We investigate a hybrid quantum circuit where ensembles of cold polar molecules serve as long-lived quantum memories and optical interfaces for solid state quantum processors. The quantum memory realized by collective spin states (ensemble qubit) is coupled to a high-Q stripline cavity via microwave Raman processes. We show that for convenient trap-surface distances of a few μm, strong coupling between the cavity and ensemble qubit can be achieved. We discuss basic quantum information protocols, including a swap from the cavity photon bus to the molecular quantum memory, and a deterministic two qubit gate. Finally, we investigate coherence properties of molecular ensemble quantum bits.
@article{arxiv.quant-ph/0604140,
title = {Hybrid Quantum Processors: molecular ensembles as quantum memory for solid state circuits},
author = {P. Rabl and D. DeMille and J. M. Doyle and M. D. Lukin and R. J. Schoelkopf and P. Zoller},
journal= {arXiv preprint arXiv:quant-ph/0604140},
year = {2009}
}