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1Introductionere have been, and will continue to be startling evolutions in information communication technologies almost on a daily basis, On the other hand, it has been pointed out that they may hit performance limitations sooner or later if conceived on the basis of conventional technological systems and their extensions. Ensuring secu-rity is the challenge of utmost importance in the rapidly expanding current-day communication networks — from land-based optical ber networks to satellite communica-tions — and encryption is the key for security. However, it has been pointed out that the encryption schemes cur-rently in use may fall victim to the decoding power of future computer technologies. In other aspects, physical upper limits of the laser power injectable into optical ber will make it harder to cope with the ever-increasing volume of communication trac, and, on the ipside, lower limits of feeble signal identication set the threshold to the pos-sible range of ultralong distance communication — typi-cally communication with planetary exploration spacecra.Against these odds, a series of predictions have been made in recent years that may provide breakthrough technological innovations. Namely, quantum information technology can pave the way for the realization of such realms as: quantum cryptography that provides levels of security unattainable through conventional technologies, quantum computers that crunch problems that would take thousands of years if conventional computers were em-ployed, and quantum receiving techniques that can make the ultimate physical limits of communication volume a reality. Quantum information technology (QIT) takes ad-vantage of cutting-edge quantum physics theories that ex-plain the microscopic behaviors of atoms, electrons and photons. Since the advent of the 21st century, serious re-search and development has been underway toward realiza-tion of the technology worldwide. NICT has been promoting research toward realization of quantum infor-mation technologies placing special focus on their com-munication aspects — i.e. Quantum Information and Communication Technology (QICT). is report overviews the current status of research and development in NICT.2Quantum photonic network technologyCryptography is used in various scenes in our modern society. However, it has been constantly warned that the current cryptographic methods may be vulnerable to de-cryption if some innovation takes place in the future in the art of computing. e concern stems from the fact that the security of soware-based modern cryptography depends heavily on the intensive computation required to decrypt the encrypted message (so-called “computational security”). For example, the RSA cryptosystem — one of the repre-sentative techniques in modern cryptography — is built on the rationale that modern computers consume too much time to factorize a large number into prime factors. However, rapidly growing computing power and an inven-tion of an innovative prime factorization algorithm may enable a computer system to solve the problem in a reason-ably manageable timespan in the near future. It is already in our knowledge that realization of quantum computing, computing technology that takes advantage of quantum characteristics, can crunch the RSA code easily and quickly. e situation poses serious threats to such areas as national intelligence, nancial and medical information 2 Quantum Info-Communication Technology -Overview-Masahiro TAKEOKA, Kouichi SEMBA, and Masahide SASAKICurrent information and communications technology was designed based on physical laws established in the 19th century, and issues regarding transmission capacity and security of encryptions are prompting concern that we will reach the limits of these laws in the future. To overcome such limitations, NICT is conducting R&D on quantum information and communication technology, new technology based on quantum mechanics, the ultimate physical laws, and applications of this technology. We give an overview of this work below.52 Quantum Info-Communication Technology -Overview-