Berlin 2014 – wissenschaftliches Programm

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Q: Fachverband Quantenoptik und Photonik

Q 55: Precision measurements and metrology III

Q 55.6: Vortrag

Freitag, 21. März 2014, 12:00–12:15, DO24 1.101

Long spin coherence of nitrogen-vacancy centres in high purity nanodiamonds — Dhiren Kara, •Helena Knowles, and Mete Atature — Cavendish Laboratory, University of Cambridge, Cambridge, UK

The nitrogen-vacancy centre (NV) in diamond provides a highly localised spin-state that can be initialised and probed optically, and coherently manipulated with microwave fields. In addition to quantum information applications, the centre can be used for magnetic field and temperature sensing in a wide range of environments. NVs embedded in nanodiamond crystals are of particular interest for sensing purposes because they can be placed in close proximity to the target and, being bio-compatible, inserted into cells. However, their use has been limited by low sensitivity due to poor spin coherence times.

This talk focuses on measurements performed in ambient conditions on nanocrystals milled from low nitrogen content (50 ppm) bulk diamond, where we are able to extend the free precession time from 0.4 to 1.27 µs by driving dark paramagnetic spin impurities in the lattice into the motionally averaged regime [1]. Further, using dynamical decoupling schemes we achieve a coherence time of 60 µs, an order of magnitude improvement on previous reports. Our results show that these nanodiamonds offer a d.c. and a.c. magnetic field sensitivity of 600 and 140 nT Hz^−1/2 respectively.

[1] H. S. Knowles, D. M. Kara and M. Atature, Nat. Mater. DOI:10.1038/NMAT3805 (2013)