An Application of Lorentz Invariance Violation in Black Hole Thermodynamics

In this paper, we have applied the Lorentz-invariance-violation (LIV) class of dispersion relations (DR) with the dimensionless parameter n = 2 and the "sign of LIV" {\eta}_+ = 1, to phenomenologically study the effect of quantum gravity in the strong gravitational field. Specifically, we have studied the effect of the LIV-DR induced quantum gravity on the Schwarzschild black hole thermodynamics. The result shows that the effect of the LIV-DR induced quantum gravity speeds up the black hole evaporation, and its corresponding black hole entropy undergoes a leading logarithmic correction to the "reduced Bekenstein-Hawking entropy", and the ill defined situations (i.e. the singularity problem and the critical problem) are naturally bypassed when the LIV-DR effect is present. Also, to put our results in a proper perspective, we have compared with the earlier findings by another quantum gravity candidate, i.e. the generalized uncertainty principle (GUP). Finally, we conclude from the inert remnants at the final stage of the black hole evaporation that, the GUP as a candidate for describing quantum gravity can always do as well as the LIV-DR by adjusting the model-dependent parameters, but in the same model-dependent parameters the LIV-DR acts as a more suitable candidate.Comment: 18 pages, 7 figure

Continuous-variable controlled-Z gate using an atomic ensemble

The continuous-variable controlled-Z gate is a canonical two-mode gate for universal continuous-variable quantum computation. It is considered as one of the most fundamental continuous-variable quantum gates. Here we present a scheme for realizing continuous-variable controlled-Z gate between two optical beams using an atomic ensemble. The gate is performed by simply sending the two beams propagating in two orthogonal directions twice through a spin-squeezed atomic medium. Its fidelity can run up to one if the input atomic state is infinitely squeezed. Considering the noise effects due to atomic decoherence and light losses, we show that the observed fidelities of the scheme are still quite high within presently available techniques.Comment: 7 pages, 3 figures, to appear in Physical Review

Analysis on Safety of Removing the Closure Segment in a Prestressed Concrete Cable-stayed Bridge

AbstractAiming at failure of closure segment in a prestressed concrete cable-stayed bridge, a strengthening technology, namely replacing the closure segment, was firstly put forward. But removing the old closure segment was a process of release of internal force and had great risk. So the structural safety possibly induced by removing must be analyzed and confirmed. Based on FEM and summary of engineering experience, the construction stages for removing the old closure segment were simulated, and then some analysis relevant to safety, including thermal effect, dynamic characteristics and global stability of the whole bridge structure, were systematically presented. According to these analysis results, corresponding prevention and control measures were provided to ensure construction safety. Studies showed that, variation range of its structural state between before and after removing is not obvious, and its dynamic characteristics changed little after removing. In addition, structural instability could not be induced by removing, but for the sake of improving construction safety reliability, necessary safety prevention and control measures were indispensable. Analysis on safety of removing the old closure segment constituted the important part of the strengthening technology of replacing the closure segment, and became the theoretical basis of removing partial structural members for existing bridges