• May 2019

Samuel Boutin has obtained his well-deserved doctorate. He will soon depart for California to start a postdoc at Microsoft Station Q. Congratulations and all the best for your career! 

Here is a link to Samuel's thesis (in French):


  • April 2019

The article Influence of Landau levels on the phonon dispersion of Weyl semimetals has been published in Phys. Rev. B. Here is a link to the paper, along with a short summary:

Weyl semimetals display unusual electronic transport properties when placed under magnetic fields. Here, we investigate how magnetic fields alter the dynamics of long-wavelength lattice vibrations in these materials. To that end, we develop a theory for the phonon dispersion, which incorporates contributions from chiral and nonchiral Landau levels, electron-phonon interactions, electron-electron interactions, and disorder. We predict (i) a magnetic-field-induced hybridization between optical phonons and plasmons, (ii) avoided crossings between pseudoscalar optical phonons and electronic excitations originating from nonchiral Landau levels, and (iii) a sharp dependence of the sound velocity on the relative angle between the sound propagation and the magnetic field. We compare our results to recent theoretical studies on the signatures of the chiral anomaly in phonon dynamics.


  • January 2019

The article Microwave signatures of the Z2 and Z4 fractional Josephson effects has been published in Phys. Rev. B.  Here is a link to the paper, along with a short summary:

We present a many-body exact diagonalization study of the Z2 and Z4 Josephson effects in circuit quantum electrodynamics architectures. Numerical simulations are conducted on Kitaev chain Josephson junctions hosting nearest-neighbor Coulomb interactions. The low-energy effective theory of highly transparent Kitaev chain junctions is shown to be identical to that of junctions created at the edge of a quantum spin Hall insulator. By capacitively coupling the interacting junction to a microwave resonator, we predict signatures of the fractional Josephson effects on the cavity frequency and on time-resolved reflectivity measurements.


  • December 2018

Pierre Rinkel has obtained his well-deserved doctorate. Congratulations Pierre and all the best for the future! Here is a photo of Pierre with the members of his thesis committee. 

And here is a link to Pierre's thesis (in French):


  • December 2018

The article Majorana bound state engineering via efficient real-space parameter optimization has been published in Phys. Rev. B. Here is a link to the paper, along with a short summary:

Recent progress toward the fabrication of Majorana-based qubits has sparked the need for systematic approaches to optimize experimentally relevant parameters for the realization of robust Majorana bound states. Here, we introduce an efficient numerical method for the real-space optimization of tunable parameters, such as electrostatic potential profiles and magnetic field textures, in Majorana wires. Combining ideas from quantum control and quantum transport, our algorithm, applicable to any noninteracting tight-binding model, operates on a largely unexplored parameter space and opens new routes for Majorana bound states with enhanced robustness. Contrary to common belief, we find that spatial inhomogeneities of parameters can be a resource for the engineering of Majorana bound states.


  • August 2018

Pedro Lopes is ending his postdoctoral stay at our Institut Quantique. Next, he will be a postdoctoral fellow at the Stuart Blusson Institute of Quantum Matter, at the University of British Columbia. Thank you for all you have done in our group, and best of luck! 

  • August 2018

Jorge Ramírez has obtained his MSc diploma.

Here is the link to his thesis:

Next, he will be going to Spain to embark on a PhD in neuroscience. Felicidades y mucha suerte en el futuro!

  • May 2018

Jean-Michel Parent will be starting his MSc under the guidance of my colleague René Côté and myself. Welcome!

  • March 2018

The article Origin and evolution of surface spin current in topological insulators has been published in Physical Review B. This was a collaboration between our theory group and a group of experimentalists in Chalmers University (Sweden). Here is the link to the article, along with a short summary:

The Dirac surface states of topological insulators offer a unique possibility for creating spin polarized charge currents due to the spin-momentum locking. Here we demonstrate that the control over the bulk and surface contribution is crucial to maximize the charge-to-spin conversion efficiency. We observe an enhancement of the spin signal due to surface-dominated spin polarization while freezing out the bulk conductivity in semiconducting Bi1.5Sb0.5Te1.7Se1.3 below 100K. Detailed measurements up to room temperature exhibit a strong reduction of the magnetoresistance signal between 2 and100K, which we attribute to the thermal excitation of bulk carriers and to the electron-phonon coupling in the surface states. The presence and dominance of this effect up to room temperature is promising for spintronic science and technology.


  • February 2018

Kush Saha, former postdoctoral fellow in our group, has accepted a faculty position in the National Institute of Science and Engineering in Bhubaneswar, India. Kush came to Sherbrooke after doing a PhD at the Indian Institute for the Cultivation of Science, under the guidance of Krishnendu Sengupta. He stayed with us between 2013-2015, conducting research on the topic of electron-phonon interactions in topological insulators. Afterwards, he did further postdoctoral research at the University of California and at the Max Planck Institute. Congratulations Prof. Saha! 


  • December 2017

The article NMR in an electric field: A bulk probe of the hidden spin and orbital polarizations has been published in Physical Review B. It has been chosen as an Editors' Suggestion, i.e. an article that the editors or the referees consider to be of particular interest. Only 5% of the articles published in PRB are chosen as Editors' Suggestion. Thank you Jorge and Samuel for your work! Here is the link to the article, along with a short summary:

The recent discovery of spin and orbital textures in nonmagnetic crystals with inversion symmetry has broadened the scope for spintronics applications. These so-called hidden polarizations are however difficult to probe, in part because they average to zero within each unit cell. In this work, the authors show that a bulk detection of intra-unit cell spin and orbital textures can be achieved with nuclear magnetic resonance by splitting, with an electric current, the resonance peak of inversion partner nuclei. The proposal is illustrated with numerical results for Bi2Se3 and Bi2Te3, and other promising materials are identified on the basis of their crystal symmetries.