Thursday, December 15, 2011

Spectroscopy of a black hole and its horizon entropy

The idea of Isolated and Dynamical Horizon theory was first worked out by Heyward in 1994. He derived the complete definition of a marginally null surface that is trapped on a black hole horizon.

A few years later Ashtekar and his colleagues re-wrote the same theory in the language of Ashtekar- Sen variables. Before this development Rovelli has argued that a black hole entropy should be proportional with its horizon area. Lee Smolin linked loop quantum gravity to topological field theory and argued that a black hole should be described by a Chern Simon’s action.

Later on, Krasnov based on all the above mentioned ideas argued the derivation of a black hole entropy from the counting of puncture states. A ‘sequence’ of punctures on a horizon explains the wave function of the horizon. Being a sequence, the punctures are ordered and this make them distinguishable. However, there is no physical evidence why should one restricts the wave functions into a sequence and not a set of punctures in which there is no generic order, thus no distinguishability.

Given this in the quantum horizon theory, I noticed an internal degeneracy in the nature of area operator. Since the area eigenstates are insensitive to the completely tangential edges residing on the horizon, the edges describing a quantum surface carries a local distinguishability. The complete spectrum of area provides the Bekenstein-Hawking entropy, which using Olaf Dreyer’s conjecture it becomes consistent with the evaporation of minimal area cell with the corresponding area of the highly damping quanta.

This proposes a kinematical picture for defining a quantum horizon via spin foam models, however the dynamics of such a model has not yet initiated to be studied. . A new value was devoted to the Immirzi parameter. Considering the full spectrum of area and using the semi-classical conjecture that on a black hole the horizon area and the hole energy are proportional

I noticed a strong amplification in some selected frequencies radiated away from a black hole due to its horizon fluctuations. The full spectrum of a black hole radiation was extracted and the bright lines in the spectrum turn out to be unblended and narrow enough to become observable.

Tuesday, December 13, 2011

Josephson and Feynman in low temperature!

We recently calculated noise power spectrum due to the presence of magnetic impurities in a Josephson junction explicitly, using Feynman diagrams. The long paper includes all details of integrations and calculations.

The results were presented is written in a way that serves as a good source to understand step by step the details of analysis of decoherence in mesoscopic superconducting systems that includes the Kondo effect through the Coulomb interactions Feynman diagrams in low temperature.

It was recently published in PRB in 19 pages.