  The limitation of simultaneous measurements of noncommuting observables can
be eliminated when the measured particle is maximally entangled with a quantum
memory. We present a proposal for testing this quantum-memory-assisted entropic
uncertainty relation in a single nitrogen-vacancy (N-V) center in diamond only
by local electronic measurements. As an application, this entropic uncertainty
relation is used to witness entanglement between the electron and nuclear spins
of the N-V center, which is close to the reach of currently available
technology.
