Working together to improve light yield – The Nano Argovia project NQsense seeks to optimize the sensitivity of quantum sensors for nanoscale applications

Dr. Felipe Favaro De Oliveira, CTO at Qnami, seeks to optimize the sensitivity of quantum sensors.

In the NQsense project, the team working under project leader Professor Patrick Maletinsky plans to fabricate a fully integrated quantum sensor with significantly improved sensitivity. This sensor could be used, for example, to support basic scientific research in the areas of materials science or to perform failure analyses in the semiconductor industry.

Diamonds as sensors
The team of scientists from the Department of Physics at the University of Basel, the Paul Scherrer Institute, and the industrial partner Qnami – a start-up from the Department of Physics at the University of Basel – is basing its work on tiny quantum sensors made of diamonds.

These are created by deliberately removing two carbon atoms from the diamonds’ crystal lattice. One is replaced with a nitrogen atom, and the second is left as a vacant site in the lattice. These nitrogen-vacancy centers (NV centers) host individual electrons that can be excited and manipulated. The intrinsic angular momentum (spin) of these electrons, and their electric dipole, are extremely sensitive to tiny magnetic and electric fields. Exposing the diamond sensor to fields of this kind causes a change in the intensity of the NV center’s luminescence. This can be detected using an optical device and used to draw specific conclusions about the influencing field.

Ambitious goals
In recent years, the team has already achieved significant improvements in the tiny sensors’ complex and demanding production process. Now, the scientists are exploring ways to boost the sensitivity of their sensors. That is easier said than done, because diamonds have a high refractive index. As a result, most of the light emitted by the NV centers is reflected inwards by the outer surfaces, leaving it unavailable for measurements.

“At the moment, we can use about one to two percent of the emitted photons for our measurements. As part of the Nano Argovia project NQsense, we now want to design and produce structures that allow us to boost the yield to up to 50 percent,” comments Professor Patrick Maletinsky on the impending challenge.

“The Nano Argovia program offers the ideal framework for our product’s further development, as we can exploit synergies with our partners at the University of Basel and the Paul Scherrer Institute, as well as benefiting from our partners’ excellent technical equipment,” says Mathieu Munsch, CEO of the industrial partner, Qnami.