An alternative presentation of the Oxford purification protocol is obtained by using dynamical variables. I suggest to introduce the degree of separability as a purification parameter, where the purified state has a smaller degree of separability than the initial one. An improved version of the Oxford protocol is described, in which local unitary transformations optimize each step.
Cite
@article{arxiv.quant-ph/0109051,
title = {A more efficient variant of the Oxford protocol},
author = {Nasser Metwally},
journal= {arXiv preprint arXiv:quant-ph/0109051},
year = {2007}
}