In recent times, research all over the world has shifted from a state of diversity to Quantum Information Systems (QIS), based on Nanotechnology. QIS is thesynergy of Quantum Mechanics and Information Systems, the two giants in science and technology from the last century.It explain the present state of physical realization of quantum computation devices and their future scope. The book concludes with a note on developing a Theory of Many Things for high-end complexity systems. This book would be a handy reference for researchers, scientists and professionals working in the field. It would also be useful to students of quantum computing and information systems.