2021 年 56 巻 2 号 p. 73-81
A quantum internet will provide arbitrary accessibility of distributed quantum systems, enabling secure communication, quantum computing, quantum sensing, etc. The quantum link between distant systems is established by photons flying through optical fibers and satellites. In this review, I present fundamental methods to send, manipulate and detect photonic quantum states to build a quantum internet; especially, technologies related to superconducting photon detectors.