During the e-SI-Amp project there have been many opportunities for in-depth training, typically in the operation of electron pumps, or in high accuracy small current measurements (and associated noise debugging).

One particular example, which includes many of these activities, is the training that PhD student Ilaria Finardi (INRiM) received while a guest at PTB, Braunschweig.

We asked her some questions to give an overview of her experience:


Ilaria Finardi presenting her work on single electron device measurements at a conference on electrical measurements in Modena, Italy.

Tell us about yourself and your host institution.

My name is Ilaria Finardi and I’m a Physicist. Actually I’m at the end of my PhD in Metrology which is held by Politecnico di Torino in collaboration with INRiM (Istituto Nazionale di Ricerca Metrologica), the italian National Measurement Institute. My supervisors are Luca Callegaro and Massimo Ortolano.

What is the title of your thesis?

The title of my thesis is not finalised, but it is strongly focused on the measurements of ultralow currents produced by single electron devices. In few words, I can say that I analyzed the performance of the instruments used in the measurement of low currents and how they can be calibrated to be traceable to the SI. At the end I participated to an experiment measuring the current produced by single electron devices and I mainly contributed to the noise analysis of the experiment and how it could be reduced.

You did a secondment at PTB: Who did you work with and what did this involve?

Between 2017 and 2018 I had the opportunity to be hosted in the PTB’s headquarters in Braunschweig for nine months. In particular I was guest researcher in two different departments: I spent the first three months in the department of Electrical Quantum Metrology and the remaining six in the department of Semiconductor Physics and Magnetism.
In the first part of this experience I was involved in the calibration of the first generation Ultrastable Low-noise Current Amplifier (ULCA) by means of a 14-bit Cryogenic Current Comparator. I worked mainly with Martin Götz and Eckart Pesel. In the second part I worked on the fabrication and characterization of a cryogenic probe especially dedicated to perform high accuracy experiments involving single-electron pumps.
During the final part of my stay I also had the chance to participate to one of these experiments that allowed me to test the new probe during the running measurements and estimate the noise contribution introduced by the measuring system to the current produced by the pump.  For this last part I worked in particular with Niels Ubbelohde, Dario Maradan and Thomas Gerster.

What was the most challenging part?

I was really pleased to participate at the activities carried out at PTB. The topics investigated were very close to my research field, so I was very interested in all the aspects involved: from the calibration of the ULCA to the data analysis of the experiment regarding single-electron pumps. I think the most challenging part was finding ways to properly optimize the experimental setup and to reduce the noise that this can introduce to the current measurements. Also the data analysis required a lot of effort.