KAIST announced on the 25th that a research team led by Professor Young-Sik Ra of the Department of Physics has successfully implemented a three-dimensional (3D) quantum entanglement structure—a groundbreaking advancement in the field of quantum error correction.
Quantum computers surpass classical binary bits (0 and 1) by utilizing qubits, which can exist in a superposition of 0 and 1 simultaneously. These qubits exhibit quantum entanglement, meaning their states are interlinked regardless of distance. Such properties enable quantum computers to solve complex problems that are practically challenging for classical computers.
However, as the number of qubits increases, quantum errors grow exponentially, posing a significant challenge to scalability. This has spurred intense global research into error correction techniques for quantum systems.
Existing quantum entanglement has been realized in two-dimensional (2D) structures. But these 2D frameworks have limitations in correcting quantum errors, prompting the KAIST team to explore a novel approach. Using a laser system capable of emitting powerful light in extremely short bursts, the team experimentally implemented a 3D quantum entanglement structure.
By irradiating a nonlinear crystal with a femtosecond laser beam (one-thousandth of a trillionth of a second), the team generated a quantum light source simultaneously in multiple frequency modes and successfully created a three-dimensional quantum entanglement state. The research team explained that it is possible to measure the surrounding quantum error information by measuring each node (point on the graph) of the three-dimensional structure.
Professor Ra said, “This is the first time a 3D cluster quantum entangled state—previously considered extremely difficult to realize—has been experimentally implemented,” adding, “This breakthrough will serve as a crucial stepping stone in the development of fault-tolerant quantum computing.”
The study, with postdoc researcher Chan Roh listed as the first author, has been published in the online edition of the international journal Nature Photonics.