The Secret Even Einstein Couldn't Understand, Korean Scientist Solved It After 100 Years [Reading Science]

Institute for Basic Science Achieves First Experimental Verification of Complementarity Principle Demonstrating Wave-Particle Duality

Quantum computer under development by IBM.

[Asia Economy Reporter Kim Bong-su] After humans uncovered the secrets of the "macroscopic world" through Newton's classical mechanics, they seemed to glimpse the status of a god. However, with the advent of electricity and chemistry, they encountered the wall of the "microscopic world." Classical mechanics could not at all explain why and how electricity produces light and heat, or why various substances mix to create unique properties or classify into different materials. Thus, quantum mechanics (quantum physics or quantum science) emerged about 100 years ago. Quantum mechanics, which studies the movements of nuclei and electrons that make up the smallest physical units (atoms), later became the theoretical foundation of modern science and technology fields such as nuclear and atomic engineering, electronic engineering, and polymer engineering. Yet quantum mechanics remains shrouded in mystery. While there are "concepts," many theories have never been "understood" or verified by anyone. So much so that even quantum physicists say, "No one in the world truly understands quantum mechanics," and "Just shut up and calculate."

Among these, a representative example is the "principle of complementarity," proposed in 1928 by Danish physicist Niels Bohr, which states that electrons possess both particle and wave characteristics. What does it mean to say that something is both a wave and a particle at the same time? Even the most brilliant physicist we know, Einstein, never accepted this theory until his death. Einstein, who laid the foundation of quantum mechanics by proposing the "light quantum" hypothesis in 1905 that light is composed of particles, opposed the so-called "Copenhagen interpretation" presented by Bohr and Heisenberg at the 5th Solvay Conference in 1927, along with Schr?dinger and others.

Einstein argued against the Copenhagen interpretation, which claims that the microscopic world making up the macroscopic world is full of uncertainty determined by probabilities due to quantum superposition and entanglement, and that human "understanding" is impossible. He insisted that "electrons are real" and that the world is a place that can be "understood."

Until now, the physics community has only understood the principle of complementarity qualitatively because there was no technology to measure it quantitatively. Although quantum science has advanced to the point where quantum computers are about to be realized, many concepts remain not fully understood, such as "wave-particle duality and complementarity of quantum objects" and "wave function entanglement of two quantum objects." In particular, the quantitative principle of complementarity forms the basis for understanding the superposition and entanglement of wave functions essential to quantum science.

On the 19th, the Institute for Basic Science (IBS) announced that the research team led by Director Min-Hang Cho of the Molecular Spectroscopy and Dynamics Research Center and Research Fellow Tae-Hyun Yoon succeeded in experimentally verifying the quantum complementarity principle, considered the greatest challenge in quantum mechanics for 100 years. They proposed a new model for the quantitative complementarity of wave-particle duality of quantum objects and experimentally demonstrated it using equipment they developed themselves.

To rigorously verify the principle of complementarity and wave-particle duality, a quantum mechanical composite system capable of measuring wave nature and particle nature separately is required. In other words, devices to generate quantum particles, detectors for the position or path of quantum particles, and measurement devices for interference phenomena created by quantum particles in superposition states must be equipped. Although several composite systems have been theoretically proposed and some experimentally tested, no device has perfectly verified the complementarity and wave-particle duality of quantum objects.

The research team overcame this limitation by developing a new experimental system called the "Entangled Nonlinear Photon Pair Source (ENBS)." Unlike existing measurement systems, the ENBS system can experimentally control the degree of entanglement. This means it is possible to experimentally adjust the wave and particle nature of quantum objects within the framework of complementary relationships.

Through this experiment, the researchers proved not only the mutual correlation between the particle and wave nature of quantum objects but also the existence of a quantitative relationship between the two. This result means that, contrary to Bohr's theory that "the wave and particle nature of quantum particles are mutually exclusive, and only one property can be known by one measuring device," both exclusive properties can be measured by a single device by controlling the degree of entanglement. About 100 years after the principle of complementarity was first proposed, the quantitative relationship of wave-particle complementarity has been measured.

Research Fellow Tae-Hyun Yoon said, "Using the quantum composite system experimental device proposed and verified in this study, we may find clues to solve many quantum mechanical challenges that remain unknown."

Director Min-Hang Cho said, "Richard Feynman, who won the Nobel Prize in Physics in 1965, left the remark that 'the essence of quantum mechanics lies in understanding the double-slit experiment.' Using the newly proposed quantum entanglement device, we plan to study the mysterious properties of quantum mechanics more deeply."

The research results were published online on the 19th in the international journal Science Advances (IF 14.136).

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