Ramsey Interferences and Spin Echoes from Electron Spins Inside a Levitating Macroscopic Particle

We report on observations of Ramsey interferences and spin echoes from electron spins inside a levitating macroscopic particle. The experiment is realized using nitrogen-vacancy (NV) centers hosted in a micron-sized diamond stored in a Paul trap both under atmospheric conditions and under vacuum. Spin echoes are used to show that the Paul trap preserves the coherence time of the embedded electron spins for more than microseconds. Conversely, the NV spin is employed to demonstrate high angular stability of the diamond even under vacuum. These results are significant steps towards strong coupling of NV spins to the rotational mode of levitating diamonds.

Figure 1

Schematics of the experiment. A charged micron-sized diamond containing NV centers is levitating in a Paul trap. The spin properties of the NV centers are analyzed using confocal microscopy with both oscillating and static magnetic fields. The trap can be operated under vacuum or atmospheric conditions.

Figure 2

(a) Electronic spin resonance spectrum, (b) longitudinal spin relaxation, and (c) Rabi oscillations from NV centers in a diamond monocrystal levitating in a Paul trap under ambient conditions.

Figure 3

(a) (Top panel) Sequence used for measuring Ramsey oscillations with NV centers. (Bottom panel) Ramsey oscillations from NV centers in a levitating diamond measured for three microwave detunings $\mathrm{\Delta }/2\pi$ from the ESR line under atmospheric conditions. (b) Spin-echo sequence and normalized photoluminescence as a function of precession time for the echo sequence [trace (i)] and Ramsey measurements with a resonant microwave tone [trace (ii)].

Figure 4

Spin control of NV centers in diamonds levitating in the underdamped regime. (a) Electronic spin resonance, (b) Rabi oscillations and (c) spin echo, and (inset) Ramsey measurements. All measurements are conducted under about 1 mbar of vacuum pressure.