Coherent Dynamics of a Single Spin Interacting with an Adjustable Spin Bath

Abstract

Phase coherence is a fundamental concept in quantum mechanics. Understanding the loss of coherence is paramount for future quantum information processing. We studied the coherent dynamics of a single central spin (a nitrogen-vacancy center) coupled to a bath of spins (nitrogen impurities) in diamond. Our experiments show that both the internal interactions of the bath and the coupling between the central spin and the bath can be tuned in situ, allowing access to regimes with surprisingly different behavior. The observed dynamics are well explained by analytics and numerical simulations, leading to valuable insight into the loss of coherence in spin systems. These measurements demonstrate that spins in diamond provide an excellent test bed for models and protocols in quantum information.

Decoherence dynamics of a single spin versus spin ensemble

“…Such variations have been observed, e.g., in experiments on NV centers in diamond. 13,22 Although the number of spins with large b decreases with b, but "one bad apple spoils the barrel:" the effect of such rare S spins with abnormally large value of b ͑much larger than ⌫͒ qualitatively changes the behavior of FID. In practice, it means a "typical" value of b for a single central spin is very weakly determined by the value of ⌫.…”

“…One can think, for instance, of a frequently encountered situation 17,21 where S spins are paramagnetic centers in nonmagnetic crystal and I spins belong to another rare species: e.g., S could be the electron spin of a nitrogen-vacancy center in diamond, and I spins could be a bath of 13 C nuclear spins, 11,14 or the bath of the electron spins of nitrogen atoms ͑P1 centers͒. 22,23 We assume that the S spins are extremely rare ͑as it is the case for impurities in reasonably clean samples͒, so that the coupling between different S spins can be neglected and every spin S can be considered separately ͑see Fig. 1͒.…”

Broadband, large-area microwave antenna for optically detected magnetic resonance of nitrogen-vacancy centers in diamond

“…The factor 1/ √ 2 is due to the rotating wave approximation in the S = 1 spin system. 33,34 Through the CW ODMR measurements we already know the NV axes responsible for the respective resonances [ Fig.4], and the simulation results give the orientation of B 1 [ Fig.2(a)]. They together give β i , allowing us to convert experimental f R into B 1 .…”

Decay of the rotary echoes for the spin of a nitrogen-vacancy center in diamond

“…25,[39][40][41][42][43][44][45][46] At the same time, an alternative approach based on the continuous dynamical decoupling has been extensively investigated. 11,[47][48][49][50][51][52][53][54][55][56][57][58] Within this approach, strong resonant driving is applied to the NV center. The resulting fast Rabi oscillations of the NV spin, similarly to the flip-flops induced by the decoupling pulses, average out the interaction with the environment, and significantly extend the spin coherence time.…”