Figure 5: Characterization of the two-qubit system.
From: Demonstration of entanglement-enhanced phase estimation in solid
(a) NV centre with a nearby 13C nuclear spin. (b) 2D fluorescence scan of the FIB-etched solid immersion lens (SIL, 12 μm diameter). The bright spot is the investigated NV centre. (c) ODMR of NV electron spin under magnetic field of 690 Gauss. The splitting is caused by the nearby 13C nuclear spin. (d) Rabi oscillation and free-induction decay (FID) of electron spin (B=507 Gauss). Due to the thermal fluctuation of the spin bath, centre electron spin picks up random phase during free precession and loses coherence. With the help of resonant MW pulses, electron spin can be flipped in short time, and is less affected by the bath noise.
