Hi Adrien, thanks for taking the time with us. How would you present yourself to our scientific community?
My research path reflects my strong curiosity for questions of physics spanning over a broad range, from photonics and material sciences to quantum electromechanics, low-temperature physics and nanofluidics. I would say that what defines me most, scientifically speaking, is my strong eagerness for challenging experimental approaches (measuring tiny signals and objects). To me, this is mostly where the potential lies to lead to scientific breakthrough.
The record for mass sensing has reached yoctogram resolution in a group where you have worked already in Barcelona. What else do you want to bring to this field?
I envision that we can ‘open up the cryostat’: indeed, the exquisite sensitivity reported Adrian Bachtold's group [1] was achieved in cryogenic environment, meaning both low temperature and low pressure. It is now time to extend the use of carbon nanotube resonators to room temperature, and why not even ambient pressure. In the long term, this will unlock sensing applications, in particular for nanofluidics – a field where there is a lot of simulation but little experimental counterparts.
When it comes to measuring nano-objects, such as single quantum dots or nanotubes, improving signal-to-noise is a necessity, often benefiting from resonant effect. What have been your different strategies on this front?
My strategy has been to work on improving both signal and noise, and I can say this strategy has proven successful to address minute signals.
During my PhD thesis, I developed the use of on-chip integrated optical cavities to greatly improve the measured photoluminescence signal of nanotubes, while more efficiently rejecting the non-resonant background. Benefiting from resonant effects here was critical, both for the emission of the nanotubes in the cavity modes, but also for efficient coupling of the laser excitation (doubly resonant scheme).
To give you another example of this strategic choice: when it comes to nanotube mechanical resonators, I have developed a setup to work at a higher frequency than previously used in the community, lowering the noise term (owing to 1/f background in the measurement electronics). It was also important to select the correct amplification chain to improve the signal, with a custom-made low-noise amplifier at the very first (cryogenic) amplification stage. An RLC tank was added just before the low-noise amplifier, both to filter the noise and amplify the signal on top of the RLC resonance. Last but not least, the whole chain works because the Zurich Instruments Lock-in Amplifier has a very low input noise!
By now, you have been using Zurich Instruments for many years, in different contexts and institutions. How do you see new instrumentation development in the field of research?
Having pursued my full career in the field of nanotechnologies, it is clear to me that new progress is always concomitant to the development of the right measurement tools. Speaking of lock-in, I believe Zurich Instruments offers a great combination of high speed (I used the UHFLI, going up to 1.8 GSa/s!) and flexibility thanks to its all-in-one toolkit. For young researchers, the interface is great and more intuitive than standard analog lock-ins. I believe this is the big advantage of all-digital lock-ins.
A daring final question: what is the craziest thing you’ve done (or would have liked to do) in your scientific career? What would you recommend to young researchers nowadays?
My today’s research project! (Laughs). It is both a unique idea and quite a challenging experiment to set up. But this is exactly why I do research, and we are now managing to have everything working, thanks also to the help of Romain Stomp from ZI on the development of a fast PID for nanotube resonators.
My advice for young researchers is to always think one step ahead and not follow the trend. Following the trend means you will never be at the forefront, which is what is expected from you as a researcher. And thinking one step ahead will help you always optimize your research path, especially towards a permanent researcher position, which is more and more difficult nowadays.
[1] Chaste, J., Eichler, A., Moser, J. et al. A nanomechanical mass sensor with yoctogram resolution. Nature Nanotech 7, 301–304 (2012). https://doi.org/10.1038/nnano.2012.42
