11 octobre 2022

10:55 Mot d'ouverture(Salon A)

11:00 Bill Coish, McGill University (Salon A)
‍          Decoherence and open quantum systems

12:00 Diner (Salle Knowlton)

13:30 Ebrahim Karimi, Ottawa Universiy (Salon A)
‍          Structured Photons – Their Application inQuantum Photonics

14:30 Pause café (Salon C)

15:00 Martin Houde, Polytechnique Montréal (Salon A)
          Waveguided sources of consistent, single-temporal-mode squeezed light:
           the good, the bad, and the ugly

15:25 Sho Onoe, Polytechnique Montréal (Salon A)
          Simultaneous detection of field quadratures in the time-domain via
           electro-optic sampling

15:50 Denis Seletskiy, Polytechnique Montréal (Salon A)
          Canada-EU consortium on Mid-infrared quantum sensing

16h15 Mme Fran Delhoume (Salon A)
          Activité EDI : les microagressions sur le lieu de travail

17:15 Session d'affiches avec rafraichissements (Salon C)

19:30 Souper INTRIQ (Salle Knowlton)

October 12th, 2022

8:30 Chinmay Nirkhe, IBM quantum, Cambridge(Salon A)
          NLTS Hamiltonians from good quantum codes

9:30 Jonathan Durandau, Université de Sherbrooke (Salon A)
         Quantum Circuit Compilation and Quantum Computer Architecture

9:50 Pause café (Salon C)

10:20 Monika Aidelsburger, Munich University (Salon A)
         Quantum simulation of Floquet topological phases with ultracold atoms

11:20 Tami Pereg-Barnea, McGill University (Salon A)
          Majorana fermions, where to find them and how to use them

‍12:00 Diner (Sale Knowlton)

13:30 Roger Melko, Perimeter Institute (Salon A)
         Quantum Simulation and Rydberg Atom Arrays

14:30 Pause café (Salon C)

15:00 Karthik Chinni, Polytechnique Montréal (Salon A)
          Trotter  errors from dynamical structural instabilities of floquet maps
           in quantum  simulation

15:30 Michael Hilke, McGill University (Salon A)
          Molecular single photon sources for quantum communication
           and enhanced sensing

16:10 Mot de fermeture

‍Conférenciers invités

Pre Monika Aidelsburger

‍Quantum Optics Group
Munich University
Quantum simulation of Floquet topological phases with ultracold atoms
Well-controlled synthetic quantum systems, such as ultracold atoms in optical lattices, offer intriguing possibilities to study complex many-body problems in regimes that are beyond reach using state-of-the-art classical computations. The basic idea is to construct and use a well-controlled quantum many-body system in order to study its in- and out-of-equilibrium properties and potentially use it to develop more efficient tailored numerical methods that can then be applied to other systems that are not directly accessible with the simulator.

An important future quest concerns the development of novel experimental techniques that allow us to expand the range of models that can be accessed. I will demonstrate this using the example of topological lattice models, which in general do not naturally appear in cold-atom experiments. I will show how the technique of periodic driving, also known as Floquet engineering, facilitates their realization and show how charge-neutral atoms in lattices can mimic the behavior of charged particles in the presence of an external magnetic field. A key ingredient for quantum simulation is the degree of control one has over the individual particles and the microscopic parameters of the model. We have recently succeeded to not only use the technique of periodic driving to emulate physical systems that we know exist in nature, but to take this idea one step further and realize completely new topological regimes that do not have any static analog.

Pr Ebrahim Karimi

Department of Physics
University of Ottawa
Structured Photons – Their Application in Quantum Photonics
Photons, the quanta of light, possess several different degrees of freedom, e.g., frequency, polarisation, spatial and temporal modes, which can be used as platforms for quantum information applications. Polarisation, corresponding to the vectorial nature of light, is bi-dimensional, and thus can represent ‘0’ and ‘1’ in the digital world. Unlike polarisation, transverse and temporal modes would provide an unbonded vector space and could be used to extend the alphabet beyond the ‘0’s and ‘1’s to any arbitrary integer numbers. Photons in superposition states of these different degrees of freedom are known as Structured Photons. In the classical regime, structured light has found tremendous applications, e.g., overcoming the diffraction limit (STED microscopy), for optical spanners, communication multiplexing, and generating non-trivial 3D topologies such as Möbius, ribbons and knots. In the quantum domain, structured photons may be used to realise higher-dimensional states, and thus are employed in quantum communication, computation, and simulation applications.

The recent progress, challenges, and applications of structured photons in modern photonics, as well as their applications in high-dimensional quantum communication, e.g., free-space, underwater, fibre and curved spacetime, links and their security analysis, will be the subject of my talk.

Mme. Fran Delhoume, M.Sc.

Activité EDI : les microagressions sur le lieu de travail
Diplômée d'une maîtrise en développement organisationnel à HEC Montréal et d’unprogramme court en gestion de l'équité-diversité-inclusion (EDI) au travail de l’UQAR, Fran est formatrice en neuroinclusion en plus de collaborer comme analyste EDI avec la firme-conseil URelles et d'œuvrer comme chargée de cours à l’Université de Sherbrooke. Son mémoire, reçu avec mention, remet en question les fondements sous-jacents des pratiques d'inclusion professionnelle des personnes neurodivergentes. Elle est aussi co-animatrice du balado Les Neurodivertissantes qui a pour mission de vulgariser, démocratiser et partager les expertises et savoirs autour de la neurodiversité au travail.
‍

Malgréles efforts déployés en faveur de l'équité, de la diversité et de l'inclusion (EDI), les membres des groupes historiquement marginalisés continuent de faire l'objet de préjugés, d'inéquités, de microagressions et d'expériences discriminatoires dans le milieu de travail. Ces expériences, qui se déroulent au quotidien, sont liées à une baisse de la satisfaction au travail, à l'épuisement professionnel et la dépression, au désengagement professionnel, à un taux de rotation plus élevé et à d'autres problèmes sociaux et de santé. Des lieux de travail plus inclusifs sont au contraire associés à une plus grande satisfaction et rétention, à un meilleur engagement, à un sentiment d'appartenance plus élevé et à une innovation accrue. Dans cette présentation, nous donnons un aperçu compréhensif de ce que sont les microagressions et de leurs impacts. Nous examinons également le rôle et la responsabilité de l'écosystème et de ses membres face aux microagressions, ainsi que les stratégies qui peuvent être déployées aux niveaux individuel et organisationnel.

Pr Roger Melko

Perimeter Institute
Quantum Simulation and Rydberg Atom Arrays
One major goal of the current generation of quantum devices is to “simulate” (or emulate) the Hamiltonians found in condensed matter and material systems. Such quantum simulation strategies are particularly important in cases where it is challenging to simulate these systems with traditional computational tools, such as quantum Monte Carlo or tensor network methods - numerical schemes that have been under development for decades. Recently, the rapidly-advancing field of machine learning has introduced a host of new methods suitable for this task, involving neural network architectures and data-driven learning strategies.
In this talk, I will discuss the complementary role of experimental and in silico quantum simulations through the lens of machine learning, using the example of present-day Rydberg atom quantum computers. In particular, I will illustrate the utility of machine learning methods to leverage data from real experiments, and speculate on the future of scientific discovery in quantum many-body simulators that hybridize traditional and data-driven approaches.

Dr Chinmay Nirkhe

IBM quantum, Cambridge
NLTS Hamiltonians from good quantum codes
The quantum PCP conjecture is one of the central open questions in quantum complexity theory. It asserts that calculating even a rough approximation to the ground energy of a local Hamiltonian is intractable even for quantum devices. The widely believed separation between the complexity classes NP and QMA necessitates that polynomial length classical proofs do not exist for calculating the ground energy. This further implies that low-energy states of local Hamiltonians cannot be described by constant depth quantum circuits. 
The "Nolow-energy trivial states (NLTS)" conjecture by Freedman and Hastings posited the existence of such Hamiltonians. This talk will describe a line of research culminating in a proof of the NLTS conjecture by Anshu, Breuckmann, and Nirkhe. The construction is based on quantum error correction and in the talk, I will elaborate on how error correction, local Hamiltonians, and low-depth quantum circuits are related.

‍Conférenciers INTRIQ

Karthik Chinni

Postdoc, Polytechnique Montréal
Directeur: Nicolas Quesada
Trotter errors from dynamical structural instabilities of floquet maps in quantum simulation
We study the behavior of errors in the quantum simulation of spin systems with long-range multibody interactions resulting from the Trotter-Suzuki decomposition of the time-evolution operator. We identify a regime where the Floquet operator underlying the Trotter decomposition undergoes sharp changes even for small variations in the simulation step size. This results in a time evolution operator that is very different from the dynamics generated by the  targeted Hamiltonian, which leads to a proliferation of errors in the quantum simulation. These regions of sharp change in the Floquet operator, referred to as structural instability regions, appear typically at intermediate Trotter step sizes and in the weakly interacting regime, and are thus complementary to recently revealed quantum chaotic regimes of the Trotterized evolution. We characterize these structural instability regimes in p-spin models, transverse-field Ising models with all-to-all p-body interactions, and analytically predict their occurrence based on unitary perturbation theory. We further show that the effective Hamiltonian associated with the Trotter decomposition of the unitary time-evolution operator, when the Trotter step size is chosen to be in the structural instability region, is very different from the target Hamiltonian, which explains the large errors that can occur in the simulation in the regions of instability. These results have implications for the reliability of near-term gate-based quantum simulators, and reveal an important interplay between errors and the physical properties of the system being simulated.

Bill Coish

Professeur, McGill University
Decoherence and open quantum systems
In this talk, I will give a brief introduction to the physics of decoherence and quantum dynamics, along with methods for noise mitigation (e.g., dynamical decoupling). The emphasis will be on applications in spectroscopy, qubit readout, and quantum computing.

Jonathan Durandau

Doctorant, Université de Sherbrooke
Directeur: Yves Bérubé-Lauzière
Quantum Circuit Compilation and Quantum Computer Architecture
As the technology of qubit and the number of quantum algorithms grow, the next great objective of quantum engineering is an extensible quantum computer. Yet, multiple problems arise, the first one being the qubit connectivity problem. This problem is caused by different characteristics of the quantum qubit, such as the non-cloning theorem.
In this presentation, we will present and characterize the connectivity problem on two different types of qubits, superconducting and shuttled  trapped ions, using two existing machine as an example, the IBM computer and the Schmidt-Kaler group computer. We will analyze the connectivity of these machines and propose some solutions that we found in our research.

Michael Hilke

Professeur, McGill University
Molecular single photon sources for quantum communication and enhanced sensing

The pioneering experiments by Hanbury and Twiss are considered by many as the beginnings of quantum optics. These experiments are now particularly relevant in the context of quantum photonics and the characterization of single photon sources. After introducing these experiments and concepts, I will discuss molecular single photon sources, which are rapidly emerging as highly competitive contenders for quantum photonics. They combine the tunability and malleability typically associated with semiconductor based systems, such as quantum dots, and the high purity typically found in atomic systems. Here I will focus on a particular molecule/nanocrystal (BDT/antracene) hybrid system that exhibits a very high, on demand, single photon emission purity, even at room temperature. This system can easily be processed and integrated into various photonic and sensing applications. Two main applications will be discussed in more detail: (1)ambient quantum key distribution [1] with concrete advantages over conventional attenuated laser pulses and (2) local (10-100mnm) contact less temperature sensing at cryogenic temperatures. This is particularly interesting when all other techniques fail. This work was done in collaboration with the Toninelli group at LENS and theUniversity of Florence.

[1] G.Murtaza, et al. arXiv:2202.12635 (2022)

Martin Houde

Postdoc, Polytechnique Montréal
Directeur: Nicolas Quesada
Waveguided sources of consistent, single-temporal-mode squeezed light: the good, the bad, and the ugly
We study the oretically how the temporal mode structure of squeezed states generated by a parametric waveguided source is modified when driven by pumps of different brightness but identical profiles. We find that the temporal modes of these squeezed states are partially mismatched and thus distinguishable, which is undesirable when using these states as resources  for quantum computing or heralded state generation. By studying common frequency filtering techniques used experimentally, we find that although one can regain indistinguishability it comes at the price of potentially greatly reducing the purity of the state. We consider three different source configurations: unapodized single pass, apodized single pass, and apodized double pass. We find that the double pass configuration produces better results with more indistinguishable states.

Sho Onoe

Postdoc, Polytechnique Montréal
Directeur: Denis Seletskiy
Simultaneous detection of field quadratures in the time-domain via electro-optic sampling
Analysis of quantum optical states is typically performed using techniques of homodyne detection, where the superposition of the quantum state under study and a classical reference at the same frequency is registered in a square-law detector. Due to the lack of quantum-limited sources and efficient detectors, progress with the homodyne characterization of quantum states in the mid-infrared (mid-IR) has been stagnant. Recently, a technique of electro-optic sampling has established itself as the frontier of ultrafast photonics in the mid-infrared range, and recent experiments demonstrated the detection of mid-IR quantum fields, including bare vacuum, directly in the time domain. The temporal resolution comes from the duration of the gating function, commonly reaching 6 fs (1 fs = 10^-15 seconds). Here we consider a possibility to efficiently use the entire bandwidth of the gating function to accomplish simultaneous detection of both field quadratures. Motivated by the understanding of the mode structure of the amplitude and Hilbert transform quadratures, we propose multiplexing and mode-matching operations on the gating function to extract full quantum information on both quantities, simultaneously. The proposed experiment is poised to open a novel path toward quantum state tomography directly in the time domain, promising novel applications toward time-domain quantum spectroscopy and novel explorations in relativistic quantum information.

Tami Pereg-Barnea

Professeure. McGill University
Majorana  fermions, where to find them and how to use them
Majorana  fermions have been proposed as potential building blocks of qubits already in 1997.  However, despite many efforts to realize them in experiments, they have not been identified without doubt yet. In this tutorial we will go over some simple models of topological superconductivity which give rise to Majorana  fermions. We will also discuss proposals for realizing Majorana-hosting systems and Majorana-based qubits and discuss some recent experiments.

Denis Seletskiy

Professeur, Polytechnique Montréal
Sujet à venir

Session d'affiches

Aleksandr Berezutskii

Doctorant, Université de Sherbrooke
Directeur: Stéfanos Kourtis
Discrete optimization inthe MPS-MPO language
In discrete optimization problems, one usually asks for an optimal object from a finite set. Suchproblems appear in many fields ranging from logistics to quantum error correction. Many of these are NP-complete, making exact solutions too hard to find and thus leaving a battle field for different approximate algorithms. In the current study, we show how to marry such probblems with tensor networks and show several relevant example. The code for the study is available as a python package.

Ankita Chakravarty

Doctorant, Université de Sherbrooke
Directeur:  Michel Pioro-Ladrière
Sujet à venir

Eric Culf

Étudiant à la maîtrise, Université d'Ottawa
Directrice: Anne Broadbent
Coset State Uncloneability to Receiver-Independent QKD
We construct a receiver-independent quantum key distribution (QKD)scheme, which strengthens the notion of one-sided device independent QKD of Tomamichel, Fehr, Kaniewski, and Wehner [NJP 2013] by also permitting the receiver's classical device to be untrusted. Explicitly, the sender remains fully trusted while only the receiver's communication is trusted. We provide a construction that achieves the same asymptotic error tolerance as the scheme of Tomamichelet al.

To show security, we prove an extension of the MoE property of coset states introduced byColadangelo, Liu, Liu, and Zhandry [Crypto 2021]. In our stronger version, the player Charlie also receives Bob's answer prior to making his guess, thus simulating a party who eavesdrops on an interaction. To make use of this property, we express it as a new type of entropic uncertainty relation which arises naturally from the structure of the underlying MoE game.

Patrick Del Vecchio

Doctorant, Polytechnique Montréal
Directeur: Oussama  Moutanabbir
Sujet à venir

Alexandre Dumont

Doctorant, Université de Sherbrooke
Directeur: Bertrand Reulet

Fluctuation Loops in Microwave  circuits
‍Study of the out-of-equilibrium  properties of a circuit using thermal noise as a probe.

Clovis Farley

Étudiant à la maîtrise, Université de Sherbrooke
Directeur: Bertrand Reulet
Sujet à venir

Laurine Marian

Doctorante, Université de Sherbrooke
Directeur: Bertrand  Reulet
Detection of Higgs mode in a  superconducting wire via impedance measurements in the microwave domain
Microwave investigation of Higgs Mode in a superconducting wire. Higgs mode in superconductors is an analogous of the Higgs boson in high energy physics that has been predicted by Anderson in the late 50s [1]. Its detection is usually difficult because of its weak coupling with electromagnetic fields. However, a recent theory predicted a huge increase of this coupling in the presence of a DC current, which translates into an anomaly in the complex conductivity at frequencies of the order of 2Δ [2]. Observation of Higgs modes in superconductors have been performed in the THz range [3]. A study in the microwave range could enable new measurement such as non-local conductivity to probe its propagation. We studied Titanium samples for which 2Δ is of the order of 10-30 GHz and can be tuned with the sample thickness. In this experiment we present a precise and quantitative measurement of the high frequency complex impedance of a superconducting wire in the microwave range. In the absence of DC current, we compare our results with BCS theory at equilibrium. With current we observe a feature at frequency2Δ which behaves as predicted in [2] with a width much larger than expected. This experimentis the first step toward the integration of Higgs mode in electronic circuit.
[1] Anderson PW. 1958. Phys. Rev. 112:1900–16
[2] A. Moor and al., Amplitude Higgs Mode and Admittance in Superconductors  with a Moving Condensate, PRL 118, 047001 (2017)).
[3] Matsunaga R, Hamada YI, Makise K, Uzawa Y, Terai H, et al. 2013. Phys.  Rev. Lett. 111:057002

Javier Martínez

Doctorant, Polytechnique Montréal
Directeur: Nicolas Quesada
Validating the USTC Gaussian boson sampling experiment against classical mixtures of coherent states hypothesis
Recently,  Zhong et al. have performed Gaussian boson sampling experiments using  photonic circuits with up to 144 modes and threshold detectors. The samples  produced in these experiments have been validated against several classical  simulation strategies, such as sampling from probability distributions  corresponding to thermal states or distinguishable photons. In this work we  propose an alternative validation hypothesis that uses the probability  distribution of mixtures of coherent states sent into a lossy interferometer.  These mixtures result in classical Gaussian states with vacuum fluctuations in one quadrature and larger fluctuations in the other. To test this hypothesis, we compute the cumulants of the proposed distribution up to fourth order and compare them with the results obtained from the experimental  samples and the ground truth distribution of the experiment (namely, the  probability distribution of two-mode squeezed states sent into a lossy interferometer). We also calculate cross-entropy differences between the alternative and ground truth distributions, as well as between samples from the alternative distribution and experimental samples. We find that for the experiments with larger photon density, which are in the quantum advantage regime, the cumulants do not tell the ground state and alternative distributions apart. Additionally, the cross-entropy differences indicate that the alternative hypothesis is a better description of the experimental data than the ground truth hypothesis. These results suggest that the results of the experiment can be efficiently reproduced with classical sampling algorithms.

Zoé  McIntyre

Doctorante, McGill University
Directeur: Bill Coish
Non-Markovian transient  spectroscopy in cavity QED
We theoretically analyze measurements of the transient field leaving a cavity as a tool for studying  non-Markovian dynamics in cavity quantum electrodynamics (QED). Combined with  a dynamical decoupling pulse sequence, transient spectroscopy can be used to  recover spectral features that may be obscured in the stationary cavity transmission spectrum due to inhomogeneous broadening. The formalism  introduced here can be leveraged to perform in situ noise spectroscopy, revealing a robust signature of quantum noise arising from non-commuting observables,a purely quantum effect.

Andrew Mckenna

Stagiaire, McGill University
Directeur: Michael Hilke
Sujet à venir

Laurence  Mercier-Coderre

Étudiante à la maîtrise, Université de Sherbrooke
Directeur: Mathieu Juan
Sujet à venir

Gurleen Padda

Étudiante à la maîtrise, Université de Shebrooke
Directeur: Dave Touchette
Improving Qubit Routing with EPR Pairs

Joffrey Rivard

Doctorant, Université de Sherbrooke
Directrice: Eva Dupont-Ferrier
Sujet à venir

Marc-Antoine Roux

Doctorant, Université de Sherbrooke
Director: Michel Pioro-Ladrière
Real-time quantum dot stability diagram measurement using on-the-fly generated waveforms
Stability diagrams are essential  to understand the energy landscape of the quantum dots and tune them into the  spin-qubit regime, but the voltage space to cover increases significantly  with the number of quantum dots. While many advanced measurement techniques  were proposed in the last few years to minimize the number of measurements  needed to extract valuable information, another approach is to speed up the  measurements themselves. Therefore, Keysight’s Quantum Engineering Toolkit  (QET) was used to program the experimental routines inside the on-board  field-programmable gate arrays (FPGAs). While the programming of those  routines takes time and specific knowledge, they run with minimal  communications with the host computer which allows high processing speeds.  With this approach, we achieve stability diagram measurements in around 30 ms  and virtual gates calculations in under 100 ns. The flexibility of the FPGA  programming also allows the routines to be adapted to more complex  measurements that may include accelerated machine learning or statistical  models. Those tools are a first step towards the scalable control of spin  qubits using cryogenic electronics.

Pierre-Gabriel Rozon

Doctorant, McGill University
Directeur: Kartiek Agarwal
Sujet à venir

Romain Ruhlmann
Ankita Chakravarty

Professonel & Doctorante, Université de Sherbrooke
Directeur: Michel Pioro-Ladrière

& Maggie Wang

Stagiaire, McGill University
Directrice: Lilian Childress
Improving the Sensitivity of NV Magnetometry‍

Martin Schnee

Doctorant, Université de Sherbrooke
Directeur: Stéfanos Kourtis
Sujet à venir

Rigel Zifkin

Doctorant, McGill University
Director: Lilian Childress
Coupling Colour Centers in Diamond to Fiber Microcavities
Color centers in diamond are promising solid-state spin-qubit systems for quantum information thanks to their atom-like spin-optical properties. Two prospective candidates are the nitrogen-vacancy (NV) and germanium-vacancy (GeV). Current implementations with the NV center are restricted by its low emission rate (3%) into its coherent transition and spectral diffusion. In turn, the use of the GeV is limited by its spin-orbit interaction necessitating low-temperature operation. We present our current results in coupling a fiber-based open microcavity (measured finesse of F~8000) to a GeV at ~ 15K. Achieving a reduced lifetime of 1.7+/-0.1 ns (bare 6 ns) and an estimated Purcell Enhancement of the zero-phonon line of ~24.