It is commonly assumed that Shor's quantum algorithm for the efficient factorization of a large number N requires a pure initial state. Here we demonstrate that a single pure qubit together with a collection of log2N qubits in an arbitrary mixed state is sufficient to implement Shor's factorization algorithm efficiently.
Cite
@article{arxiv.quant-ph/0001066,
title = {Efficient factorization with a single pure qubit and $log N$ mixed qubits},
author = {S. Parker and M. B. Plenio},
journal= {arXiv preprint arXiv:quant-ph/0001066},
year = {2009}
}
Comments
5 pages including 2 figures. Final version submitted to PRL. Now includes additional comments on entanglement and mixedness as algorithm proceeds. Added references to work by Mosca