Quantum & Computational Physics

theory lab of Stefanos Kourtis

Université de Sherbrooke

Université de Sherbrooke

We are a theoretical and computational physics lab in the Department of Physics and Institut Quantique of Université de Sherbrooke. Our research lies at the crossroads of quantum matter and computational physics. We build and study models of quantum systems to uncover and understand exciting phenomena. We also develop numerical methods to solve problems in physics and across disciplines, particularly in relation to quantum information and artificial intelligence.

**NOW HIRING:** There are openings in the lab for interns, MSc and PhD students, and postdocs; if you are interested, get in touch.

Correlations & Topology in Quantum Matter

Overview

Quantum states of matter are sources of striking physical phenomena and a launchpad for technological innovation. In **topological materials**, for example, electrons acquire properties that can be described in terms of the mathematical field of topology. These topological properties are observed in experiments and can potentially power better electronics. Unconventional quantum states often arise in **correlated quantum systems**, in which competing inter-particle interactions give rise to collective behavior that is fundamentally different from that of a collection of independent degrees of freedom.

Our work

We study topological and correlated quantum states of matter in order to elucidate their fundamental properties. Systems of interest include quantum spin liquids, fractional quantum Hall models, and topological semimetals. We also work on predicting and explaining experimental observations in these systems.

Selected publications

Modelling & Simulation of Quantum Systems

Overview

The simulation of quantum systems is a basic step in the development of quantum technologies. Modelling **quantum dynamics**, in particular, is essential in certifying and benchmarking **quantum computation**. Significant efforts are also invested in understanding and controlling the dynamics of quasiparticles in quantum matter. This is intricately related to desired quantum material and device properties and can unlock new functionalities in the laboratory.

Our work

We build models that capture important aspects of quantum many-body physics and develop theory and numerical methods to solve them. We focus on effects that arise due to quantum entanglement, particularly as it relates to quantum computation and its simulation on classical computers. We also model dynamics in correlated quantum systems, such as systems with fractional quasiparticle excitations or with many-body constraints in their kinetics. This allows us to interpret or predict their responses in experiments, such as inelastic scattering, at zero and finite temperatures.

Selected publications

Physics-Inspired Methods Across Disciplines

Overview

Intuition from theoretical physics often fuels progress in other fields. **Quantum information**, for example, was born out of the vision of employing principles of quantum mechanics to overcome the limitations of ordinary computers. Another important ongoing synergy exists between statistical physics and computational problems that arise in **artificial intelligence**. Research in these directions has created a growing interdisciplinary space between physics and computer science, with the ultimate goal of addressing real-world problems.

Our work

We employ our expertise in theory, models and methods for quantum many-body systems to solve problems across disciplines. We work on computational challenges related to artificial intelligence, such as combinatorial optimization and model counting. We are also interested in modelling and simulating quantum circuits, algorithms, and error correction. We leverage quantum mechanical reasoning and physical principles to tackle the above problems as efficiently as possible, even on classical computers.

Selected publications

Research

People