Princeton University

School of Engineering & Applied Science

Coherent few-spin systems in diamond nanocrystals for quantum sensing

Dr. Helena Knowles, Cavendish Laboratory, University of Cambridge, United Kingdom
Bowen Hall Auditorium
Monday, October 23, 2017 - 12:30pm

Single isolated spins in solids can act as a unit of a quantum network or as an individual magnetic or electric field sensor. Such a unit can be expanded by using coherently interacting spin clusters, which provide a performance enhancement for quantum technologies.
I this talk, I will show how we investigate hybrid spin systems composed of the Nitrogen Vacancy centre (NV) in diamond coupled to dark spins, i.e. spins that are not directly optically accessible. Both electronic and nuclear dark spins offer distinct advantages: Nuclear spins provide a robust memory for quantum states and electronic spins allow for fast dipole-mediated interactions1,2.

The access to nuclear spins in diamond nanocrystals has so far remained elusive but, as we demonstrate, can provide important sensitivity enhancements for NV centre-based sensing, as NVs in nanodiamond typically have short coherence times (~μs) compared with their bulk counterparts (~ms)2. We also make use of a proximal nitrogen (N) impurity cluster to perform environment-assisted sensing: An entangled state of the NV and N spins is used to detect an external magnetic field and we observe a double-frequency component in the interferometer signal, corresponding to the contribution of at least two electronic spins, in contrast to the NV spin only.

[1] Knowles et al. PRL 117 100802 (2016), [2] Knowles et al. PRB 96 115206 (2017)