Spin-strain coupling in nanodiamonds as a unique cluster identifier

Abstract

Fluorescent nanodiamonds have been used to a large extent in various biological systems due to their robust nature, their inert properties, and the relative ease of modifying their surface for attachment to different functional groups. Within a given batch, however, each nanodiamond is indistinguishable from its neighbors and, so far, one could only rely on fluorescence statistics for some global information about the ensemble. Here, we propose and measure the possibility of adding another layer of unique information, relying on the coupling between the strain in the nanodiamond and the spin degree-of-freedom in the nitrogen-vacancy center in diamond. We show that the large variance in axial and transverse strain can be encoded to an individual radio frequency identity for a cluster of nanodiamonds. When using single nanodiamonds, this unique fingerprint can then be potentially tracked in real-time in, e.g., cells, as their size is compatible with metabolism intake. From a completely different aspect, in clusters of nanodiamonds, this can already serve as a platform for anti-counterfeiting measures.

Quantum sensing of electric field distributions of liquid electrolytes with NV-centers in nanodiamonds

“…Frequency contributions generated by electric fields E as well as strain Π within the diamond lattice are considered through [32]. The constant offset in the total electric field contributions ξ ⊥ and ξ z as generated by the strain is different for each individual nanodiamond and can, for instance, be determined through ODMR (optically detected magnetic resonance) measurements [33]. β z = γ e B z with γ e = 28 GHz T −1 [34] describes contributions due to axial magnetic fields.…”

“…Besides having a decreased contrast for β z ̸ = 0, the frequency β 2 z + ξ 2 ⊥ of the FID-oscillations depends on both axial magnetic and transverse electric fields. It is therefore needed to perform the measurements in a magnetically shielded environment, for example by a µ-metal as in [33,38]. In the following it will be assumed that all measurements are performed without any magnetic field being present.…”