November 18, 2025 10:55 AM
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November 19, 2025 4:30 PM
November 18, 2025 10:55 AM
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November 19, 2025 4:30 PM
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Hôtel Château Bromont
Hôtel Château Bromont
Opening Remarks
Pr Mathieu Juan, Institut quantique - Université de Sherbrooke
Clasical and quantum computations as tensor networks
Pr Stefanos Kourtis, Institut quantique - Université de Sherbrooke
Classical and quantum computations as tensor networks
Break
Event organized in collaboration with the RQMP and animated by Mrs. Chloé Freslon, founder of URelles
Falisha Karpati, Ph.D.
Think Differently Together: Strengthening research and innovation by embracing cognitive diversity
Louis-Philippe Lamoureux (Slides / Présentation)
Thierry Debuischert, Thales - France (postponed to Monday at 13:15 / reporté à lundi 13h15)
Closing remarks of the day
Opening remark of the day
Thierry Debuischert, Thales - France
Professor Tami Pereg-Barnea, McGill University
Dynamic topology - quantized conductance and Majoranas on wires
Professor Philippe St-Jean, Université de Montréal
Topological physics with light and matter: new horizons
Break
Louis Gaudreau, National Research Council Canada (Ottawa)
Entanglement distribution via coherent photon-to-spin conversion in semiconductor quantum dot circuits
Philippe Lamontagne, National Research Council Canada (Montréal)
Black-Box Impossibility in the Common Reference Quantum State Model
Olivier Gagnon-Gordillo, Québec quantique lead
Presentation of the Québec Quantum ecosystem
Institut quantique - Université de Sherbrooke
Classical and quantum computations as tensor networks
Tensor networks are multilinear-algebra data structures that are finding application in diverse fields of science, from quantum many-body physics to artificial intelligence. I will introduce tensor networks and illustrate how they can be used to represent classical and quantum computations. I will then motivate tensor network algorithms that perform or simulate computations in practice and demonstrate their performance on benchmarks of current interest, such as model counting and quantum circuit simulation. I will close with an outline of ongoing work and an outlook on future directions.
Institut quantique - Université de Sherbrooke
Optomechanics with a non-linear cavity
The possibility to operate massive mechanical oscillators close to or in the quantum regime has become central in fundamental sciences. LIGO is a prime example where quantum states of light are now used to further improve the sensitivity. Concretely, optomechanics relies on the use of photons to control the mechanical motion of a resonator, providing a path toward quantum states of massive objects and for the development of quantum sensors. In order to improve this control many approaches have been explored, some more complicated than others. In particular, in order to cool the mechanical motion a cavity can be used to realise side-band cooling. In general, linear cavities are favoured to allow for large photon number providing stronger cooling. I will show that, surprisingly, non-linear cavities can be used to achieve very efficient cooling at low powers. Indeed, even in the bad cavity limit, we have been able to cool a mechanical resonator from 4000 thermal phonons down 11 phonons. Currently limited by flux noise, this approach opens promising opportunities to achieve quantum control of massive resonators, an avenue to study foundational questions.
McGill University
Dynamic topology - quantized conductance and Majoranas on wires
This talk will address the issue of out-of-equilibrium topological systems. While many materials and devices produced in labs today are topological at equilibrium, it is desirable to have a knob to tune or induce topological properties. For example, if we could dynamically turn a superconductor into a topological superconductor we may create the sought after Majorana fermions which are potential building blocks of quantum bits.
In this context we will explore the possibility of perturbing quantum systems using time-periodic fields (i.e., radiation) and use the Floquet theory to characterize the driven states. We find that in topological systems, beyond the expected splitting of the spectrum into side bands, a change in the topology may occur. In the case of a topological superconductor, the driven system may develop new Majorana modes which do not exist at equilibrium and can be exchanged on a single wire. A protocol for exchanging Majoranas will be presented.
Université de Montréal
Topological physics with light and matter: new horizons
Topology is a branch of mathematics interested in geometric properties that are invariant under continuous deformation, e.g. the number of holes in an object. In the early 1980s it was demonstrated that similar topological properties can be defined for solids presenting appropriate symmetry elements. The discovery of these topological phases of matter has profoundly impacted our understanding of condensed matter, its influence ranging from better explaining the universality of the conductivity plateaus in the quantum Hall effect to developing new platforms for fault-tolerant quantum computation[i]. In the late 2000s, Duncan Haldane (co-laureate of the Nobel Prize in physics for the discovery of topological phases of matter) demonstrated that this topological physics is not restricted to condensed matter but can also emerge in artificial systems like photonic crystals through a careful engineering of their symmetry properties[ii]. Since then, these photonics platforms have proven to be an amazing resource for pushing the exploration of topological matter beyond what is physically reachable in the solid-state, leading to the emergence of a blooming field called topological photonics[iii].
In this presentation, I will describe recent experimental works based on exciton-polaritons, a hybrid light-matter quasiparticle, which have opened new horizons in topological photonics[iv]. The main advantages of polaritonic systems arise from their dual nature: their photonic part allows for tailoring well-defined topological properties in lattices of coupled microcavities and makes them inherently non-hermitian; on the other hand, their matter part gives rise to a strong Kerr-like nonlinearity and to lasing[v]. I will then discuss in more details a recent work in which we took profit of these assets to experimentally extract topological invariants - a fundamental quantity in topology - in a polaritonic analog of graphene[vi]. Importantly, this has allowed us to directly probe the topological phase transition occurring in a critically strained lattice - i.e. where Dirac cones have merged - a condition impossible to reach in the solid-state. I will conclude this presentation by discussing how topological protection can provide a powerful asset for generating and stabilizing many-body quantum states of light and matter. Such mesoscopic quantum objects are highly desirable as they would provide an extended playground for quantum simulation, sensing applications or for generating exotic states of light such as many-body entangled states[vii].
[i] M. Z. Hasan and C. L. Kane. Rev. Mod. Phys. 82, 3045 (2010)
[ii] F. D. M. Haldane and S. Raghu. Phys. Rev. Lett. 100, 013904 (2008)
[iii] T. Ozawa et al. Rev. Mod. Phys. 91, 015006 (2019)
[iv] D. D. Solnyshkov, G. Malpuech, P. St-Jean et al. Opt. Mat. Express 11, 1119 (2021)
[v] I. Carusotto and C. Ciuti. Rev. Mod. Phys. 85, 299 (2013)
[vi] P. St-Jean et al. Phys. Rev. Lett. 126, 127403 (2021)
[vii] P. Lodahl et al. Nature 541, 473 (2017)
Think Differently Together: Strengthening research and innovation by embracing cognitive diversity
This talk will cover:
Biography
Falisha Karpati, PhD is a neuroscientist turned inclusion consultant. Falisha’s work focuses on using neuroscience to build inclusive environments in academic, research, and scientific organizations. Her approach to inclusion centres on the interconnectedness of cognitive, demographic, and experiential diversity. Prior to starting her consultancy practice, she worked as the Training and Equity Advisor for Healthy Brains, Healthy Lives at McGill University.
Head of Applied Quantum Physics
Thales Research & Technology
Researcher
National Research Council Canada (Ottawa)
In this talk, I will present our proposed long distance entanglement distribution scheme that aims to overcome fundamental limitations present in current optical schemes. By using direct band gap semiconductor quantum dots, efficiency and heralding advantages can be exploited through photon-to-spin conversion. For this reason, materials such as GaAs are superior to Si in this type of applications. I will review current schemes to transfer polarization or time-bin encoded photonic qubits to electron spin qubits and will describe adaptations to employ heavy holes which have a number of attractive properties including g-factor tunability. Finally, I will show preliminary results on quantum dot devices using Van der Waals heterostructures which present several potential advantages such as higher confinement energies due to their atomically thin geometry, easier combination with different substrates and the possibility of encoding information in their valley degree of freedom.
Biography
Louis Gaudreau studied physics at Sherbrooke University, followed by a masters and PhD in co-supervision with Andrew Sachrajda at NRC and Alexandre Blais at Sherbrooke. During his graduate studies, Louis studied electrostatic quantum dots and realized for the first time a coupled triple quantum dot system leading to the investigation of the first exchange-only qubit. During this period he was invited to perform quantum dot experiments in Stefans Ludwig’s group at LMU in Munich. After his PhD, Louis changed fields and studied light-matter interactions by combining quantum emitters and graphene to create different hybrid systems. These experiments were done during his postdoc at ICFO in Barcelona in the nano-opto-electronics group with Frank Koppens where he was awarded the prestigious Marie-Curie fellowship. Finally, since 2015, Louis has worked as research officer at the NRC where he investigates different technologies linked to quantum information.
Researcher
National Research Council Canada (Montréal)
Black-Box Impossibility in the Common Reference Quantum State Model
We explore the cryptographic power endowed by arbitrary shared physical resources. We introduce the Common Reference Quantum State (CRQS) model, where the parties involved share a fresh entangled state at the outset of each protocol execution. This model is a natural generalization of the well-known Common Reference String (CRS) model but appears to be more powerful. In the two-party setting, a CRQS can sometimes exhibit properties associated with a Random Oracle queried once. We formalize this notion as a Weak One-Time Random Oracle (W1TRO), where we only ask of the output to have some randomness when conditioned on the input is still beyond the reach of the CRQS model. We prove that the security of W1TRO cannot be black-box reduced to any assumption that can be framed as a cryptographic game. Our impossibility result employs the simulation paradigm formalized by Wichs (ITCS ’13) and has implications for other cryptographic tasks.
- There is no universal implementation of the Fiat-Shamir transform whose security can be black-box reduced to a cryptographic game assumption. This extends the impossibility result of Bitansky et al. (TCC ’13) to the CRQS model.
- We impose severe limitations on constructions of quantum lightning (Zhandry, Eurocrypt ’19). If a scheme allows n lightning states’ serial numbers (of length m such that n > m) to be combined in such a way that the outcome has entropy, then it implies W1TRO, and thus cannot be black-box reduced to a cryptographic game assumption.
Senior Product Manager
Aspen Technology
Biography
Montreal-based quantum physicist, senior product manager, and full stack developer with strong experience building award-winning hardware and software products. Currently Senior Product Manager at Aspen Technology leading connectivity and AI inference at the Edge. Prior to Aspen Technology, I worked at Machine-To-Machine Intelligence (M2Mi) a leader in IoT Security and Management located at NASA Ames research center in the heart of Silicon Valley.
Prior to M2Mi, built SQR Technologies a belgian quantum based, hardware security startup that pioneered distributed quantum key generation. Acquired by IDQ (Switzerland). Awarded a Ph.D. in Physics (Quantum Cryptography) from the University of Brussels. Research interests include: quantum cloning, experimental quantum cryptography, quantum noise reduction, and quantum random number generation.
10h55 Mot d'ouverture (Salon A)
11h00 Présentation (Salon A)
12h00 Diner (Salle Knowlton)
13h30 Présentation (Salon A)
14h30 Présentation (Salon A)
15h00 Pause café (Salon C)
15h30 Présentation (Salon A)
16h00 Présentation (Salon A)
16h30 Session : Écosystème quantique (Salon A)
17h00 Session d'affiche avec rafraîchissement (Salon C)
19h30 Souper INTRIQ (Salle Knowlton)
9h00 Présentation (Salon A)
10h00 Présentation (Salon A)
10h30 Pause café (Salon C)
11h00 Présentation (Salon A)
12h00 Diner (Salle Knowlton)
13h30 Présentation (Salon A)
14h30 Présentation (Salon A)
15h00 Pause café (Salon C)
15h30 Présentation (Salon A)
16h00 Présentation (Salon A)
16h25 Mot de fermeture (Salon A)
Professeur, Université de Sherbrooke
Quantum Error Correction with High-dimensional Systems
Professeure, Université de Sherbrooke
Titre à venir
Professeur, Toronto University
Titre à venir
Doctorant, Université de Sherbrooke
Directrice: Eva Dupont-Ferrier
Spin qubit Singlet-Triplet readout on a CMOS device made from a 300mm integrated process
Étudiant à la maîtrise, Université McGill
Directeur: Kai Wang
Optimization of Gaussian States for Twin-Field QKD
We investigate the use of squeezed displaced states in a twin-field-like quantum key distribution scheme. The interplay between squeezing and displacement in the squeezed displaced states allows for optimizing errors in two complementary bases, in contrast to one basis in the case of coherent states. We find that under special circumstances, the squeezed coherent states surpass coherent states and the superposition of vacuum and single-photon.
The states can be prepared unconditionally and are robust to losses that may open a way for more efficient and long-distance quantum key distribution schemes.
Doctorant, Université de Sherbrooke
Directeur: Max Hofheinz
Titre à venir
Doctorant, Université de Sherbrooke
Directrice: Eva Dupont-Ferrier
Titre à venir
Doctorant, Université McGill
Directrice: Tami Pereg-Barnea
Lyapunov exponents in disordered non-Hermitian models
The topological origin of skin states in translation-invariant non-Hermitian systems has been established for a few years. Yet, a rigorous extension to disordered systems has remained elusive. In this work, we develop a comprehensive topological framework using the Lyapunov exponent for fully general Hatano-Nelson chains with disordered complex-valued potentials and nearest-neighbor hopping. Our approach unifies the theory of non-Hermitian Anderson localization with topologically protected directional amplification, thereby extending the bulk-boundary correspondence to a broad class of one-dimensional non-Hermitian systems. Our work opens new directions for disorder-resilient transport in photonic, optomechanical and superconducting platforms.
Doctorant, Université de Sherbrooke
Directeur: Bertrand Reulet
Titre à venir
Doctorant, Université McGill
Directeur: Hong Guo
Alloy Disorder and Partial Order Effects on the Bowing Parameter and Resistivity of CdZnTe Semiconductors
Cd1–xZnxTe (CZT) is an important semiconductor for applications in radiation detectors. As different concentrations of Zn, x, is alloyed into the CdTe crystal, the band gap of CZT varies with x which can be described by a bowing parameter b that is independent of x. For CZT alloys, however, the measured b appears to have a full range of values, from very small to near unity, across CZT samples fabricated by different methods, experimental conditions, and labs. Such a large variation most likely reflects the microscopic details of the CZT atomic structures. In this work, we theoretically investigated atomic arrangements in the CZT on the bowing parameter by first principles modeling and found that the large variation in the bowing parameter may arise from uneven atomic distributions in partially ordered configurations. Such configurations represent intermediate states between fully disordered and fully ordered alloy structures. In particular, the completely randomized Zn distribution gives rise to small bowing parameters, and the partially ordered structures tend to produce much higher bowing. By comparing ZnTe/CdTe interface models with completely disordered models, this work provides valuable insights into the relationship between atomic arrangements, atomic-scale inhomogeneity, and the electronic properties of CZT. Finally, the disorder-limited resistivities of the CZT alloy models are calculated and compared.
Doctorant, Université McGill
Directeur: Bill Coish
Multiparameter estimation for spin qubits with information amplification
Efficient Hamiltonian parameter estimation protocols are needed to calibrate spin qubits in semiconductor quantum dot devices. For example, two parameters (the strength of the exchange interaction and an Overhauser field gradient) must be estimated before performing a two-qubit gate for Loss-DiVincenzo (spin-½) qubits to achieve good performance. For hole-spin qubits, determining g-tensor elements is another relevant multiparameter estimation problem. We construct and analyze a protocol for information amplification that is applicable to general multiparameter estimation problems. Non-amplified strategies involve successive preparations, free evolutions, and measurements to estimate, e.g., the exchange and Overhauser gradient. In contrast, we consider a protocol involving a sequence of interlaced unitaries that amplifies information about the parameters to be estimated, in direct analogy with noise spectroscopy, where specific Fourier components of the noise spectral density can be amplified through a sequence of pi-pulses. A comparison between the entropy (parameter uncertainty) achieved through amplified and non-amplified protocols is given in Fig. 1. Entropy is favored over the variance as a measure of uncertainty when the associated probability distributions are multi-modal.
Doctorant, Université McGill
Directrice: Tami Pereg-Barnea
Learning shadows to predict quantum ground state correlations
We introduce a variational scheme inspired by classical shadow tomography to compute ground state correlations of quantum spin Hamiltonians. Shadow tomography allows for efficient reconstruction of expectation values of arbitrary observables from a bag of repeated, randomized measurements, called snapshots, on copies of the state. The prescription allows one to infer expectation values of local observables using a number snapshots that scales polynomially with system size when measurements are performed in locally random bases. Turning this around, a bag of snapshots can be considered an efficient representation of the state , particularly for estimating low-weight observables, such as terms in a local Hamiltonian needed to estimate the energy. Inspired by this, we consider a variational scheme wherein a bag of parametrized snapshots is used to represent the putative ground state of a desired local spin Hamiltonian and optimized to lower the energy with respect to it. Additional constraints in the form of positivity of reduced density matrices, motivated by work in quantum chemistry, are employed to ensure compatibility of the predicted correlations with the underlying Hilbert space. Unlike reduced density matrix approaches, learning the underlying distribution of measurement outcomes allows one to further correlations beyond those in the constrained density matrix. We show, with numerical results, that the proposed variational method can be parallelized, is efficiently simulable, and yields a more complete description of the ground state.
Doctorant, Polytechnique Montréal
Directeur: Sébastien Francoeur
Titre à venir
Doctorant, Université de Sherbrooke
Directeur: Mathieu Juan
Vector magnet control for on-chip magnonics
10:55 Opening remarks (Salon A)
11:00 Talk (Salon A)
12:00 Lunch (Knowlton room)
13:30 Talk (Salon A)
14:30 Talk (Salon A)
15:00 Coffee break (Salon C)
15:30 Talk (Salon A)
16:00 Talk (Salon A)
16:30 Quantum Ecosystem session (Salon A)
17:00 Poster session with refreshments (Salon C)
19:30 INTRIQ dinner (Knowlton room)
9:00 Talk (Salon A)
10:00 Talk (Salon A)
10:30 Coffee break (Salon C)
11:00 Talk (Salon A)
12:00 Lunch (Knowlton room)
13:30 Talk (Salon A)
14:30 Talk (Salon A)
15:00 Coffee break (Salon C)
15:30 Talk (Salon A)
16:00 Talk (Salon A)
16:25 Closing remarks (Salon A)
Professor, Université de Sherbrooke
Quantum Error Correction with High-dimensional Systems
Professor, Université de Sherbrooke
Title to be annouced
Professor, Toronto University
Title to be announced
Speakers to be announced
PhD student, Université de Sherbrooke
Director: Eva Dupont-Ferrier
Spin qubit Singlet-Triplet readout on a CMOS device made from a 300mm integrated process
Master student, McGill University
Director: Kai Wang
Optimization of Gaussian States for Twin-Field QKD
We investigate the use of squeezed displaced states in a twin-field-like quantum key distribution scheme. The interplay between squeezing and displacement in the squeezed displaced states allows for optimizing errors in two complementary bases, in contrast to one basis in the case of coherent states. We find that under special circumstances, the squeezed coherent states surpass coherent states and the superposition of vacuum and single-photon.
The states can be prepared unconditionally and are robust to losses that may open a way for more efficient and long-distance quantum key distribution schemes.
PhD student, Université de Sherbrooke
Director: Max Hofheinz
Title to be announced
PhD student, Université de Sherbrooke
Director: Eva Dupont-Ferrier
Title to be announced
PhD student, McGill University
Director: Tami Pereg-Barnea
Lyapunov exponents in disordered non-Hermitian models
The topological origin of skin states in translation-invariant non-Hermitian systems has been established for a few years. Yet, a rigorous extension to disordered systems has remained elusive. In this work, we develop a comprehensive topological framework using the Lyapunov exponent for fully general Hatano-Nelson chains with disordered complex-valued potentials and nearest-neighbor hopping. Our approach unifies the theory of non-Hermitian Anderson localization with topologically protected directional amplification, thereby extending the bulk-boundary correspondence to a broad class of one-dimensional non-Hermitian systems. Our work opens new directions for disorder-resilient transport in photonic, optomechanical and superconducting platforms.
PhD student, Université de Sherbrooke
Director: Bertrand Reulet
Title to be announced
PhD student, McGill University
Director: Hong Guo
Alloy Disorder and Partial Order Effects on the Bowing Parameter and Resistivity of CdZnTe Semiconductors
Cd1–xZnxTe (CZT) is an important semiconductor for applications in radiation detectors. As different concentrations of Zn, x, is alloyed into the CdTe crystal, the band gap of CZT varies with x which can be described by a bowing parameter b that is independent of x. For CZT alloys, however, the measured b appears to have a full range of values, from very small to near unity, across CZT samples fabricated by different methods, experimental conditions, and labs. Such a large variation most likely reflects the microscopic details of the CZT atomic structures. In this work, we theoretically investigated atomic arrangements in the CZT on the bowing parameter by first principles modeling and found that the large variation in the bowing parameter may arise from uneven atomic distributions in partially ordered configurations. Such configurations represent intermediate states between fully disordered and fully ordered alloy structures. In particular, the completely randomized Zn distribution gives rise to small bowing parameters, and the partially ordered structures tend to produce much higher bowing. By comparing ZnTe/CdTe interface models with completely disordered models, this work provides valuable insights into the relationship between atomic arrangements, atomic-scale inhomogeneity, and the electronic properties of CZT. Finally, the disorder-limited resistivities of the CZT alloy models are calculated and compared.
PhD Student, McGill University
Director: Bill Coish
Multiparameter estimation for spin qubits with information amplification
Efficient Hamiltonian parameter estimation protocols are needed to calibrate spin qubits in semiconductor quantum dot devices. For example, two parameters (the strength of the exchange interaction and an Overhauser field gradient) must be estimated before performing a two-qubit gate for Loss-DiVincenzo (spin-½) qubits to achieve good performance. For hole-spin qubits, determining g-tensor elements is another relevant multiparameter estimation problem. We construct and analyze a protocol for information amplification that is applicable to general multiparameter estimation problems. Non-amplified strategies involve successive preparations, free evolutions, and measurements to estimate, e.g., the exchange and Overhauser gradient. In contrast, we consider a protocol involving a sequence of interlaced unitaries that amplifies information about the parameters to be estimated, in direct analogy with noise spectroscopy, where specific Fourier components of the noise spectral density can be amplified through a sequence of pi-pulses. A comparison between the entropy (parameter uncertainty) achieved through amplified and non-amplified protocols is given in Fig. 1. Entropy is favored over the variance as a measure of uncertainty when the associated probability distributions are multi-modal.
PhD student, McGill University
Director: Tami Pereg-Barnea
Learning shadows to predict quantum ground state correlations
We introduce a variational scheme inspired by classical shadow tomography to compute ground state correlations of quantum spin Hamiltonians. Shadow tomography allows for efficient reconstruction of expectation values of arbitrary observables from a bag of repeated, randomized measurements, called snapshots, on copies of the state. The prescription allows one to infer expectation values of local observables using a number snapshots that scales polynomially with system size when measurements are performed in locally random bases. Turning this around, a bag of snapshots can be considered an efficient representation of the state , particularly for estimating low-weight observables, such as terms in a local Hamiltonian needed to estimate the energy. Inspired by this, we consider a variational scheme wherein a bag of parametrized snapshots is used to represent the putative ground state of a desired local spin Hamiltonian and optimized to lower the energy with respect to it. Additional constraints in the form of positivity of reduced density matrices, motivated by work in quantum chemistry, are employed to ensure compatibility of the predicted correlations with the underlying Hilbert space. Unlike reduced density matrix approaches, learning the underlying distribution of measurement outcomes allows one to further correlations beyond those in the constrained density matrix. We show, with numerical results, that the proposed variational method can be parallelized, is efficiently simulable, and yields a more complete description of the ground state.
PhD student, Polytechnique Montréal
Director: Sébastien Francoeur
Tittle to be annouced
PhD student, Université de Sherbrooke
Director: Mathieu Juan
Vector magnet control for on-chip magnonics