We experimentally demonstrate an optical controlled-NOT (CNOT) gate with arbitrary single inputs based on a 4-photon 6-qubit cluster state entangled both in polarization and spatial modes. We first generate the 6-qubit state, and then by performing single-qubit measurements the CNOT gate is applied to arbitrary single input qubits. To characterize the performance of the gate, we estimate its quantum process fidelity and prove its entangling capability. The results show that the gate cannot be reproduced by local operations and classical communication. Our experiment shows that cluster states are promising candidates for efficient optical quantum computation.
@article{arxiv.0905.2103,
title = {Experimental Realization of a Controlled-NOT Gate with Four-Photon Six-Qubit Cluster States},
author = {Wei-Bo Gao and Ping Xu and Xing-Can Yao and Otfried Gühne and Adán Cabello and Chao-Yang Lu and Cheng-Zhi Peng and Zeng-Bing Chen and Jian-Wei Pan},
journal= {arXiv preprint arXiv:0905.2103},
year = {2015}
}