World's first 8-photon Schrödinger's cat born

Updated: 2012-02-29 11:59

By Ma Chenguang and Liu Nanxue (

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HEFEI - A group of physicists here in Anhui province, led by China's youngest academician Pan Jianwei, has managed to entangle eight photons in the so-called Schrödinger's cat state for the first time, breaking the previous six-photon world record set up by the same group in 2007.

According to Pan, 42 and an academician from the Chinese Academy of Sciences (CAS), and his colleagues, Chen Yuao and Lu Chaoyang - all from University of Science and Technology of China, the eight-photon state would allow them to demonstrate a powerful way of correcting quantum errors called topological error correction. Pan is also an academician of the Chinese Academy of Engineering.

Professor Lu Chaoyang said on Feb 21 here that developing practical quantum computation heavily depends on the coherent manipulation of multiple quantum states. The full entangled multipartite Schrödinger's cat state is an important benchmark of quantum control.

He noted that simply put, a multi-particle entanglement platform is like an aircraft carrier controlling quantum computing, and by relying on the carrier, a variety of quantum computing research is made possible.

The team has been devoted to the research of the field, withlong-term support from CAS which administers USTC, the Ministry of Science and Technology and National Natural Science Foundation of China.

Professor Lu disclosed that the team will publish another paper entitled Topological Error Correction in the Nature magazine on Feb 23, elaborating on the use of eight photons in quantum error correction.

Wang Qinmou, a professor from Wuhu-based China Normal University, said on Feb 21 that a breakthrough in quantum entanglement - a brand new field - is of vital importance, and its future wide use in quantum communication and biology might even help break the theory of relativity, producing impact on the world's innovation.

In 2004 and 2007, Pan's team succeeded in manipulating the entanglement of five and six photons respectively, with relevant papers published in Nature and Nature Physics. After four years of hard work, the team brought the manipulation of photons to another level, and created the world's best entanglement photon source in terms of brightness and purity.

In early 2011, the team was the first to realize the eight-photon Schrödinger's cat state. The news was published in Nature Photonics, a foreign press, on Feb 12 this year.

Since the release of the preprint at in May 2011, it has attracted widespread attention in the academic community. Many science publishers, such as Institute of Physics, MIT Technology Review, Phys Org have reported the work, noting that “In a game of one-upmanship, a Chinese team of physicists has figured out how to entangle eight photons simultaneously and to observe them in action; the previous record was six” .