Quantum information science and technology has emerged as a fresh paradigm for dramatically faster computation and secure communication in the 21st century. At the heart of any quantum system is the most basic building block,the quantum bit or qbit, which carries the quantum information that can be transferred and processed (this is the quantum analogue of the bit used in current information systems). The most promising carrier qbit for ultimately fast, or long distance quantum information transfer is the photon,the quantum unit of light.
Source: phys.org