Julien Camirand Lemyre

Micromagnets: A giant leap forward for quantum computing

Julien Camirand Lemyre (right) and his research director, Michel Pioro-Ladrière (left), from the Institut quantique. (Photo taken before the distancing measures).

Photo : Michel Caron

Julien Camirand Lemyre, an expert from Sherbrooke on the manipulation of quantum information using micromagnets, and his research director, Michel Pioro-Ladrière, contributed to an inter-university study published in Nature. The study could facilitate the development of future generations of quantum computers.

Exactly 150 years after the invention of the periodic table of elements, micromagnets integrated into artificial atoms open up new horizons in the manipulation of quantum information.

Julien Camirand Lemyre delved into this research theme and carried out his postgraduate studies in physics at the Institut quantique (IQ), under the supervision of Professor Michel Pioro-Ladrière, the inventor of the micromagnet technique. Their ultimate goal is to find the right base unit, the quantum bit or qubit, which will be used to build the quantum computer.

“My research is based on what is called a quantum dot,” explains Julien. “I build chips that behave like artificial atoms, which can trap a single electron. My thesis contribution relates to the use of micromagnets. My job is to find a way to add the micromagnet to quantum dots without corrupting their quantum properties. This is not an easy thing to do.”

Micromagnets allow a more efficient and faster manipulation of the spin that encodes the quantum information. To date, micromagnets are the most efficient technique to manipulate the spin of artificial atoms in quantum computing. The hope is that these micromagnets can be used as a basis for building the quantum computer.

According to Professor Pioro-Ladrière, Julien’s work on micromagnets is the way of the future for the process developed in his laboratory:

“When we think of a physicist, images of a laboratory rat often come to mind. With Julien, it’s the complete opposite. He dares to leave the laboratory, to step outside the university walls to speed up discoveries. Julien’s contribution to the publication in the prestigious journal Nature stems from his entrepreneurial approach to research.”

Publication in Nature

Professor Pioro-Ladrière’s team, including Julien, has been working for some time on a joint university study based on micromagnets. It is a collaboration between UdeS and the Centre for Quantum Computation and Communication Technology at the University of New South Wales (UNSW) in Australia.

By integrating a micromagnet into a purified silicon-based device manufactured by UNSW, the group of researchers has made a breakthrough that could help advance quantum computing. The discovery was recently published in the prestigious scientific journal Nature.

“Most qubit experiments for quantum computing are performed at very low temperatures,” explains Julien. We are talking about ten millikelvins – temperatures that do not exist on Earth or even in space. That’s very cold! People are able to build dilution refrigerators to reach such temperatures. In the article, the architecture based on micromagnets makes it possible to overcome this [low temperature] constraint and operate the quantum bits at a higher temperature. We work at 1 Kelvin – that’s the new thing. At this temperature, we plan to be able to integrate the necessary control electronics for qubits. For the quantum computer, this represents a step forward.”

Institut quantique’s contribution to this publication is significant. In addition to providing the technique for placing the micromagnets in quantum dots, IQ researchers designed the magnet to suit the device. UNSW researchers carried out the fabrication of the devices and the experimental demonstration. “The expertise of our colleagues at UNSW is in the operation of spin qubits and in nanofabrication of silicon devices,” adds Julien. “In Sherbrooke, we are used to integrate micromagnets into various types of architectures. We therefore pooled our knowledge to enable the fabrication and implementation”.

While this is an important step forward, Julien does not intend to sit back and take it easy. “We haven’t achieved the performance we’d like to have. There is still work to be done at this level. We have demonstrated how to operate at higher temperatures and now we need to improve things. We have taken a step, and we will continue to build on that step.”

We can expect to see more collaborations between the IQ and other quantum science laboratories in the near future. Nevertheless, pooling complementary expertise is one of the strengths of UdeS and Julien.

A committed and interdisciplinary student

One need only look at the various promotional tools related to the IQ to understand that Julien is a prominent student at UdeS. From his bachelor’s to the doctoral level, he has always been deeply committed to advancing science by breaking down barriers between disciplines: “One thing I have always done as part of my master’s and PhD thesis is work with a lot of people, especially engineers. At the IQ, there was a desire to build bridges between people from different branches. In 2015, I started the IQ student committee to fill the gaps between different student factions.”

In addition to his doctoral studies, Julien also carries out extra research work. Among other achievements, he started two micromagnet related projects with another student, funded by the IQ. “This Institut quantique’s approach has allowed us to grow beyond our respective doctoral projects,” says Julien. The IQ student committee also encourages the realization of larger projects by bringing together people and disciplines: engineering, quantum physics and quantum materials.”

With a doctorate in his pocket, this piano and badminton enthusiast does not intend to stop there: “I will continue to develop quantum processors,” he says, adding that an entrepreneurial project is currently under development. It’s safe to assume that the young physicist is destined for a bright future.

About the publication in Nature

The Operation of a silicon quantum processor unit cell above one kelvin study is the fruit of a collaboration between the UdeS and the University of New South Wales (Australia). The experiments and writing of the article were carried out at the University of New South Wales by two students, Chih-Hwan Henry Yang and Ross Leon, under the supervision of Professor Andrew S. Dzurak. For its part, the UdeS contributed its expertise in micromagnets through the work of Julien and Professor Michel Pioro-Ladrière.



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