As part of the IQ call for projects

Michael Lacerte designs an interposer that could replace microwelding

Photo : UdeS Karine Couillard

The call for projects’ objective is to provide members with the necessary resources to achieve the IQ’s ambitious research objectives. As part of the 2017 edition, physics technician Michael Lacerte submitted a project to design a part called an “interposer”, which serves to avoid the use of microsoldering.

In quantum technologies, microsoldering is essential to bind samples to sample holders in order to connect the latter to measuring instruments and collect data. However, this technique is time consuming and carries a high risk of damaging the samples, which are both fragile and valuable. Hence the idea of ​​working on an interposer that would replace microwelding, while preserving connection reliability and the data’s integrity.

Encouraged in his efforts by Prof. Pioro-Ladrière, Michael started his project. After having documented and informed himself, he tested several interposer models, the principle of which is as follows: it includes the sample and the sample holder, and small springs establish contact between the two parts. Mr. Lacerte is confident that his latest model will meet expectations. In addition to reducing the risk of sample breakage, the goal is for the interposer to save scientists valuable time, who sometimes have to spend entire days microwelding. This will also facilitate electrical grounding, in addition to being able to be reused several times, which increases its practicality.

However, “several issues threaten the integrity of said interposers in a quantum measurement environment, especially with regard to their performance at cryogenic temperatures (eg colder than -272 °C),” says Professor David Danovitch. However, preliminary tests in collaboration with Prof. Michel Pioro-Ladrière and Prof. Danovitch’s electrical engineering group have shown very encouraging results.

The work resulting from this collaboration would represent a major breakthrough, as very few people in the world have worked with an interposer for a quantum application. This is therefore a first for the Université de Sherbrooke. But Michael doesn’t want to keep this breakthrough to himself, on the contrary: “I think scientists in other labs should be more aware of this project because I think it could be of use to a lot of people. If we can remove as much microwelding as possible, that can be really great.” Thanks to his work on this project, Michael was able to apply for the Level 1 Physics Technician degree, which denotes significant involvement in his field.

For Prof. Pioro-Ladrière, this project reflects the IQ’s DNA: “The Institut quantique places the student community as well as the professional and technical team at the center of research. By leading his own research project, by daring to transform, Michael demonstrates all the power of this new way of doing research. By creating his interposer from scratch, like an inventor, Michael is accelerating the development of quantum technologies here at the Université de Sherbrooke!”

Michael subscribes to the IQ’s vision of openness that Professor Pioro-Ladrière talks about. He even mentions that he had carte blanche for his project: “I found things, I submitted them, and then everyone agreed.”

The next step? “Now that I know I can use it at cryogenic temperatures, I still have to test the interposer with real samples to make sure everything works as expected,” explains Michael.

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