Decoherence Imaging of Spin Ensembles Using a Scanning Single-Electron Spin in Diamond

January 29, 2015
Fig. 1

Figure 1: Detecting surface electron spin ensembles using a scanning magnetometer composed of a single nitrogen-vacancy (NV) spin. (a): Schematic of the experiment. The NV spin resides in a nanopillar fabricated on a diamond scanning platform, with distance d from the sample surface. The angle between the normal direction of the surface and the quantization axis of the NV spin θ is imposed by crystallographic directions. The NV spin is optically initialized and read out from above. A nearby antenna is used to apply microwave pulses to manipulate the NV spin state coherently. The diamond sample contains a mesa that is 200 nm in diameter and 50 nm in height, with paramagnetic impurities on the surface. The NV spin is decohered by both the surface spins on the nanopillar and on the sample. [from L. Luan, M.S. Grinolds, S. Hong, P. Maletinsky, R.L. Walsworth & A. Yacoby, "Decoherence imaging of spin ensembles using a scanning single-electron spin in diamond," Scientific Reports 5:8119 | doi:10.1038/srep08119. Reprinted by permission from Macmillan Publishers Ltd: Scientific Reports ©2015.

Professors Amir Yacoby and Ronald Walsworth with colleagues from Harvard, University of Texas, Austin, and University of Basel, Switzerland, published a new articleon decoherence imaging of spin ensembles using a scanning single-electron spin in diamond in Scientific Reports. The nitrogen-vacancy (NV) defect center in diamond has demonstrated great capability for nanoscale magnetic sensing and imaging for both static and periodically modulated target fields. However, it remains a challenge to detect and image randomly fluctuating magnetic fields. Recent theoretical and numerical works have outlined detection schemes that exploit changes in decoherence of the detector spin as a sensitive measure for fluctuating fields. In this article, the physicists describe experimentally monitoring the decoherence of a scanning NV center in order to image the fluctuating magnetic fields from paramagnetic impurities on an underlying diamond surface. They detect a signal corresponding to roughly 800 μB in 2 s of integration time, without any control on the target spins, and obtain magnetic-field spectral information using dynamical decoupling techniques. The extracted spatial and temporal properties of the surface paramagnetic impurities provide insight to prolonging the coherence of near-surface qubits for quantum information and metrology applications.