Measuring Quantum Communication States 5 Times More Accurately Using Machine Learning Technology

Senior Researcher Sangmin Lee of the Standard Science Research Institute and Others: "World's Highest Level Accuracy"

Lee Sang-min, Principal Researcher at the Korea Research Institute of Standards and Science, conducting a quantum state evaluation experiment. Photo by Korea Research Institute of Standards and Science

[Asia Economy Reporter Kim Bong-su] The Korea Research Institute of Standards and Science (KRISS) announced on the 25th that a joint research team led by Senior Researcher Lee Sang-min has developed a technology to evaluate the qubit state, the unit of information used in quantum communication and quantum computing, achieving world-class accuracy.

A qubit is information stored in fundamental quantum particles such as atoms and photons, allowing superposition of 0 and 1, which enhances information security and enables large-scale information processing in some cases. It is the basic unit of information used in quantum cryptography communication and quantum computing.

Quantum state precision measurement technology is a core technology for verifying the reliability of quantum information technology. It can be widely applied in the quantum information technology industry, including quantum cryptography communication.

In quantum information technology, measurement itself is part of the information processing. The act of measurement affects the quantum state being measured, and this interaction is utilized in the computation process of quantum computers or quantum communication. Inaccurate measurement causes information errors, and applied technologies cannot achieve their original purpose.

Research to precisely measure quantum states has been continuously conducted. However, due to the nature of quantum technology that directly measures quantum mechanical particles such as atoms or photons (photon: the basic unit of light with minimum energy), the number of measurement targets is limited, restricting precision.

Recently, machine learning methodologies have been used to improve this. Most previously proposed studies used a method of measuring quantum particles step-by-step to estimate specific values. To update information step-by-step, a relatively large amount of continuous data updates are required. This necessitated a time-consuming computational process.

The research team developed a machine learning methodology that uses a much simpler rule than existing methods, requiring almost no time. They experimentally demonstrated that single-photon qubit measurement is possible with theoretically optimal resource efficiency and accuracy (<10^-5) that existing technologies have not achieved. This accuracy is at least five times better than previous results.

Schematic diagram and experimental setup of resource-efficient quantum state precision measurement using single-shot measurement and learning.

This technology can be applied to the real-time alignment and calibration of the reference axes of the transmitter and receiver in satellite quantum cryptography communication. Quantum communication used in space satellites transmits quantum information using the polarization of photons, and inaccuracies in reference axis alignment can reduce the cryptographic key distribution rate or make distribution impossible. The technology developed by the research team can perform fast optical alignment without complex calculations, solving these problems.

Senior Researcher Lee Sang-min said, “This research result is expected to contribute to the practical speed improvement of quantum application technologies such as the optimization of quantum communication devices.”

The research results were published online on the 30th of last month in the international physics journal Physical Review Letters (IF: 8.385).

This content was produced with the assistance of AI translation services.