26 January 2020 Jessica Blakeney
He Joins the Institut Quantique Team

Dany Lachance-Quirion’s Research Published in Science

Dany Lachance-Quirion

Photo : Photo : UdeS - Karine Couillard

During a postdoctoral internship at the University of Tokyo, Dany Lachance-Quirion joined professor Yasunobu Nakamura’s research group. The group successfully demonstrated single-shot detection of single magnons via entanglement of a quantum bit (qubit) with a magnetically-ordered system. The scale of this discovery led to a publication in Science: “Entanglement-based single-shot detection of single magnons with a superconducting qubit”.

Quantum magnonics

The team demonstrated the first single-shot detection of single magnons, quanta of collective spin excitations in a magnetically-ordered system, by using a superconducting qubit as a quantum sensor.

To achieve a single-magnon detector with a high quantum efficiency, it is necessary to combine, in a single experiment, high-fidelity time-resolved control and readout of the superconducting qubit magnetostatic mode of a ferromagnetic crystal.

“The discovery of the detection of single magnons happened unexpectedly when I was measuring a certain signal. I was reducing the averaging of the system, until I no longer averaged at all, and the signal was still present”, explains Dany. It was by improving the experiment and by tweaking the simulations over a six-month period that Dany achieved a quantum efficiency of 71% for the single-shot detection of single magnons.

The demonstration of a high-fidelity single-shot detection of a single magnon based on entaglement establishes a new connection between quantum sensing with magnetism and represents a significant advance for a broad range of communities in quantum technology, quantum sensing, hybrid quantum systems, magnonics and spintronics.

Towards quantum technologies: from spintronics to dark matter

Quantum magnonics offers a platform for new developments in fundamental physics: “everything we have developed to detect a single-magnon, from the level of control to the qubit detection efficiency, will allow us to go toward new directions.”

An interesting application concerns spintronics. Indeed, one of its sub-branches is magnonics based on spintronics, which is essentially a spin wave which propagates in a system, thus allowing classical calculations. “The limit of the sensitivity of the conversion of a magnon to an electric signal for magnonic-based spintronics is therefore a first application.” In other words, the excitation of a single magnon is the equivalent of oscillating the magnetization vector in the ferromagnetic material used in the experiment by about 10-17 degrees. Despite this incredibly small amount, the single magnon still provides a macroscopic electrical signal.

From a quantum technological point of view, quantum magnonics is a demonstration of hybrid quantum systems, i.e. a combination of different quantum systems in which only the advantageous properties of each system are preserved. “We managed to combine very different systems, including superconducting qubits, which cannot be placed in a magnetic field, with a ferromagnet, which requires an incredible magnetic field.” This combination allows optimal performance for each of the components. This is a milestone for quantum technologies when it comes to quantum hybrid systems.

Finally, from a fundamental physics point of view, electronic spins can potentially interact with axions, dark matter candidates. “Imagine that the Earth is moving across the galaxy and through dark matter, which is everywhere. This can potentially produce an effective magnetic field, which could excite the quanta of spin excitations, the magnons. In other words, by continuously measuring with the single magnon detector, we can potentially determine if dark matter interacts with electronic spins.”

Dany’s expertise at the service of Institut Quantique

The Institut quantique (IQ) will now be able to benefit from Dany’s knowledge and expertise. In fact, he will pursue his research career within the IQ team as a research professional under the supervision of Prof. Eva Dupont-Ferrier and Prof. Michel Pirio-Lardière. “I am delighted that Dany is joining IQ, my research team and that of Prof. Pioro-Ladrière. Dany’s expertise, motivation and vast knowledge of quantum systems will help energize and accelerate our research programs and the IQ’s outreach” explains Prof. Dupont-Ferrier.

In his new role, he will make sure their labs work optimally and will supervise students. “In Tokyo, I supervised students and made sure their experiments were going well, so I’m very comfortable with this role.”

Indeed, Dany is certain that his technical knowledge will serve him well in his new role at the QI, and is happy to be able to use his expertise in quantum technologies within the research professional position.

In addition to his experience in Tokyo, Dany had complementary experiences during his doctorate degree at the Université de Sherbrooke: “at the end of my doctorate degree, the QI launched calls for projects. Students were asked to think of projects that went beyond the scope of their professors’ research program, and to build a team and a budget. It was an incredible experience that will undoubtedly serve me well in my new role.”

The IQ’s dynamic and innovative environment motivated Dany to join the team. Passionate about science, he hopes to become an integral part of the IQ in order to contribute to its development and sustainability. “I’m ready to get involved. I have the motivation and I believe I have the scientific knowledge to contribute to the prosperity of the IQ.”

Dany adds that anyone who wants to be successful with a publication must first believe in the value of its results. All in all, seeing his latest work published in Science is a great source of motivation to start his career at the IQ.


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