For “the age of quantum information science in the 21st century”

Professor Hiroshi Imai
(Department of Computer Science)

Professor Imai' s challenge is to establish a quantum information model based on the view that “the age of quantum mechanics will begin in the middle of the 21st century.” He led the successful quantum cryptography communication experiment that guaranteed security for the first time in the world in 2007, a quarter-century after it was first proposed in 1984. The experiment leveraged his unique algorithm using “decoy” to send information without being eavesdropped.

Quantum behaviors would significantly change computer and communication. A quantum computer would have dramatically increased speed, and it is expected that it would compute the prime factorization of an integer in a day, while even the fastest supercomputer would take more than a half-year. Professor Imai views that “quantum information processing”, which uses untraditional mechanics and principles, was waiting in front of researchers in information science and technology as a new research field when limitations in the world of “0” and “1” surfaced and progress of computer science seemed to come to an end.

Although he conducts research on diverse topics such as algorithm theory, his current focus is quantum cryptography communication. According to the uncertainty principle in quantum mechanics, a quantum state changes if measured. This principle is highly effective in quantum cryptography communication, and Professor Imai proved the feasibility of secure communication by connecting ordinary office environments without being eavesdropped, using decoy information.

Information science and technology infrastructure needs to be built for quantum computer and quantum communication to play an active role in 50 years from now. Professor Imai has been working on quantum information system research, including quantum communication systems, quantum computation mechanisms, and quantum information system architecture for two terms of five years starting in 2000. He says ”what interests me about information science research is that, by embodying what is in your mind, things that were impossible before become possible.” The quantum age is already visible to Professor Imai' s eyes.