Experimental realization of a concatenated Greenberger–Horne–Zeilinger state for macroscopic quantum superpositions

Date: 2014-04-20
Authors He Lu, Luo-Kan Chen, Chang Liu, Ping Xu, Xing-Can Yao, Li Li, Nai-Le Liu, Bo Zhao, Yu-Ao Chen and Jian-Wei Pan
Journal No. Nature Photonics 8, 364 (2014)
Abstract The Greenberger–Horne–Zeilinger (GHZ) states play a significant role in fundamental tests of quantum mechanics and are one of the central resources of quantum-enhanced high-precision metrology, fault-tolerant quantum computing4 and distributed quantum networks. However, in a noisy environment, entanglement becomes fragile as the particle number increases. Recently, a concatenated GHZ (C-GHZ) state, which retains the advantages of conventional GHZ states but is more robust in a noisy environment, was proposed. Here, we experimentally prepare a three-logical-qubit C-GHZ state. By characterizing the dynamics of entanglement quality of the C-GHZ state under simple collective noise, we demonstrate that the C-GHZ state is more robust than the conventional GHZ state. Our work provides an essential tool for quantum-enhanced measurement and enables a new route to prepare and manipulate macroscopic entanglement. Our result is also useful for linear-optical quantum computation schemes whose building blocks are GHZ-type states.