11,481 research outputs found
Experimental Demonstration of Quantum State Multi-meter and One-qubit Fingerprinting in a Single Quantum Device
We experimentally demonstrate in NMR a quantum interferometric multi-meter
for extracting certain properties of unknown quantum states without resource to
quantum tomography. It can perform direct state determinations,
eigenvalue/eigenvector estimations, purity tests of a quantum system, as well
as the overlap of any two unknown quantum states. Using the same device, we
also demonstrate one-qubit quantum fingerprinting
Experimental demonstration of an efficient quantum phase-covariant cloning and its possible applications to simulating eavesdropping in quantum cryptography
We describe a nuclear magnetic resonance (NMR) experiment which implements an
efficient one-to-two qubit phase-covariant cloning machine(QPCCM). In the
experiment we have achieved remarkably high fidelities of cloning, 0.848 and
0.844 respectively for the original and the blank qubit. This experimental
value is close to the optimal theoretical value of 0.854. We have also
demonstrated how to use our phase-covariant cloning machine for quantum
simulations of bit by bit eavesdropping in the four-state quantum key
distribution protocol.Comment: 4 pages, 5 figure
The d* dibaryon in the extended quark-delocalization, color-screening model
The quark-delocalization, color-screening model, extended by inclusion of a
one-pion-exchange (OPE) tail, is applied to the study of the deuteron and the
d* dibaryon. The results show that the properties of the deuteron (an extended
object) are well reproduced, greatly improving the agreement with experimental
data as compared to our previous study (without OPE). At the same time, the
mass and decay width of the d* (a compact object) are, as expected, not altered
significantly.Comment: 9 pages, no figures, LaTeX, subm. to Phys. Rev.
Correspondence Between DGP Brane Cosmology and 5D Ricci-flat Cosmology
We discuss the correspondence between the DGP brane cosmology and 5D
Ricci-flat cosmology by letting their metrics equal each other. By this
correspondence, a specific geometrical property of the arbitrary integral
constant I in DGP metric is given and it is related to the curvature of 5D
bulk. At the same time, the relation of arbitrary functions and in
a class of Ricci-flat solutions is obtained from DGP brane metric.Comment: 8 pages, 1 figure, accepted by MPLA, added referenc
Power-law cosmological solution derived from DGP brane with a brane tachyon field
By studying a tachyon field on the DGP brane model, in order to embed the 4D
standard Friedmann equation with a brane tachyon field in 5D bulk, the metric
of the 5D spacetime is presented. Then, adopting the inverse square potential
of tachyon field, we obtain an expanding universe with power-law on the brane
and an exact 5D solution.Comment: 8 pages, 1 figure, accepted by IJMP
Experimental Quantum Cloning with Prior Partial Information
When prior partial information about a state to be cloned is available, it
can be cloned with a fidelity higher than that of universal quantum cloning. We
experimentally verify this intriguing relationship between the cloning fidelity
and the prior information by reporting the first experimental optimal quantum
state-dependent cloning, using nuclear magnetic resonance techniques. Our
experiments may further have important implications into many quantum
information processing protocols.Comment: 4 pages, 2 figure
Dark Energy in Global Brane Universe
We discuss the exact solutions of brane universes and the results indicate
the Friedmann equations on the branes are modified with a new density term.
Then, we assume the new term as the density of dark energy. Using Wetterich's
parametrization equation of state (EOS) of dark energy, we obtain the new term
varies with the red-shift z. Finally, the evolutions of the mass density
parameter , dark energy density parameter and deceleration
parameter q_2 are studied.Comment: 8 pages,4 figure
The d' dibaryon in the quark-delocalization, color-screening model
We study the questions of the existence and mass of the proposed dibaryon in the quark-delocalization, color-screening model
(QDCSM). The transformation between physical and symmetry bases has been
extended to the cases beyond the SU(2) orbital symmetry. Using parameters fixed
by baryon properties and scattering, we find a mild attraction in the
channel, but it is not strong enough to form a deeply bound state
as proposed for the state. Nor does the (isospin) I=2 N
configuration have a deeply bound state. These results show that if a narrow
dibaryon state does exist, it must have a more complicated structure.Comment: 12 pp. latex, no figs., 2 tables, additional refs., Report-no was
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