最近,我前室友魏朝晖和韩永建合作完成了一篇论文,讨论了单向量子计算的噪声阈值。结果非常有意思,对单向量子计算很有参考价值。首先,把探测器的效率阈值降低到50%。其次,最关键的是对纠缠源的效率不再做限制了,任意低的纠缠效率都可用。这个工作他们做了2年,几经波折,不过最终还是完成了。
Improving noise threshold for optical quantum computing with the EPR photon source
Z.-H. Wei, Y.-J. Han, C. H. OH, L.-M. Duan
We show that the noise threshold for optical quantum computing can be significantly improved by using the EPR-type of photon source. In this implementation, the detector efficiency is required to be larger than 50%, and the source efficiency can be an arbitrarily small positive number. This threshold compares favorably with the implementation using the single-photon source, where one requires the combined efficiency . We discuss several physical setups for realization of the required EPR photon source, including the photon emitter from a single-atom cavity.
原来在我隔壁实验室的Rui Zhang去哈佛做博后跟着Hau所做的一个工作,把光脉冲信息相干的储存在BEC中超过1秒钟,并把光能量的储存效率提高了两个量级,物理世界上对此也有报道。
Z. -H. Wei, Y. -J. Han, C. H. OH, & L. -M. Duan (2009). Improving noise threshold for optical quantum computing with the EPR photon source arXiv arXiv: 0912.1493v1
Zhang, R., Garner, S., & Hau, L. (2009). Creation of Long-Term Coherent Optical Memory via Controlled Nonlinear Interactions in Bose-Einstein Condensates Physical Review Letters, 103 (23) DOI: 10.1103/PhysRevLett.103.233602