Transmon qubits are a leading candidate to encode quantum information. Many recent works have shown that the strong voltages used to measure transmon qubits can excite them to more energetic states in an uncontrolled way. In collaboration with the University of Pittsburgh and Yale University, we showed that this effect also limits the speed at which the qubit can be controlled, even when using highly off-resonant low-frequency voltages. Our theory explains observations and provides an avenue for improving quantum control in the near future.

Enjoy the read!

This spring, two new articles involving members of the groupe appear on the arXiv. Below is a brief summary along with the link to access them.

First article : Transmon qubits are a leading candidate to encode quantum information. However, it is known that the strong voltages used to measure these qubits can induce measurement errors by exciting the qubit to a more energetic state. In collaboration with the University of Rochester, we studied these excitations and were able to control them. Our theory explains observations and provides tools to improve measurement in the near future.

Second article : One of the advantages of transmon qubits is their resilience against unavoidable electric noise in their environment. However, it was recently suggested that the measurement of these qubits is not protected against such noise. In collaboration with the Karlsruhe Institute of Technology, we studied the effect of electric noise on transmon measurement. Our theory explains observations and suggests strategies to improve measurement in the near future.

Enjoy the read!

We recently welcomed Rémy Lyscar to the group. Originally from France and currently a first-year Master’s student in Fundamental Physics at the University of Paris-Saclay, he is doing a three-month internship with the group.

Last fall, we welcomed two new members in the group.

Benjamin Levitan completed his graduate studies at McGill University, obtaining his M.Sc. under the direction of Aash Clerk, and his Ph.D. with Tami Pereg-Barnea. After a first postdoc at the Weizmann Institute of Science, he recently joined the group for a second postdoc.

Tianrui completed her M.A. and Ph.D. under the direction of Prof. Joel E. Moore, followed by her first postdoc with Prof. Ana Maria Rey at JILA. She recently joined the group as a postdoc.

Measurement of the transmon in circuit QED does not have the fidelity expected from theory. In a new paper published in PRX, we present a unified picture of this phenomenon which is in agreement with experiments. 

This spring we are welcoming 4 new members in the group!

First, Boris Mihailov Varbanov, originally from Bulgaria, completed his master’s degree at the Delft University of Technology and then joined the QuTech research institute within the same university for his Ph.D. under the direction of Barbara Terhal. He recently joined the group as postdoc.

Baptiste Hoyau, from France, is currently completing his master’s degree in physics at EPFL (Lausanne). He will be an intern in our group from March to August 2024, then he will continue with us as a PhD student next fall.

Philippe Gigon, originally from Switzerland, is currently completing his master’s degree in Quantum Physics at the Ecole Normale Supérieure in Paris. He will be an intern with the group from April to August 2024.

Lev-Arcady Sellem, from France, completed a PhD at L’École des Mines and Inria in Paris, under the supervision of Pierre Rouchon and Claude Le Bris. He recently joined the group as a postdoc, co-directed by Pr Baptiste Royer.

Congratulations to Camille, who defended her thesis last December! Originally from France, she came to Institut Quantique to complete her PhD with the group, in cotutelle with the University of Strasbourg. As part of the QSciTech program she took part in during her PhD, she is currently completing an internship at Nord Quantique, a Sherbrooke-based quantum computing start-up.

This autumn, we welcome two new members!

Alex Chapple is starting his PhD with the group. He has just arrived from New Zealand, where he completed his master’s degree in physics at the University of Auckland.

Simon Richer joins us to start his master’s degree, after completing a bachelor’s degree in engineering physics at Polytechnique Montréal.

Welcome to you both!