Ultra-large-scale quantum entanglement A new era of quantum computer research begins

December 13, 2013

The development of a quantum computer employing a special correlation among quanta, called quantum entanglement, has been the focus of attention for creating the next-generation of ultrafast computers. The key for realization of such a quantum computer is the creation of ultra-large-scale entangled states. However, the largest entangled state generated to date contains only 14 entangled modes.

© Shota Yokoyama, Top: A picture of the experimental setup. Bottom: An image of generated ultra-large scale entanglement. Nodes and links between them represent optical wave packets and entanglement, respectively.

The research group of Prof. Akira Furusawa and graduate student Shota Yokoyama at the Graduate School of Engineering of the University of Tokyo have realized, for the first time, the generation of ultra-large-scale entangled states using a time domain multiplexing method. This scheme enables the generation of an arbitrary large-scale entangled state without expanding the size of the experimental setup by instead using an entanglement generation machine periodically. The generated entangled states have more than 16,000 entangled modes, which is, by three orders of magnitude, the largest entangled state generated to date. This scheme overcomes the biggest problem for the realization of a quantum computer, scalability of entangled state generation. This success opens the door to a new era of quantum computer research. This achievement was published online in Nature Photonics on November 17, 2013 at 18:00 (GMT).

This research was conducted in collaboration with associate Prof. Nicolas C. Menicucci at The University of Sydney in Australia, and partly supported by the Japanese Ministry of Education, Culture, Sports, Science and Technology Project for Developing Innovation Systems.

Press release


Shota Yokoyama, Ryuji Ukai, Seiji C. Armstrong, Chanond Sornphiphatphong, Toshiyuki Kaji, Shigenari Suzuki, Jun-ichi Yoshikawa, Hidehiro Yonezawa, Nicolas C. Menicucci & Akira Furusawa,
“Ultra-large-scale continuous-variable cluster states multiplexed in the time domain”,
Nature Photonics Online Edition: 2013/11/18 (Japan time), doi: 10.1038/nphoton.2013.287.
Article link


Graduate School of Engineering

Department of Applied Physics, Graduate School of Engineering

Furusawa Laboratory, Department of Applied Physics, Graduate School of Engineering

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