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Quantum computing: Japan takes step toward light-based technology

  • December 23, 2021
  • , Nikkei Asia , 2:28 a.m.
  • English Press

AKIRA OIKAWA and AKIHIRO OTA, Nikkei staff writers


TOKYO — A Japanese team of scientists on Wednesday announced a key step in the development of a quantum computer using photons, or particles of light, that eliminates the need for an ultracold environment used to cool existing machines.


The team including Nippon Telegraph and Telephone, the University of Tokyo and Japan’s Riken research institute has developed a high-performance source of “squeezed light” used to transmit information in optical quantum computing.


The goal is to develop a powerful quantum computer using this technology by 2030.


The public-private-academia effort marks a significant stride for Japan in an area that is expected to be vital for competition in a wide range of industries in the coming years. The government provided funding for the project as part of a 200 billion yen ($1.76 billion) initiative.


The field has largely been dominated by the U.S., thanks to tech giants such as Google and IBM, as well as by China, which is also at the forefront.


The research team sees the potential for vastly improved performance over competing technologies. “It’s a paradigm shift,” said project manager Akira Furusawa, professor at the University of Tokyo School of Engineering.


Optical computers can run at room temperature, without the expensive cooling equipment needed for other quantum computers that use superconductors.


NTT, which offers fiber-optic internet service in Japan and has continued to research optical technology, leveraged its experience and expertise in the field for this project.


The team including Nippon Telegraph and Telephone has developed a high-performance source of “squeezed light,” which is needed for optical quantum computing.(Photo by Daiki Hiraoka)

Quantum computers can handle calculations that conventional systems cannot. Google announced in 2019 that it had achieved “quantum supremacy” by completing in just over three minutes a task that would take the best classical supercomputers 10,000 years. Companies and research institutions around the world have joined the race.


Google and IBM are working with superconducting quantum computers, which use materials that have zero electrical resistance at ultralow temperatures. In Japan, Riken and Fujitsu are taking this route as well.


The technology is advancing, with IBM announcing last month the development of a processor with 127 quantum bits, or qubits — more than the 53-qubit system with which Google claimed quantum supremacy.


But there are certain hurdles, such as wiring, that make it difficult to improve the performance of superconducting systems, and other players are pursuing alternative possibilities.


Hitachi is working on a silicon-based quantum computer, seen as a promising avenue for large-scale systems in the future. U.S.-based IonQ uses trapped ions within a vacuum chamber.


Each of the available methods has advantages and disadvantages. The merits of optical systems include the potential for scalability and reduced power usage. China’s University of Science and Technology said last year it had achieved quantum supremacy with a light-based computer.


Boston Consulting Group estimates that quantum computing will create $850 billion in annual value by 2040. While many challenges remain, such as dealing with errors caused by noise, the advances being made on multiple fronts could speed up the introduction of quantum technology into practical use.

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