Conceptual Diagram of Quantum Distance Measurement (Image provided by Professor Kim Geun-soo of Yonsei University)
SEOUL, June 6 (Korea Bizwire) — In a scientific breakthrough with wide-ranging implications for quantum computing and sensing, South Korean researchers have developed the world’s first method for directly measuring “quantum distance,” a fundamental metric in quantum mechanics.
The Ministry of Science and ICT announced Thursday that research teams led by Professor Kim Geun-soo of Yonsei University and Professor Yang Beom-jung of Seoul National University successfully measured quantum distance among electrons in solid-state material. Their findings were published in the latest issue of the journal Science.
Quantum distance is a numerical value that quantifies how similar or different two quantum states are — with values ranging from 0 (identical) to 1 (completely different). Unlike conventional distance, this concept plays a critical role in assessing the precision of quantum computations and tracking the evolution of quantum states.
Until now, global attempts to measure quantum distance have been limited to indirect estimations. The Korean research marks the first successful direct measurement — a development that could enhance the accuracy and reliability of emerging quantum technologies.
On June 5, Professor Kim Geun-soo of the Department of Physics at Yonsei University speaks at the Ministry of Science and ICT press room in the Sejong Government Complex, announcing the development of a method to measure “quantum distance” — a numerical way to quantify distances in the microscopic world smaller than atoms, down to one-millionth the thickness of a human hair. The groundbreaking study, jointly conducted by Professor Kim’s team at Yonsei University and Professor Yang Beom-jung’s team at Seoul National University, marks the world’s first successful measurement of quantum distance among electrons in solid materials. The findings were published in the prestigious international journal Science on June 6 (2:00 p.m. EDT, June 5 local time). (Photo provided by Yonhap)
The teams achieved this by combining theoretical advancements from Professor Yang’s group with experimental innovations from Professor Kim’s lab, which used black phosphorus — a simple two-dimensional material ideal for isolating quantum properties.
Professor Yang’s team discovered that the quantum distance of electrons in black phosphorus is determined by the phase difference of their quantum waveforms. Professor Kim’s team then validated this with an advanced technique using synchrotron radiation and angle-resolved photoemission spectroscopy (ARPES) to extract measurable signal differences linked to those phase shifts. The results closely matched theoretical predictions.
“This is akin to how precise distance measurements are essential for safe architecture,” Professor Kim said at a press briefing in Sejong. “Accurate quantum distance measurement is just as crucial for developing error-free quantum technologies.”
He added that the study’s significance also lies in demonstrating that not just the phase but also the geometry of electrons matters — a concept rarely explored in solid-state physics. “Differentiating the fundamental properties of matter through geometry opens an untapped frontier,” Kim said. “South Korea must become a first mover in this field to advance its standing in global physics research.”
The discovery is expected to serve as a foundational tool across quantum industries and could accelerate advancements in next-generation quantum computing, secure communication, and ultra-sensitive quantum sensors.
Kevin Lee (kevinlee@koreabizwire.com)
