“We can find real examples of quantum mechanics that even Einstein could never accept in our daily lives. Understanding quantum entanglement and quantum mechanics allows us to build a broader understanding of quantum computers, which have endless applications.”
On the afternoon of the 19th at 3 p.m., about 60 high school students gathered in the multimedia room of Hwadong Hall at Gyeonggi High School in Gangnam, Seoul. These students voluntarily attended to hear a special lecture by Lim Ji-su, a distinguished professor in the Department of Nano Semiconductor Engineering at Ulsan National Institute of Science and Technology, who graduated from Gyeonggi High School. As the teacher introduced Professor Lim, highlighting his achievements such as being the top graduate and placing first nationally in college entrance exams, cheers erupted among the students.
Professor Lim chuckled awkwardly and opened a slide titled ‘Understanding quantum entanglement: Einstein's humiliation and quantum computers’. The students quickly became engrossed in his lecture. Quantum entanglement refers to the phenomenon where two quantum pieces of information, even when far apart, influence each other. Because the speed of this influence is faster than light, when the state of one quantum is observed, the state of the other quantum is determined simultaneously. This means that the two pieces of quantum information are entangled regardless of the distance, hence the term quantum entanglement.
Professor Lim explained the complex concept of quantum entanglement, which is difficult for even university students majoring in physics to grasp, by using various examples. The Rubik's Cube is a representative case. On one face of the cube, nine smaller cubes are placed. The number of possible patterns for this cube, which can have different configurations, is about 430 quintillion (1 quintillion is 10 quadrillion). The final pattern, or goal, is to align the surfaces of the smaller cubes of the same color in every direction.
Professor Lim said, “Participants in Rubik’s Cube competitions typically complete the final pattern in 100 steps or less, and the minimum step solution using supercomputers is about 20 steps,” adding that “the Rubik’s Cube moves eight pieces simultaneously with each step, enabling solutions to be drastically expedited through collective computation, allowing answers to be found among 430 quintillion possibilities within 100 steps.”
Quantum computers calculate using 'qubits' where the states of 0 and 1 are superimposed. When the state of a single qubit is determined, the states of other qubits are also determined due to quantum entanglement. This allows for rapid computation without needing to calculate each qubit individually. Professor Lim conveyed the principle of quantum entanglement using the Rubik's Cube, illustrating that when the state of one quantum is determined, the states of other quanta are also determined.
Born in 1951, there was a gap of over 50 years between Professor Lim and the students who attended the lecture that day, yet they were connected through the common ground of physics. A student from Gyeonggi High School said, “Initially, I was puzzled by the idea that information can be confirmed faster than light, but the explanation that information travels like telepathy was so interesting that I felt I wanted to learn more.” Another student noted, “It was great that a professor from Gyeonggi High School came in person to explain the astonishing properties of quantum mechanics, which deviate from common perceptions, using simple analogies.”
On the same day, Professor Kim Geun-soo from Yonsei University’s Department of Physics, also a graduate of the school, visited Seondeok High School in Dobong-gu, Seoul. Despite the late hour of 6 p.m., about 50 Seondeok High School students gathered to hear his lecture. Professor Kim, born in 1982, is only in his mid-40s but has been recognized for his research abilities, being selected as a global lead researcher by the National Research Foundation of Korea.
Professor Kim introduced the principles of quantum computers and also brought up superconductors, which had caused a stir in Korea a few years ago, as a lecture topic. Superconductivity is the phenomenon where electric current flows without any resistance. It was first discovered in 1911 by Dutch physicist Heike Kamerlingh Onnes at a temperature of -269 degrees Celsius. He received the Nobel Prize in Physics in 1923 for this achievement.
High-temperature superconductors are materials that implement superconductivity at room temperature. Scientists have been searching for high-temperature superconductors that operate at even higher temperatures or at room temperature for over 100 years. If commercialized, lossless transmission can occur regardless of distance, leading to an energy revolution. High-performance electromagnets can also be created for use in maglev trains and nuclear fusion power. Notably, this could also expedite the commercialization of quantum computers. Currently, quantum computers operate using superconductors that function at extremely low temperatures.
Professor Kim remarked, “High-temperature superconductors are such a big issue that one could say winning the Nobel Prize in Physics is guaranteed once discovered. I explained to the students what the specific principles are and what fields they could be applied to,” adding, “The interest from the students was so great that after an hour-long lecture, we spent another hour on Q&A.” Professor Kim also visited Yeouido Middle School on the 23rd to give a similar lecture to the students.
He said, “Public lectures are somewhat different from research, so I feel pressure before doing them, but once I begin, I feel like I receive a lot of energy from the students.” He added, “Even though the younger students may not fully understand the specific scientific principles, I can sense their eagerness to learn from the sparkles in their eyes.”
The visits of the two physicists to their alma maters are part of the ‘Physicists Returning to Their Alma Mater’ lecture series, organized by the Popularization Committee of the Korean Physical Society in celebration of the 100th anniversary of quantum mechanics. Dozens of physicists gathered in May to visit their alma maters and meet with students.
Lee Seong-bin, a professor in the Department of Physics at the Korea Advanced Institute of Science and Technology, who serves as the chair of the Popularization Committee for the Korean Physical Society, said, “The physicists visited their alma maters to share the joy of being a scientist and the pleasures of physics with the younger generation,” and noted that “it was a warm time to openly discuss curiosities about science and to empathize and encourage concerns about career paths.”