[Reading Science] Fatal Calculation Errors in Quantum Computers... Found the 'Key'

KIST Researchers Develop World-Class Quantum Error Correction Technology
Lagging Behind Big Tech in Quantum Computer Development but Matching in Error Correction

Quantum computers are a groundbreaking technology capable of solving all existing computational challenges. However, their superior computational power comes with a double-edged sword: computational errors. Solving the error problem is essential for the practical application of quantum computing technology. Domestic researchers have attracted attention by announcing achievements on par with leading global quantum computer companies.

◇ Slower speed but superior error correction = On the 29th of last month, Dr. Seungwoo Lee's team at the Quantum Technology Research Group of the Korea Institute of Science and Technology (KIST) announced that they developed world-class quantum error correction technology and designed a fault-tolerant quantum computing architecture based on it. Using this technology, they also demonstrated results that surpass the performance of the quantum error correction technology recently developed by PsiQuantum, a leading company in universal quantum computer development in the United States.

Lee Seung-woo KIST Researcher

The basic unit of quantum computation, the qubit, differs from traditional computers by representing information not as 0 or 1 but as a superposition of values between 0 and 1, enabling performance beyond conventional computers.

The problem is that input information quickly degrades, and errors easily occur. No matter how much the accuracy of error occurrence and control in qubits is improved, as the system size and computational scale increase, accumulated errors prevent the computer from functioning properly. The solution to this is 'quantum error correction.' No matter how high the qubit performance is, if the error rate is high, it is useless. This is why major countries and companies leading quantum computing development focus on developing quantum error correction technology while trying to improve performance.

The performance of a universal quantum computer performing quantum error correction is evaluated by the maximum fault-tolerance threshold. This threshold indicates how well errors occurring in quantum computing can be corrected, and the better the error correction technology and architecture design, the higher the value.

PsiQuantum is developing a quantum computer using photonic entanglement resources, fusion techniques, and error correction technology. The maximum photon loss threshold for the PsiQuantum method has been reported as 2.7%. The new error correction method developed by the KIST research team shows significantly superior performance compared to PsiQuantum.

KIST's technology can achieve a maximum photon loss threshold of up to 14%. This is the highest threshold value currently worldwide. Additionally, KIST's error correction method demonstrated much better resource efficiency than the PsiQuantum method with the same photon consumption.

This research is an achievement by a purely domestic research team, marking an important milestone that South Korea, a latecomer in the quantum computing field, has developed world-class core technology. This result stands out even more given the prevailing assessment that domestic quantum technology lags significantly behind advanced quantum countries. While major overseas companies have reached performance levels of around 1000 qubits, South Korea is now challenging the achievement of 20 qubits.

President Yoon Suk-yeol is visiting the 'Quantum Korea 2023' exhibition hall after attending the 'Dialogue on the Present and Future of Quantum Science and Technology' held at Dongdaemun Design Plaza (DDP) in Seoul in June last year, examining a model of a 50-qubit superconducting quantum computer developed by the Korea Research Institute of Standards and Science. Photo by the Presidential Office Press Photographers Group [Image source=Yonhap News]

Minister of Science and ICT, Sang-im Yoo, has expressed concern that among the three major game-changing technologies, quantum is the most worrisome, reflecting the still low expectations for the domestic quantum field. This could become a 'counterpunch' that overturns such concerns.

Quantum error correction technology is essential not only for photon-based quantum computers but also for qubit development in superconducting, ion trap, neutral atom, and other quantum computer platforms. It is a field with extremely fierce global research and development competition.

This achievement has raised hopes for the Korean quantum industry by showing that South Korea can catch up with and potentially surpass leading countries like the United States in quantum technology.

KIST has completed domestic and international patent applications for this achievement. KIST is also expected to play a crucial role in building an independent universal quantum computing system.

Dr. Seungwoo Lee of KIST stated, "Just like semiconductor chip design technology, architecture design is important in quantum computing. Even if there are 1000 qubits, if the structure does not support error correction, performing even a single logical qubit operation is difficult," adding, "While practical quantum computing still requires time, this research contributes to bringing that time closer."

◇ Fierce competition among overseas scholars to secure quantum error correction technology = Recently, global groups and companies leading universal quantum computer development, including Google, AWS, PsiQuantum, Sandu, Harvard University, QuEra, and the University of Tokyo, are all focusing on developing quantum error correction technology.

Professor Mikhail Lukin of Harvard University attracted attention by introducing achievements in a special lecture at 'Quantum Korea 2024,' held in June at KINTEX in Ilsan, Gyeonggi Province, where he demonstrated error correction previously considered impossible in existing quantum computers through research on quantum computers using 'neutral atoms' as qubits.

Professor Lukin's team succeeded in stabilizing quantum information and reducing errors by creating a separate structure called a 'logical qubit' using multiple neutral atoms.

Professor Lukin said, "I believe there will be many improvements in quantum computer performance, control, and error aspects in the future," and added, "Quantum science is a discipline combining pure science and engineering applications," predicting, "Devices with around 100 qubits will be released in the not-too-distant future."