We outline a proposal for a method of preparing an encoded two-state system (logical qubit) that is immune to collective noise acting on the Hilbert space of the states supporting it. The logical qubit is comprised of three photonic three-state systems (qutrits) and is generated by the process of spontaneous parametric down conversion. The states are constructed using linear optical elements along with three down-conversion sources, and are deemed successful by the simultaneous detection of six events. We also show how to select a maximally entangled state of two qutrits by similar methods. For this maximally entangled state we describe conditions for the state to be decoherence-free which do not correspond to collective errors.
@article{arxiv.0709.0021,
title = {Methods for Producing Decoherence-Free States and Noiseless Subsystems Using Photonic Qutrits},
author = {C. Allen Bishop and Mark S. Byrd},
journal= {arXiv preprint arXiv:0709.0021},
year = {2009}
}
Comments
12 pages, 9 (color) figures, misc minor changes from referee suggestions and an added reference