In recent years, Japanese universities and companies have made breakthroughs in quantum sensor technology.
The Q-Leap collaboration is experimenting with a novel photon source for use in sensors, and other projects are using cutting-edge technology to optimize quantum sensors. This article will highlight the unique approaches that have been taken and the successes so far.
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While the Japanese Government has a clear investment strategy for quantum computing, they are yet to incorporate quantum sensors into these plans. With the recent successes in sensor research, it is hoped that quantum sensors will feature in the budget for the next financial year. This would be welcome support for the companies and universities which have already started developing the technology.
The Government still has some involvement with quantum sensors; the Ministry of Education, Culture, Sports, Science and Technology (MEXT) is responsible for Q-Leap. Q-Leap is Japan’s flagship quantum collaboration and has a Quantum Metrology and Sensing division. Most funding comes from corporate investment, but this may change with the government quantum technology plan that will be published soon.
Q-Leap Quantum Metrology and Sensing
Q-Leap Quantum Metrology and Sensing is based at the Tokyo Institute of Technology, though it collaborates with universities and companies across Japan. These partner universities include The University of Tokyo, Yokohama National University, Hamamatsu University School of Medicine, and Tohoku University.
Q-Leap Quantum Metrology and Sensing also receive investment from Hitachi and NEC, two of Japan’s largest technology corporations. The collaboration’s flagship project is called Dia-Q and aims to innovate with sensor systems by using diamonds as a photon source.
One of the possible imperfections that can occur in diamonds is a Nitrogen-vacancy (NV), which occurs when a nitrogen atom replaces a carbon atom in the diamond lattice. This causes a vacancy in the lattice adjacent to the nitrogen atom, and this imperfection is useful because it has a unique emission spectrum.
When a NV is manipulated with a magnetic field and microwave radiation, it can produce spin-coherent photons almost instantaneously. With other photon sources, there is a significant delay between excitement and emission. The NV source can be optimized in ways that other sources cannot, making it incredibly useful for high-fidelity quantum sensors.
The technology developed by the Dia-Q team will be implemented or improved upon by the applied research areas of Q-Leap Quantum Metrology and Sensing. There are currently seven different research areas, each headed by a different Japanese University:
- Using gravity gradient sensors to create earthquake early-warning systems.
- Creating a detector that can count the number of photons in a given state, which could then be used to investigate other quantum systems.
- Reducing spin and optical noise in magnetometers, to create a more precise magnetometer than previously thought possible.
- Developing 2D quantum spectroscopy, which can analyze frequency-correlations to understand complex quantum structures.
- Improving sensors that use entangled photons, specifically infrared absorption spectrometers, by entangling infrared and visible photons.
- Improving production of NV diamonds for use in Dia-Q.
- Creating sensors that can be used to test “quantized inertia,” to find changes in the kinetic energy of particles.
These research areas are in varying stages of completion, but Q-Leap Quantum Metrology and Sensing is optimistic about Dia-Q’s future. If advances continue, researchers hope to apply the technology to other fields, such as diagnostic medicine and precision engineering.
Sumitomo, a large company that invests in a range of products, has begun a partnership with the US-based startup ColdQuanta. ColdQuanta is developing cold atom quantum systems, which are not dependent on the cooling that other quantum systems require. Without the need for cooling, these systems can be made smaller and more portable. Quantum sensors can be built with this technology, and Sumitomo is working to bring these sensors to the Japanese market.
The Japan Aviation Electronics Industry, a Tokyo-based company, is working with Osaka University and the Tokyo Institute of Technology to develop a high-performance quantum gyroscope. This gyroscope uses matter waves instead of light waves to perform measurements of force and promises to be more reliable than traditional gyroscopes.
Matter behaves like a wave at the quantum scale, and these waves have different properties to photons, which makes them susceptible to changes in force. The Japan Aviation Electronics Industry hopes that these gyroscopes will be used in the aerospace industry.
Optical Lattice Clocks
Led by the University of Tokyo, the Optical Lattice Clocks project is a collaboration between six different companies and eight research institutions from across Japan. Optical Lattices are formed when laser beams propagating in opposite directions interfere with each other. Atoms can then be trapped in these lattices to create incredibly reliable atomic clocks.
The researchers believe these optical lattice clocks could become more portable than other atomic clocks and require less maintenance. They aim to connect these clocks via a reliable network so that they can investigate relativistic events.
Photonic-Crystal Surface Emitting Lasers
Photonic-Crystal Surface Emitting Lasers (PCSELs) were invented at Kyoto University in 1999. In the following years, potential applications have been researched, including the use of PCSELs in quantum sensors. This project is another collaboration, with investment from companies such as Mitsubishi Electric, and the contributors believe that PCSEL detectors will become readily available sometime next year.
References and Further Reading
The Science News Ltd. (2022) Quantum Technology Strategy Review Interim Report: The Government announces measures to strengthen WG industrial competitiveness. Science Japan. Available at: https://sj.jst.go.jp/news/202205/n0523-03k.html
MEXT Q-LEAP. (2022) Q-LEAP Quantum Metrology and Sensing. Online. Available at: https://www.qms.e.titech.ac.jp/en/
Sumitomo Corportation. (2022) Partnership with ColdQuanta, a World-Leading Cold Atom Quantum Technology Company. Online. Available at: https://www.sumitomocorp.com/en/jp/news/topics/2022/group/20221102
Kozuma, M. et al. (2017) Development of high-performance gyroscopes with matter waves. JST-Mirai Program. Available at: https://www.jst.go.jp/mirai/en/program/large-scale-type/theme03.html
Katori, H. et al. (2018) Space-time information platform with a cloud of optical lattice clocks. JST-Mirai Program. Available at: https://www.jst.go.jp/mirai/en/program/large-scale-type/theme04.html
Nature Research Custom. (2022) Japan prepares for the next wave of photonics. Nature. Available at: https://www.nature.com/articles/d42473-022-00113-1