Precision sensing, and in particular high precision magnetometry, is a central goal of research into quantum technologies. For magnetometers, often trade-offs exist between sensitivity, spatial resolution, and frequency range. The precision, and thus the sensitivity of magnetometry, scales as 1/T2 with the phase coherence time T2 of the sensing system playing the role of a key determinant. Adapting a dynamical decoupling scheme that allows for extending T2 by orders of magnitude and merging it with a magnetic sensing protocol, we achieve a measurement sensitivity even for high frequency fields close to the standard quantum limit. Using a single atomic ion as a sensor, we experimentally attain a sensitivity of 4.6 pT/Hz for an alternating-current magnetic field near 14 MHz. Based on the principle demonstrated here, this unprecedented sensitivity combined with spatial resolution in the nanometer range and tunability from direct current to the gigahertz range could be used for magnetic imaging in as of yet inaccessible parameter regimes.
Bibliographical noteFunding Information:
This work was supported by the Career Integration Grant (CIG) IonQuanSense, the Israel Science Foundation (Grant No. 039-8823), by the Bundesministerium fur Bildung und Forschung (FK 01BQ1012), an Alexander von Humboldt Professorship, the EU Integrating Projects DIADEMS and SIQS, the EU STREP projects EQUAM and iQIT, and the ERC Synergy grant BioQ.
© 2016 American Physical Society.