23,562 research outputs found
Cocycle deformations and Galois objects of semisimple Hopf algebras of dimension
In this article, we determine cocycle deformations and Galois objects of
non-commutative and non-cocommutative semisimple Hopf algebras of dimension
. We show that these Hopf algebras are pairwise twist inequivalent mainly
by calculating their higher Frobenius-Schur indicators, and that except three
Hopf algebras which are cocycle deformations of dual group algebras, none of
them admit non-trivial cocycle deformations.Comment: 22 page
Quasi Distribution Amplitude of Heavy Quarkonia
The recently-proposed quasi distributions point out a promising direction for
lattice QCD to investigate the light-cone correlators, such as parton
distribution functions (PDF) and distribution amplitudes (DA), directly in the
-space. Owing to its excessive simplicity, the heavy quarkonium can serve as
an ideal theoretical laboratory to ascertain certain features of quasi-DA. In
the framework of non-relativistic QCD (NRQCD) factorization, we compute the
order- correction to both light-cone distribution amplitudes (LCDA)
and quasi-DA associated with the lowest-lying quarkonia, with the transverse
momentum UV cutoff interpreted as the renormalization scale. We confirm
analytically that the quasi-DA of a quarkonium does reduce to the respective
LCDA in the infinite-momentum limit. We also observe that, provided that the
momentum of a charmonium reaches about 2-3 times its mass, the quasi-DAs
already converge to the LCDAs to a decent level. These results might provide
some useful guidance for the future lattice study of the quasi distributions.Comment: 32 pages, 5 Figures, 1 tabl
Robust quantum repeater with atomic ensembles and single-photon sources
We present a quantum repeater protocol using atomic ensembles, linear optics
and single-photon sources. Two local 'polarization' entangled states of atomic
ensembles and are generated by absorbing a single photon emitted by an
on-demand single-photon sources, based on which high-fidelity local
entanglement between four ensembles can be established efficiently through
Bell-state measurement. Entanglement in basic links and entanglement connection
between links are carried out by the use of two-photon interference. In
addition to being robust against phase fluctuations in the quantum channels,
this scheme may speed up quantum communication with higher fidelity by about 2
orders of magnitude for 1280 km compared with the partial read (PR) protocol
(Sangouard {\it et al.}, Phys. Rev. A {\bf77}, 062301 (2008)) which may
generate entanglement most quickly among the previous schemes with the same
ingredients.Comment: 5 pages 4 figure
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