The Korea Institute of Science and Technology (KIST), in cooperation with major institutions in Korea, has developed "quantum–classical hybrid computing" technology that uses quantum computers together with conventional computers, the first in the world. The research team plans to use this technology to develop new materials, including catalysts that produce hydrogen.
Lee Jin-hyung, head of the Materials Innovation Quantum Simulator Project Group and a professor in Hanyang University's Department of Physics, said at a research results seminar held on the 18th at KIST's Seoul headquarters in Seongbuk-gu, Seoul, "There are cases where a quantum computer can calculate faster than a classical computer, but for most tasks classical is still far more efficient," adding, "We improved efficiency by using a quantum computer only for the parts that are hard to compute classically, and using a classical computer for the rest."
Quantum computers are known as "dream computers." In quantum mechanics, which governs the microscopic world, matter can exist not as one state but as several superposed states, vastly increasing computational power. Conventional computers represent the absence or presence of an electron as 0 and 1, that is, in 1-bit units. By contrast, the unit of a quantum computer is the qubit, in which the 0 and 1 states are superposed.
If a conventional computer has 2 bits, it can be one of four states—00, 01, 10, or 11—but 2 qubits can realize all four at the same time. If there are 300 qubits, 2 to the 300th power states—more than the number of atoms in the universe—are possible, dramatically boosting computing capability. However, error rates are still high and performance is limited, so there are constraints on standalone use.
The project group solved the challenge of predicting and designing material properties that are hard to compute on conventional computers by using "hybrid computing," which combines a quantum simulator with a classical computer. A quantum simulator is a device that performs calculations by emulating quantum phenomena like an actual quantum computer.
Hybrid computing, for example, divides tasks between calculations that classical excels at and those that quantum excels at, and the two systems communicate bidirectionally to solve a single problem together. This enables fast and accurate execution of complex computations.
The research method was also validated through the development of a hydrogen catalyst. This approach can be used in future for other new materials and drug discovery. In particular, by using a domestically produced photonic integrated circuit–based quantum simulator, the team expects to reduce reliance on overseas technology and raise technological self-sufficiency.
Launched in 2023, the project group includes 284 experts in quantum science, chemistry, electronic engineering, computer science, and mathematical statistics from 20 institutions nationwide, including the Korea Institute of Science and Technology (KIST), the Korea Institute of Science and Technology Information (KISTI), the Korea Research Institute of Standards and Science (KRISS), Kumoh National Institute of Technology, and Chonnam National University.
The current research is being conducted at the few-qubit level, and in the second phase the scale will expand to the tens-of-qubits level, enabling larger molecular calculations and reaction predictions.
Director General Lee said, "This study is significant in that it verified the practical viability of using quantum computers," adding, "We will not only develop new materials, including catalysts for hydrogen production, but also confirm and apply the usefulness of quantum computers in a wide range of fields going forward."