Demonstration of quantum sensor exceeding the measurement limit of conventional sensor

Precise data measurement and securing images and videos using highly sensitive sensors are crucial in the era of the Fourth Industrial Revolution. To this end, multiple parameters that change in real time such as the location of an object, temperature, and time should be estimated with high precision, and quantum effects (superposition and entanglement) can help enhance the measurement precision or estimate the parameters that were not measurable with conventional sensors. The research on such quantum sensors along with quantum computer and communication studies are the major application areas of quantum information technology, in which there is fierce competition between the U.S. and China over technological hegemony.

A research team led by Dr. Hyang-Tag Lim from the Center for Quantum Information, Korea Institute of Science and Technology (KIST) demonstrated quantum sensors that can estimate multiple parameters changing in real time with high precision beyond the standard limits.

The KIST research team demonstrated "multi-mode N00N states" where multiple parameters changing in real time can be precisely estimated. The "multi-mode N00N state" was known to show the highest precision in theory, but its demonstration has been highly challenging.

The research team succeeded in demonstrating quantum enhanced multiple-phase estimation by generating multi-mode N00N states, a quantum entanglement state with photon number N = 2 and mode number m = 4 that is applied to an interferometer so that its multiple phase difference can be simultaneously measured with high precision beyond the standard quantum limit.

Dr. Hyang-Tag Lim from the KIST who led this research stated, "Multi-mode N00N states, the key technology of this achievement, will contribute to the further development of quantum sensing as a foundation technique for quantum imaging and sensor networks." He added, "I hope it will also be used in a high-performance quantum microscope and bio-imaging sensors.“

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The Korea Institute of Science and Technology(KIST). Founded as the first multidisciplinary government-funded research institute in Korea, KIST established a national development strategy based on science and technology and disseminated various essential industrial technologies. Now, half a century later, KIST is elevating Korea's status in the field of science and technology through world-leading fundamental technology R&D. Looking to the future, KIST will continue to strive to be a premier research institute, pursuing a brighter future for Korea and all of humanity.

This study was funded by the Ministry of Science and ICT and conducted as a key project of the KIST, the quantum computing technology development project and the basic research project-excellent new research project of the National Research Foundation of Korea, and the quantum cryptography communication integration and transmission technology advancement project of the Institute of Information & Communications Technology Planning & Evaluation Institute. The research results were published in the latest issue of the international journal 「Nature Communications」 (IF: 14.919, JCR(%): 4.795%).