Photo of Shuntaro Takeda

Computer & electronics hardware

Shuntaro Takeda

An original loop-based optical circuit has been invented, along with a successful proof of concept.

Year Honored

The University of Tokyo


The race to develop quantum computers is intensifying. These next-generation computers are expected to have applications in a wide range of fields, from drug discovery to AI. There are many methods being studied for building quantum computers, including superconducting circuits, ions, and semiconductors. Optical Quantum Computing, which uses photons for calculations, is one such method. However, all of these methods are hampered by technical issues preventing them from being used on a large scale.

Shuntaro Takeda has overturned the conventional wisdom that large-scale optical quantum computers require large-scale optical circuits with his original idea of loop-based optical circuits, and has succeeded in a proof of concept. The results are a breakthrough that will enable rapid progress in scaling up optical quantum computers by significantly reducing resources and costs necessary for development.

Since photons are highly resistant to disturbances, they have the advantage of not needing cooling or vacuum equipment, which are required for other methods of developing quantum computers. However, in order to do the calculations, quantum teleportation circuits need to be placed along the path of the photons. Therefore, in order to perform calculations at the scale required for practical applications, a large number of blocks of quantum teleportation circuits have to be prepared. By creating a loop-based quantum teleportation circuit, and using the same circuit repeatedly while switching its functions, Takeda designed a method to use the smallest possible quantum teleportation circuit to perform calculations, and thereby also succeeded in developing the optical circuit at the heart of the system.

If an ultra-high speed optical quantum computer operating at room temperature with optical communication functionality can be commercialized, it could become an important part of the infrastructure supporting various industries such as drug discovery, logistics, finance, and IT. Takeda's research results also have the potential to revolutionize society by becoming the base technology for the practical application of various optical quantum information processing technologies such as quantum internet, quantum sensors, and quantum imaging.