We present a number of rapid-purification feedback protocols for optical homodyne detection of a single optical qubit. We derive first a protocol that speeds up the rate of increase of the average purity of the system, and find that like the equivalent protocol for a non-disspative measurement, this generates a deterministic evolution for the purity in the limit of strong feedback. We also consider two analogues of the Wiseman-Ralph rapid-purification protocol in this setting, and show that like that protocol they speed up the average time taken to reach a fixed level of purity. We also examine how the performance of these algorithms changes with detection efficiency, being an important practical consideration.
Cite
@article{arxiv.0709.3867,
title = {Rapid-purification protocols for optical homodyning},
author = {Aravind Chiruvelli and Kurt Jacobs},
journal= {arXiv preprint arXiv:0709.3867},
year = {2009}
}