3,574 research outputs found
Model-Independent Constraints on Lorentz Invariance Violation via the Cosmographic Approach
Since Lorentz invariance plays an important role in modern physics, it is of
interest to test the possible Lorentz invariance violation (LIV). The time-lag
(the arrival time delay between light curves in different energy bands) of
Gamma-ray bursts (GRBs) has been extensively used to this end. However, to our
best knowledge, one or more particular cosmological models were assumed {\it a
priori} in (almost) all of the relevant works in the literature. So, this makes
the results on LIV in those works model-dependent and hence not so robust in
fact. In the present work, we try to avoid this problem by using a
model-independent approach. We calculate the time delay induced by LIV with the
cosmic expansion history given in terms of cosmography, without assuming any
particular cosmological model. Then, we constrain the possible LIV with the
observational data, and find weak hints for LIV.Comment: 15 pages, 4 figures, 3 tables, revtex4; v2: discussions added, Phys.
Lett. B in pres
Multi-particle and High-dimension Controlled Order Rearrangement Encryption Protocols
Based on the controlled order rearrange encryption (CORE) for quantum key
distribution using EPR pairs[Fu.G.Deng and G.L.Long Phys.Rev.A68 (2003)
042315], we propose the generalized controlled order rearrangement encryption
(GCORE) protocols of qubits and qutrits, concretely display them in the
cases using 3-qubit, 2-qutrit maximally entangled basis states. We further
indicate that our protocols will become safer with the increase of number of
particles and dimensions. Moreover, we carry out the security analysis using
quantum covariant cloning machine for the protocol using qutrits. Although the
applications of the generalized scheme need to be further studied, the GCORE
has many distinct features such as great capacity and high efficiency
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