Spin of elementary particle is fundamentally quantum mechanical; its existence cannot be derived from classical mechanics and perhaps is the most obvious example showing discreteness of the quantum mechanical observation. Although spin-driven phenomena like bulk magnetism is widely used in modern microelectronic industries, dynamics of many particle spins with access to individual spins is not well-known both theoretically and experimentally.

 With tremendous developments in experimental techniques, studying quantum mechanical coherence of individual spins is becoming possible. Toward building coherently controllable integrated quantum systems, we mainly focus on developing experimental techniques for quantum manipulation and measurement of (1) electron, hole, or nuclear spins in gate-defined quantum dots where spins are confined in artificially fabricated potential wells and (2) electron and nuclear spin registers in defects in solid where the spins are confined in atomic potentials.

 Depending on the system, experimental approach and typical time scale is quite different; on one system spins are manipulated at extremely low temperature (~20 mK) and measured purely by electrical transport method, and on the other system room temperature operation is possible with optical spin detection. However, the main interest of studying coherence and entanglement using spins remains the same, and often same language based on open quantum system dynamics and quantum information are applicable. Specific projects and recent results are described more in detail in the sub sections.