Diamond Materials

Diamond Materials for Quantum Application

23. September 2014: The DFG research group FOR 1493 “Diamond Materials and Quantum Applications” goes into its second funding period. FOR1493 is a national research consortium funded by the Deutsche Forsch-ungsgemeinschaft.

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ERC Advanced Grant


Measuring broadband magnetic fields using a hybrid quantum register

In a collaboration with Seagate Technology PLC, we have developed methods to characterize the magnetic fields of hard-disk writers using an atomic scale magnetometer. The results mark a significant increase in spatial resolution compared to established sensors and may enable further miniaturization of recording heads and ultimately increase storage capacities of hard disk drives (HDD).

HDDs store data as permanent magnetization on sectors as small as 20 nm on the recording medium of the hard disk. In order to encode data as magnetization bits the hard disk writer, a nanoscopic electromagnet, has to produce magnetic fields that only affect a single bit while it flies by on the rotating disk. Accordingly, its magnetic field is designed to be strong, fast and especially local. These features are beyond the capabilities of established magnetometers leaving the industry devoid of a suitable research and development tool to further miniaturize their products.

We deployed the nitrogen-vacancy defect center in diamond (NV) as magnetometer to resolve this challenging magnetic field. By scanning the HDD writer of the surface of a diamond we could record its magnetic field optically using a single shallow NV. As the NV is an atomic size point defect our spatial resolution only depends on the positioning of the writer.

Besides introducing quantum metrology to manufacturers of mass consumer products, the work also shows that HDD writers may be a viable control tool for NV related research where its unique features, namely its exceptional field strength (1T), gradient (10 mT/nm) and bandwidth (GHz), enable new experiments in spintronics, quantum information processing and magnetic resonance imaging on the nanoscale.

Measuring broadband magnetic fields on the nanoscale using a hybrid quantum register
Ingmar Jakobi, Philipp Neumann, Ya Wang, Durga Bhaktavatsala Rao Dasari, Fadi El Hallak, Muhammad Asif Bashir, Matthew Markham, Andrew Edmonds, Daniel Twitchen and Jörg Wrachtrup