We show that a set of optical memories can act as a configurable linear optical network operating on frequency-multiplexed optical states. Our protocol is applicable to any quantum memories that employ off-resonant Raman transitions to store optical information in atomic spins. In addition to the configurability, the protocol also offers favourable scaling with an increasing number of modes where N memories can be configured to implement an arbitrary N-mode unitary operations during storage and readout. We demonstrate the versatility of this protocol by showing an example where cascaded memories are used to implement a conditional CZ gate.
@article{arxiv.1311.1889,
title = {Configurable unitary transformations and linear logic gates using quantum memories},
author = {G. T. Campbell and O. Pinel and M. Hosseini and T. C. Ralph and B. C. Buchler and P. K. Lam},
journal= {arXiv preprint arXiv:1311.1889},
year = {2014}
}