9,563 research outputs found
Enhanced quantum teleportation in the background of Schwarzschild spacetime by weak measurements
It is commonly believed that the fidelity of quantum teleportation in the
gravitational field would be degraded due to the heat up by the Hawking
radiation. In this paper, we point out that the Hawking effect could be
eliminated by the combined action of pre- and post-weak measurements, and thus
the teleportation fidelity is almost completely protected. It is intriguing to
notice that the enhancement of fidelity could not be attributed to the
improvement of entanglement, but rather to the probabilistic nature of weak
measurements. Our work extends the ability of weak measurements as a quantum
technique to battle against gravitational decoherence in relativistic quantum
information.Comment: 9 pages, 5 figures, comments are welcom
Enhancing teleportation of quantum Fisher information by partial measurements
The purport of quantum teleportation is to completely transfer information
from one party to another distant partner. However, from the perspective of
parameter estimation, it is the information carried by a particular parameter,
not the information of total quantum state that needs to be teleported. Due to
the inevitable noise in environment, we propose two schemes to enhance quantum
Fisher information (QFI) teleportation under amplitude damping noise with the
technique of partial measurements. We find that post partial measurement can
greatly enhance the teleported QFI, while the combination of prior partial
measurement and post partial measurement reversal could completely eliminate
the effect of decoherence. We show that, somewhat consequentially, enhancing
QFI teleportation is more economic than that of improving fidelity
teleportation. Our work extends the ability of partial measurements as a
quantum technique to battle decoherence in quantum information processing.Comment: Revised version, minor changes, accepted by Phys. Rev.
Protecting entanglement from correlated amplitude damping channel using weak measurement and quantum measurement reversal
Based on the quantum technique of weak measurement, we propose a scheme to
protect the entanglement from correlated amplitude damping decoherence. In
contrast to the results of memoryless amplitude damping channel, we show that
the memory effects play a significant role in the suppression of entanglement
sudden death and protection of entanglement under severe decoherence. Moreover,
we find that the initial entanglement could be drastically amplified by the
combination of weak measurement and quantum measurement reversal even under the
correlated amplitude damping channel. The underlying mechanism can be
attributed to the probabilistic nature of weak measurements.Comment: 11 pages, 5 figures, accepted by Quantum Information Processin
Leading Effect of CP Violation with Four Generations
In the Standard Model with a fourth generation of quarks, we study the
relation between the Jarlskog invariants and the triangle areas in the 4-by-4
CKM matrix. To identify the leading effects that may probe the CP violation in
processes involving quarks, we invoke small mass and small angle expansions,
and show that these leading effects are enhanced considerably compared to the
three generation case by the large masses of fourth generation quarks. We
discuss the leading effect in several cases, in particular the possibility of
large CP violation in processes, which echoes the heightened recent
interest because of experimental hints.Comment: 12 pages, no figur
Evolving Starburst Modeling of FIR/sub-mm/mm Line Emission. III. Application to Nearby Luminous Infrared Galaxies
In a previous work, we showed that the observed FIR/sub-mm/mm line spectra of
a starburst galaxy (M 82) can be successfully modeled in terms of the
evolutionary scheme of an ensemble of giant molecular clouds (GMCs) and shells,
and such studies can usefully constrain the age(s) or star formation history of
a starburst galaxy. In this paper we present a preliminary study of using the
template of an ensemble of evolving GMCs/shells we developed for M 82. we apply
the model to represent various stages of starburst evolution in a well known
sample of nearby luminous infrared galaxies (LIRGs). In this way, we attempt to
interpret the relationship between the degree of molecular excitation and ratio
of far-infrared (FIR) to CO (or simply CO) luminosity to possibly
reflect different stages of the evolution of star-forming activity within their
nuclear regions.Comment: Accepted for publication in the ApJ, 16 pages, 4 figures
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