NTHU Researchers Use One Photon in Developing World’s Smallest Quantum Computer
HSINCHU, Taiwan, Nov. 08, 2024 – A research team led by Professor Chih-Sung Chuu of the Department of Physics and the Center for Quantum Technology at National Tsing Hua University (NTHU) in Taiwan has recently announced that it has successfully developed the world’s smallest quantum computer—using only one photon. This is also the first optical quantum computer developed in Taiwan.
Professor Chuu’s research team demonstrated at the press conference that their optical quantum computer, running in an optical fiber loop with only one photon, can process complex mathematical operations, including such prime factorizations as 15 = 5 x 3—the very first time that a single high-dimensional photon has been used to perform quantum algorithms.
The team’s groundbreaking research was published in the September issue of Physical Review Applied.
NTHU president W. John Kao said that the team’s groundbreaking research is a milestone in quantum computers. Last year, he visited the most advanced quantum computer laboratory in the United States, and what impressed him most was the huge cooling system that filled an entire room, keeping the temperature at minus 273 degrees Celsius. However, the optical quantum computer developed at NTHU can operate at room temperature and the device is only the size of a box, prompting Kao to exclaim, “I hope that one day we will all have an optical quantum computer on our desk!”
Chuu explained that photons are elementary particles of light. In order to allow a photon to carry more information, the team developed a technology that can encode information into 32 dimensions on a single photon. As is widely known, a one-dimensional object is a line; a two-dimensional object is a plane with length and width; and a three-dimensional object has length, width, and height. The quantum computer created by Chuu’s team is able to encode information in 32-dimensions, or time bins, within a single photon, breaking the world record.
Chuu likened photons with a 32-dimensional storage capacity to transforming a single-seat bicycle into a 32-seat bicycle.
Chuu further explained that the conventional optical quantum computers require many photons, but photons are generated probabilistically, appearing and disappearing from moment to moment, making it difficult to make multiple photons appear at the same time. This is what turned Chuu’s attention to the possibility of all the information into one photon. The team’s next goal is to find a way to further increase the information capacity of a single photon, so that it can process even more complex quantum operations.
While ordinary computers perform operations by using electricity to transmit data on circuit boards, optical quantum computers use light to transmit data and use quantum mechanics to perform operations. Chuu explained that while ordinary computers use binary digits, or bits, that can only represent either 0 or 1, the quantum bit, or qubit, used in a quantum computer can be both 0 and 1 at the same time. This characteristic is called quantum superposition and enables quantum computers to process complex operations such as prime factorizations and big data searches hundreds of millions of times faster than ordinary computers.
College of Science dean Chung-Yu Mou pointed out that this optical quantum computer is the result of independent research and development sponsored by the Center for Quantum Technology at NTHU, demonstrating the school’s technical strength in quantum technology and its commitment to innovation. Amongst the wide range of future applications for optical quantum computers are the research and development of new drugs, optimizing logistics, and information security. Moreover, since the efficiency of optical quantum computers greatly exceeds that of the supercomputers currently in use, they are expected to have a major impact on the future development of artificial intelligence.
