Quantum control of proximal spins using nanoscale magnetic resonance imaging

Quantum control of individual spins in condensed-matter systems is an emerging field with wide-ranging applications in spintronics(1), quantum computation(2) and sensitive magnetometry(3). Recent experiments have demonstrated the ability to address and manipulate single electron spins through either optical(4,5) or electrical techniques(6-8). However, it is a challenge to extend individual-spin control to nanometre-scale multi-electron systems, as individual spins are often irre-solvable with existing methods. Here we demonstrate that coherent individual-spin control can be achieved with few-nanometre resolution for proximal electron spins by carrying out single-spin magnetic resonance imaging (MRI), which is realized using a scanning-magnetic-field gradient that is both strong enough to achieve nanometre spatial resolution and sufficiently stable for coherent spin manipulations. We apply this scanning-field-gradient MRI technique to electronic spins in nitrogen-vacancy (NV) centres in diamond and achieve nanometre resolution in imaging, characterization and manipulation of individual spins. For NV centres, our results in individual-spin control demonstrate an improvement of nearly two orders of magnitude in spatial resolution when compared with conventional optical diffraction-limited techniques. This scanning-field-gradient microscope enables a wide range of applications including materials characterization, spin entanglement and nanoscale magnetometry.