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U of Tokyo-led team comes step closer to large-scale quantum computing

  • October 18, 2019
  • , Jiji Press , 3:00 a.m.
  • English Press

Tokyo, Oct. 18 (Jiji Press)–An international research group led by University of Tokyo scientists said Friday they have made an achievement that can lead to the development a large-scale quantum computer.

Quantum computers use subatomic particles, such as electrons and photons, as basic units for quantum calculation called qubits.

Unlike a bit, the basic unit for conventional semiconductor computers, a qubit can do far more calculations much faster.

Current mainstream quantum computers use the “quantum logic gate” circuit, which requires all qubits to be connected to one another. The connections would become complex as the number of qubits increased, limiting the practical application of quantum computers to around 50 qubits.

Akira Furusawa, professor at the university, and colleagues made the qubit connections unnecessary by generating a quantum state called “two-dimensional cluster state” from four squeezed light sources and a linear optical network consisting of five beam splitters and two delay lines.

The cluster state achieved 25,000 qubits, they said, adding that theoretically the size can be expanded unlimitedly.

Details of the project were published online by the U.S. journal Science.

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