Nanodiamond arrays on glass for quantification and fluorescence characterisation

Abstract

Quantifying the variation in emission properties of fluorescent nanodiamonds is important for developing their wide-ranging applicability. Directed self-assembly techniques show promise for positioning nanodiamonds precisely enabling such quantification. Here we show an approach for depositing nanodiamonds in pre-determined arrays which are used to gather statistical information about fluorescent lifetimes. The arrays were created via a layer of photoresist patterned with grids of apertures using electron beam lithography and then drop-cast with nanodiamonds. Electron microscopy revealed a 90% average deposition yield across 3,376 populated array sites, with an average of 20 nanodiamonds per site. Confocal microscopy, optimised for nitrogen vacancy fluorescence collection, revealed a broad distribution of fluorescent lifetimes in agreement with literature. This method for statistically quantifying fluorescent nanoparticles provides a step towards fabrication of hybrid photonic devices for applications from quantum cryptography to sensing.

Integration of Diamond-Based Quantum Emitters with Nanophotonic Circuits

“…In order to compare this value to the uncoupled (free) case, we collected the experimental data with excitation powers that allow direct comparison with literature values. Because the lifetime in nanodiamonds can vary, we use the interval of τ 1,free = 22.8 ± 6.2 ns from a large statistical study, which agrees well with reference measurements we performed on our devices as well as other studies that used nanodiamonds of similar specifications and positioning technique , (see Supporting Information for further details). We thus estimate a Purcell factor of , which clearly exceeds the vacuum contribution of F P,vac = 1.…”

“…Quantum optics experiments at the single-photon level suffer significantly from background noise, as for example the autofluorescence encountered when working with well-established silicon nitride-on-insulator nanophotonic devices . Combining novel platform-agnostic lithographic positioning techniques with dielectric material systems that exhibit extremely low levels of autofluorescence and low transmission loss (−1 dB/cm), such as tantalum pentoxide (Ta 2 O 5 ), , promise to overcome these limitations, thus enabling nanophotonic chips that integrate large numbers of quantum emitters in reproducible, high-yield nanofabrication processes with nanometer placement accuracy. ,, Well-established interfaces between such chips and fiber optic arrays then enable the simultaneous manipulation and readout of many independent quantum systems for parallel on-chip quantum processing capabilities …”

Microscale-Resolution Thermal Mapping Using a Flexible Platform of Patterned Quantum Sensors

“…We note that this result implies that this patterning technique can be used to create permanent arrangements of solid state qubits for sensing or quantum information purposes on any sample compatible with the fabrication process. Other approaches were recently used to position nanodiamonds on permanent substrates, 21,22 although the control on the number on nanoparticles per spot was not demonstrated, and near 100 % yield and selectivity cannot be achieved simultaneously. Our fabrication process therefore also provides an important advance in the creation of stable ND arrays for quantum applications.…”

Fluorescence profile of a nitrogen-vacancy center in a nanodiamond

“…A drawback of fluorescent nanodiamonds in comparison to quantum dots and organic molecules is their intrinsic heterogeneity. Large variations in fluorescence intensities and lifetimes are observed between NV centres in similar nanodiamonds [25][26][27][28]. Understanding the origins of such variations and the ways of reducing the heterogeneity is important for developing a reliable technological platform.…”