Removing Non-Size-Dependent Electron Spin Decoherence of Nanodiamond Quantum Sensors by Aerobic Oxidation

Abstract

Surface oxidation of nanodiamonds (NDs) is a primary step of their surface functionalization that is key to the success of their recent emerging applications in nanoscale quantum sensors in biological samples. Here, we investigate how the electron spin coherence of single nitrogen vacancy centers in NDs is extended by two major oxidizing techniques, that is, aerobic oxidation and anaerobic triacid oxidation with various processing parameters. Aerobic oxidation at 550 °C most effectively oxidizes the surface and extends T 2 by a factor of 1.44 ± 0.33 to the original NDs. The ND size dependence of this T 2 extension shows that aerobic oxidation removes a constant decoherence contribution irrespective of the ND size, which clearly separates its origin from the surface-derived decoherence sources. The present results highlight the presence of the ND-specific decoherence sources other than surface termination spin noise and spin-active impurities, thereby improving the spin coherence of ND quantum sensors.

Tailored nanodiamonds for hyperpolarized C13 MRI

“…The logical next step is to investigate fine-tuning the concentration and distribution of P1-center defects in a high-purity nanodiamond free from significant quantities of other defect sites. The high-pressure-high-temperature diamond growth conditions that yield specific concentrations of paramagnetic defects are well understood and we anticipate that surface cleaning techniques such as those we have applied here will play an important role in eliminating undesirable surface defects [38,39]. The surface treatment techniques used here will also impact The maximum polarization percentages quoted are the values extracted from fits to polarization build up curves measured at 4.5 K, 2.89 T, such as those shown in Fig.…”

Temperature dependence of the longitudinal spin relaxation time T1 of single nitrogen-vacancy centers in nanodiamonds

“…Shedding light on the spin relaxation processes at stake for NV centers in nanodiamonds, our work opens a way to a better understanding of the origin of diamond surface impurities. Ultimately, the influence of these impurities on the relaxation could be reduced using surface cleaning techniques [31] or could be compensated using quantum control protocols [32].…”

Chemical Functionalization of Nanodiamonds: Opportunities and Challenges Ahead

“…[26] On the contrary,recent research unveiled that surface oxidation of NDs is capable of extending the transverse spin-coherence time (T 2 )o fN -V centers,w hich dictates the spin-memory time in quantum devices and the sensitivity of quantum sensing. [65] Taking into account the different preparation methods and the broad range of surface modifications that can be applied to NDs,w ee xpect that these materials will find more and more uses in materials science and biomedicine.T he use of both core and surface is expected to be synergized in future applications of NDs.…”