Faithful qubit distribution assisted by one additional qubit against collective noise

Phys Rev Lett. 2005 Jul 22;95(4):040503. doi: 10.1103/PhysRevLett.95.040503. Epub 2005 Jul 22.


We propose a distribution scheme of polarization states of a single photon over a collective-noise channel. By adding one extra photon with a fixed polarization, we can protect the state against collective noise via a parity-check measurement and postselection. While the scheme succeeds only probabilistically, it is simpler and more flexible than the schemes utilizing decoherence-free subspace. An application to the Bennett-Brassard 1984 protocol through a collective-noise channel, which is robust to the Trojan horse attack, is also given.