Bourennane Mohamed, Eibl Manfred, Gaertner Sascha, Kurtsiefer Christian, Cabello Adán, Weinfurter Harald
Max-Planck-Institut für Quantenoptik, D-85748 Garching, Germany.
Phys Rev Lett. 2004 Mar 12;92(10):107901. doi: 10.1103/PhysRevLett.92.107901. Epub 2004 Mar 9.
Decoherence-free states protect quantum information from collective noise, the predominant cause of decoherence in current implementations of quantum communication and computation. Here we demonstrate that spontaneous parametric down conversion can be used to generate four-photon states which enable the encoding of one qubit in a decoherence-free subspace. The immunity against noise is verified by quantum state tomography of the encoded qubit. We show that particular states of the encoded qubit can be distinguished by local measurements on the four photons only.
无退相干态可保护量子信息免受集体噪声影响，集体噪声是当前量子通信和计算实现中退相干的主要原因。在此，我们证明自发参量下转换可用于生成四光子态，该态能在无退相干子空间中实现一个量子比特的编码。通过对编码量子比特的量子态层析成像验证了其抗噪声能力。我们表明，仅通过对四个光子进行局域测量就能区分编码量子比特的特定状态。
