRB 170817A is coincident with that of magnetar giant flares.
After the coalescence of the binary neutron star, a hypermassive neutron star
may be formed. The hypermassive neutron star may have magnetar-strength
magnetic field. During the collapse of the hypermassive neutron star, the
magnetic field energy will also be released. This giant-flare-like event may
explain the the luminosity and energetics of GRB 170817A. Bursts with similar
luminosity and energetics are expected in future neutron star-neutron star or
neutron star-black hole mergers.Comment: 6 pages, 1 figure, accepted in Research in Astronomy and Astrophysic
Effect of weak measurement on entanglement distribution over noisy channels
Being able to implement effective entanglement distribution in noisy
environments is a key step towards practical quantum communication, and
long-term efforts have been made on the development of it. Recently, it has
been found that the null-result weak measurement (NRWM) can be used to enhance
probabilistically the entanglement of a single copy of amplitude-damped
entangled state. This paper investigates remote distributions of bipartite and
multipartite entangled states in the amplitudedamping environment by combining
NRWMs and entanglement distillation protocols (EDPs). We show that the NRWM has
no positive effect on the distribution of bipartite maximally entangled states
and multipartite Greenberger-Horne-Zeilinger states, although it is able to
increase the amount of entanglement of each source state (noisy entangled
state) of EDPs with a certain probability. However, we find that the NRWM would
contribute to remote distributions of multipartite W states. We demonstrate
that the NRWM can not only reduce the fidelity thresholds for distillability of
decohered W states, but also raise the distillation efficiencies of W states.
Our results suggest a new idea for quantifying the ability of a local filtering
operation in protecting entanglement from decoherence.Comment: 15 pages, 9 figures. Minor revision has been mad
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