Purifications Without Entanglement, State Reconstructions and Entropy
Abstract
In this paper we have analysed in detail two different purification protocols. The first one, proposed by Sudarshan, is based on the preservation of probabilities.We have constructed a second protocol here based on optimisation of fidelities. We have considered both complete and partial measurements and have established bounds and inequalities for various fidelities. For every type of measurement, we have analysed post-measurement states based on the Maximum entropy principle as well as what we have proposed as unbiased states. We show that our purification protocol always leads to better state reconstruction. These schemes can be thought of as operations in the sense of Kraus and we have explicitly constructed the Kraus operators for these. We have also shown that the entropy either increases or remains the same depending on the choice of the purification basis.
Cite
@article{arxiv.quant-ph/0407156,
title = {Purifications Without Entanglement, State Reconstructions and Entropy},
author = {Chirag Dhara and N. D. Hari Dass},
journal= {arXiv preprint arXiv:quant-ph/0407156},
year = {2007}
}
Comments
6 pages in REVTEX4. This is a considerably extended and revised version of the earlier quant-ph/0407156. The analysis of maximum entropy states is a new feature. Many new results have been added. Earlier derivations have been simplified and made more transparent