  Nanomechanical resonators with ultra-high quality factors have become a
central element in fundamental research, enabling measurements below the
standard quantum limit and the preparation of long-lived quantum states. Here,
I propose that such resonators will allow the detection of electron and nuclear
spins with high spatial resolution, paving the way to future nanoscale magnetic
resonance imaging instruments. The article lists the challenges that must be
overcome before this vision can become reality, and indicates potential
solutions.
