We studied and implemented for the first time dynamical decoupling on a single solid-state spin, the spin of a nitrogen-vacancy (NV) center in diamond, and prolonged its coherence time by a factor of 25. Besides its fundamental importance, this achievement constitutes an important advance towards manipulating matter at the level of single spins and opens new possibilities for highly sensitive magnetic sensors, and possibly for qubits for larger scale quantum information processing. Nitrogen-vacancy centers in diamond have unusual magnetic and optical properties with potential uses, but their fragile quantum states are easily destroyed by miniscule interactions with the outside world. Our research team achieved reliable control over the single quantum magnetic moments (spins) of nitrogen-vacancy centers by applying a specially designed sequence of high-precision electromagnetic pulses, and we were able to protect the quantum state of a single spin and make it evolve as if it were completely decouples from the external world. This work is closely tied to the effort within FWP "Nanoscale Structures and Ultrafast Correlations in Magnetic Materials" and is also relevant for the FWP "Solid-state NMR".
Universal dynamical decoupling of a single solid-state spin from a spin bath