Year of Quantum Across Canada25th Anniversary

Oct 6, 2025, 8:00 AM → Oct 9, 2025, 5:00 PM America/Toronto

Perimeter Institute and Institute for Quantum Computing (IQC)

Year of Quantum Across Canada: From Fundamental Science to Applications

The Institute for Quantum Computing and the Perimeter Institute for Theoretical Physics will jointly host a meeting celebrating the 100 year anniversary of the discovery of quantum mechanics. 

The conference will celebrate and aim to strengthen the quantum information science community in Canada and beyond, by bringing together leading Canadian researchers as well as members of the broader quantum community. The program will highlight the fundamental advances being made in quantum information theory and how these advances lead to applications. 

 

Topics included in the program:

• Quantum metrology
• Quantum simulation and quantum advantage
• Quantum error-correction and fault tolerance
• Quantum complexity and algorithms
• Quantum communication and networks
• Quantum cryptography
• Quantum information in quantum matter and quantum gravity 
  
  

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Recorded Archive of Talks

Day 1 - Monday Oct 6 at IQC:
https://www.youtube.com/live/RXHSelMTHhU

Day 2 - Tuesday Oct 7 at IQC:
https://www.youtube.com/live/e5Qx7xuAMpQ

Day 3 and 4 - Wednesday Oct 8 and Thursday Oct 9 at Perimeter:
https://pirsa.org/c25033

 

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Speakers

Christian Bauer (Lawrence Berkeley National Laboratory)
Alexandre Blais (Université de Sherbrooke)
Sergey Bravyi (IBM Research - Thomas J. Watson Research Center)
Nikolas Breuckmann (University of Bristol)
Eric Chitambar (University of Illinois at Urbana-Champaign)
Soonwon Choi (MIT)
Zohreh Davoudi (University of Maryland)
Matthew Fisher (University of California, Santa Barbara)
Dakshita Khurana (University of Illinois Urbana-Champaign)
Aleksander Kubica (Yale University)
Hank Lamm (Fermilab)
Laura Mancinska (University of Copenhagen)
Antonio Mezzacapo (IBM)
John Preskill (Caltech)
Martin Savage (University of Washington)
Brian Swingle (Brandeis University)
Nathan Wiebe (University of Toronto)
Yu-Xiang Yang (The University of Hong Kong)

Co-Chairpersons

Marcela Carena (Perimeter Institute & University of Chicago & Fermilab)
Norbert Lütkenhaus (University of Waterloo, Institute for Quantum Computing)

Scientific Organizers and Convenors

Alexandre Blais (Université de Sherbrook)
Anne Broadbent (University of Ottawa)
Shohini Ghose (Wilfrid Laurier University & Quantum Algorithms Institute)
David Gosset (University of Waterloo, IQC, Perimeter Institute) 
Tim Hsieh (Perimeter Institute)
Ray Laflamme (University of Waterloo, IQC)
Alex May (Perimeter Institute)
Christine Muschik (University of Waterloo, IQC, Perimeter Institute) 
John Preskill (CalTech)
Barry Sanders (University of Calgary & Quantum City) 
Aephraim Steinberg (University of Toronto, CQIQC)
Beni Yoshida (Perimeter Institute) 
Peter Zoller (University of Innsbruck & IQOQI)
Sisi Zhou (Perimeter Institute)

Mon, October 6

8:30 AM Registration

1 Opening Remarks

2 Plenary Talk: Quantum Simulation for High Energy Physics

After motivating the need for quantum simulation in High Energy Physics, I will explain one of the main tools for such simulations, namely a Hamiltonian formulation of lattice gauge theory. I will explain several general concepts, before focusing on the development of an efficient representation of the lattice Hamiltonian for QCD, the theory of the strong interaction. Time permitting, I will conclude with a few remarks about truncations of bosonic Hilbert spaces.

Speaker: Christian Bauer (Lawrence Berkeley National Laboratory)

Perimeter Talk.key

Perimeter Talk.pdf

3 Plenary Talk: Monitoring Quantum Dynamics

Traditionally, quantum condensed matter theory has focussed on ground states and equilibrium properties of spatially extended systems, such as electrons and spins in crystalline solids. In recent years noisy intermediate scale quantum computers" have emerged, providing new opportunities for controllable non-equilibrium many-body dynamics. In such dynamical quantum systems the inexorable growth of quantum entanglement is expected, butmonitoring" (by making measurements) can compete against entanglement growth. In this talk I will overview work exploring the behavior of such monitored" quantum dynamics, which can exhibit measurement-induced phase transitions (MIPT), for example between volume law and area law entanglement. Experimental verification of these MIPT's can be challenging due to the so-called “post-selection problem”, but can be circumnavigated employing classical-quantumdecoding". Employing this approach, recent experiments have observed the MIPT, as I will briefly describe.

Speaker: Matthew Fisher (UC Santa Barbara)

Matthew_Fisher_Perimeter_Monitored.pdf

10:45 AM Break

Contributed Talks

4 Choi-defined resource theories

Many resource theories share an interesting property: An operation is free if and only if its renormalized Choi matrix is a free state. In this article, we refer to resource theories exhibiting this property as Choi-defined resource theories. We demonstrate how and under what conditions one can construct a Choi-defined resource theory, and we prove that when such a construction is possible, the free operations are all and only the completely resource-nongenerating operations. Moreover, we examine resource measures, a complete family of monotones, and conversion distances in such resource theories.

Speaker: Carlo Maria Scandolo (University of Calgary)

Carlo Maria_Scandolo_CDRT_presentation_IYQC.pdf

5 Uncloneable Encryption from Decoupling

We show for the first time that uncloneable encryption exists with no computational assumptions, with security inverse-polynomial in the security parameter. We use properties of a monogamy-of-entanglement game associated with the Haar measure encryption to guarantee that any state that succeeds with high probability cannot be close to maximally-entangled between the referee and either of the players, whence we can apply the decoupling principle to show that either player becomes completely uncorrelated, and therefore cannot win significantly better than random guessing.

Speaker: Archishna Bhattacharyya (University of Ottawa)

Archishna_Bhattacharyya_Slides_AB_UE from decoupling.pdf

6 Quantum Pseudoentanglement and its Applications within the AdS/CFT Correspondence

Quantum pseudoentanglement is a property of certain quantum systems where specific ensembles of quantum states are indistinguishable from maximally entangled states. The construction of quantum pseudoentanglement requires pseudorandom quantum states that can be efficiently generated but are indistinguishable from Haar-random states. Specifically, we construct pseudoentangled states whose entanglement entropy across every bipartition is arbitrarily close to log(n), establishing a tight bound that reveals an exponential separation between computational and information-theoretic notions of quantum pseudorandomness. Using this framework, we aim to demonstrate a natural manifestation of quantum pseudoentanglement in specific AdS/CFT holographic theories. In particular, we will construct pseudoentangled states within boundary conformal field theories (CFTs) by imposing constraints on the CFT spectrum and will investigate the corresponding bulk dynamics. We refer to this approach as the phase state construction of pseudoentanglement. In addition, we introduce an alternative formulation—the subset construction—in which pseudoentangled states are generated as finite superpositions of select complete boundary thermal ensembles, such as the thermofield double state. We analyze the bulk duals of these constructions to understand their implications for bulk dynamics, including the computational hardness of learning bulk operators and the conditions under which phenomena like the conjectured Python’s lunch emerge. Finally from this analysis, we will also aim to deduce characteristics of the computational complexity class associated with the holographic map and advance our understanding of bulk reconstruction from current constructions using the Petz map.

Speaker: Murtaza Jafry (University of Chicago)

12:00 PM Lunch

7 The mysterious case of qubit readout in circuit QED

Circuit quantum electrodynamics (cQED) has emerged as a powerful platform for quantum computation and for the investigation of quantum optics at microwave frequencies. A critical part of all cQED experiments is qubit readout, which relies on microwave drives. In principle, higher drive amplitudes should lead to faster and more accurate readout. However, experiments have consistently shown that as the drive amplitude increases, the readout quality rapidly deteriorates, something that severely limits qubit readout in the laboratory. We begin by reviewing the basics of qubit measurement in circuit QED, followed by presenting numerical simulations that capture the dynamics of the readout process. Our findings reveal signatures of ‘qubit ionization’, where the qubit is brought to highly excited states by the readout drive, leading to a breakdown of the measurement fidelity. Building on previous theoretical and experimental advances, we present a comprehensive theoretical framework providing a physical picture of the origin of transmon ionization, together with a set of tools which can readily be used to predict its occurrence. We further discuss how this phenomenon is not limited to qubit readout but also manifests itself in strongly driven nonlinear circuits across various settings. Finally, we compare our results with recent experimental data.

Speaker: Alexandre Blais (Institut quantique, Université de Sherbrooke)

8 Quantum simulation of nonequilibrium dynamics for nuclear and particle physics

The universe has evolved from a far-from-equilibrium state at the Big Bang. High-energy particle colliders aim to recreate such nonequilibrium conditions in experiment, to reach densities and temperatures necessary for generating some of the most short-lived states of matter, and to unravel equilibration and hadronization mechanisms. Theoretical studies of matter out of equilibrium, rooted in the fundamental gauge theories of nature, often require simulations that are intractable with classical computing. Quantum simulators have started to probe out-of-equilibrium physics of quantum many-body systems in recent years. They have further shown promise in probing gauge-theory dynamics, and continue to grow in scale, complexity, and relevance. We review recent theoretical and experimental developments at this frontier, with a focus on gauge-theory nonequilibrium phenomena such as string breaking and particle production, hadron-collision dynamics, and thermalization.

Speaker: Zohreh Davoudi (University of Maryland, College Park)

QC-gauge-theories-ZD-Oct-2025.pdf

2:30 PM Break

9 Panel Discussion: Quantum Algorithm – research directions and perspective

Moderator
Alexandre Blais

Panelists
David Gosset
John Preskill

Speakers: Alexandre Blais (Institut quantique, Université de Sherbrooke), David Gosset (University of Waterloo - Institute for Quantum Computing (IQC)), Graeme Smith (Institute for Quantum Computing (AMATH)), John Preskill (California Institute of Technology (Caltech) - Division of Physics Mathematics & Astronomy)

10 Discussion

5:00 PM Welcome Reception / Lab Tours

Tue, October 7

11 Quantum reductions for nonlocal games (Plenary Talk)

Gap-preserving reductions are central to classical complexity theory, but their quantum counterparts, especially in the setting of multiprover interactive proofs with entangled provers, present new challenges. In this talk I will introduce a framework for such reductions in the MIP setting and use it to show that the gapped promise problem for independent set games is MIP-complete. These games, with constant question size, are solvable in polynomial time in the classical case yet can be undecidable in the quantum case. A central technical ingredient is a new stability theorem that transforms nearly projective measurements into exact ones.

Speaker: Laura Mančinska (University of Copenhagen)

Laura_Mancinska_Main.pdf

12 Building Spacetime From Quantum Information

Quantum information has proven extremely useful for understanding how spacetime emerges from microphysics in some quantum theories of gravity. Conversely, quantum gravity has inspired a number of ideas and tools of broader relevance for quantum information science. I will describe one recent example of this exchange in which we used ideas of quantum randomness and tensor networks to shed light on the nature of the interior of black holes.

Speaker: Brian Swingle (Brandeis University)

Brian_Swingle_year of quantum across canada.pdf

Contributed Talks

13 The Clifford hierarchy for one qubit or qudit

The Clifford hierarchy is a nested sequence of sets of quantum gates that can be fault-tolerantly performed using gate teleportation within standard quantum error correction schemes. Non-Clifford gates from the third level or higher, e.g. the $T$ gate, are necessary for achieving fault-tolerant universal quantum computation. Since it was defined twenty-six years ago by Gottesman-Chuang [4], two questions have been studied by numerous researchers. First, precisely which gates constitute the Clifford hierarchy? Second, which hierarchy gates admit efficient gate teleportation protocols? We completely solve both questions in the case of the Clifford hierarchy for gates of one qubit or one qudit of prime dimension. Our results are the first to answer these questions while varying both the qudit dimension $d$ and the hierarchy level $k$.

A particularly important subset of the hierarchy are the semi-Clifford gates, which admit a more efficient gate teleportation protocol than other hierarchy gates. We show that every gate in the one-qudit hierarchy is semi-Clifford and thus may be implemented efficiently. This result allows us to give a normal form for gates in the hierarchy, expressing each gate uniquely as the product of three simple gates. This precisely characterizes the gates of the one-qubit/qudit hierarchy, and additionally yields a formula for the number of gates at each level of the hierarchy.

Our main theoretical tools include the technique of conjugate tuples: to each gate $G$ we associate the conjugate tuple of $2n$ gates $\{(GZ_iG^*, GX_iG^*)\}_{1\leq i\leq n}$, and it was shown by de Silva [3], extending Beig-Shor [1], that gates in the hierarchy are best understood in terms of this tuple. Another key tool is an action of the symplectic group on the group of unitaries $\mathcal{U}$: the Clifford group, modulo phase and Paulis, is isomorphic to the symplectic group $Sp(n, \mathbb{Z}_d)$. The action of the Clifford group on $\mathcal{U}$ by conjugation then induces an action of $Sp(n, \mathbb{Z}_d)$ on $\mathcal{U}$, and this action is best understood by writing matrices in the Pauli basis. Using this, we show that semi-Clifford gates have a nice geometric description in terms of the Pauli basis, which is a key step in our proof.

Our results significantly advance the program of classifying the Clifford hierarchy and semi-Clifford gates. Deeper understanding of these gate sets allows for progress in error correction and fault-tolerance, as well as more efficient circuit and gate synthesis. Our findings are particularly relevant to the qudit case, which is practically important as qudit magic state distillation may provide a significantly more efficient alternative to the qubit case [2].

References:
[1] S. Beigi and P. W. Shor. C3, semi-Clifford and generalized semi-Clifford operations. Quantum Information and Computation, 10(1):41–59,2010.
[2] E. T. Campbell, H. Anwar, and D. E. Browne. Magic-state distillation in all prime dimensions using quantum Reed-Muller codes. Physical Review X, 2:041021, 2012.
[3] N. de Silva. Efficient quantum gate teleportation in higher dimensions. Proceedings of the Royal Society A, 2021.
[4] D. Gottesman and I. L. Chuang. Quantum teleportation is a universal computational primitive. Nature, 402(6760):390–393, 1999.

Speaker: Oscar Lautsch (University of Waterloo, Department of Pure Mathematics & Institute for Quantum Computing)

14 A Cautionary Note on Quantum Oracles

In recent years, the quantum oracle model introduced by Aaronson and Kuperberg (2007) has found a lot of use in showing oracle separations between complexity classes and cryptographic primitives. It is generally assumed that proof techniques that do not relativize with respect to quantum oracles will also not relativize with respect to classical oracles. In this note, we show that this is not the case: specifically, we show that there is a quantum oracle problem that is contained in the class QMA, but not in a class we call polyQCPH. The class polyQCPH is equal to PSPACE with respect to classical oracles, and it is a well-known result that QMA is contained in PSPACE (also with respect to classical oracles).

We also show that the same separation holds relative to a distributional oracle, which is a model introduced by Natarajan and Nirkhe (2024). We believe our findings show the need for some caution when using these non-standard oracle models, particularly when showing separations between quantum and classical resources.

Speaker: Avantika Agarwal (Institute for Quantum Computing)

Avantika_Agarwal_Cautionary Note on Quantum Oracles.pdf

10:45 AM Break

Contributed Talks

15 Hiding, Shuffling, and Cycle Finding: Quantum Algorithms on Edge Lists

The edge list model is arguably the simplest input model for graphs, where the graph is specified by a list of its edges. In this model, we study the quantum query complexity of three variants of the triangle finding problem. The first asks whether there exists a triangle containing a target edge and raises general questions about the hiding of a problem's input among irrelevant data. The second asks whether there exists a triangle containing a target vertex and raises general questions about the shuffling of a problem's input. The third asks whether there exists a triangle; this problem bridges the $3$-distinctness and $3$-sum problems, which have been extensively studied by both cryptographers and complexity theorists. We provide tight or nearly tight results for these problems as well as some first answers to the general questions they raise.

Furthermore, given any graph with low maximum degree, such as a typical random sparse graph, we prove that the quantum query complexity of finding a length-$k$ cycle in its length-$m$ edge list is $m^{3/4-1/(2^{k+2}-4)\pm o(1)}$, which matches the best-known upper bound for the quantum query complexity of $k$-distinctness on length-$m$ inputs up to an $m^{o(1)}$ factor. We prove the lower bound by developing new techniques within Zhandry's recording query framework [CRYPTO '19] as generalized by Hamoudi and Magniez [ToCT '23]. These techniques extend the framework to treat any non-product distribution that results from conditioning a product distribution on the absence of rare events. We prove the upper bound by adapting Belovs's learning graph algorithm for $k$-distinctness [FOCS '12]. Finally, assuming a plausible conjecture concerning only cycle finding, we show that the lower bound can be lifted to an essentially tight lower bound on the quantum query complexity of $k$-distinctness, which is a long-standing open question.

Speaker: Xingyu Zhou (The University of British Columbia)

Xingyu_Zhou_YQAC__cycle_finding.pdf

16 Extendibility of Fermionic Gaussian States

We investigate $(k_1,k_2)$-extendibility of fermionic Gaussian states, a property central to quantum correlations and approximations of separability. We show that these states are $(k_1,k_2)$-extendible if and only if they admit a fermionic Gaussian extension, yielding a complete covariance-matrix characterization and a simple semidefinite program (SDP) whose size scales linearly with the number of modes. This provides necessary conditions for arbitrary fermionic states and is sufficient within the Gaussian setting. Our main result is a finite de Finetti--type theorem: we derive trace-norm bounds between $(k_1,k_2)$-extendible fermionic Gaussian states and separable states, improving previous exponential scaling to linear in the number of modes, with complementary relative entropy and squashed entanglement bounds. For two modes, upper and lower bounds match at order $1/\sqrt{k_1 k_2}$. Extendibility also provides operational support for one of the different notions of separability in fermionic systems. Finally, for fermionic Gaussian channels, we provide an SDP criterion for anti-degradability and show that entanglement-breaking channels coincide with replacement channels, implying no nontrivial entanglement-breaking fermionic Gaussian channels exist.

Speaker: Amirreza Negari (Perimeter Institute for Theoretical Physics)

17 Classical Simulability of Quantum Circuits with Shallow Magic Depth

Quantum magic is a necessary resource for quantum computers to be not efficiently simulable by classical computers. Previous results have linked the amount of quantum magic, characterized by the number of 𝑇 gates or the stabilizer rank, to classical simulability. However, the effect of the distribution of quantum magic on the hardness of simulating a quantum circuit remains open. In this work, we investigate the classical simulability of quantum circuits with alternating Clifford and 𝑇 layers across three tasks: amplitude estimation, sampling, and evaluating Pauli observables. In the case in which all 𝑇 gates are distributed in a single layer, performing amplitude estimation and sampling to multiplicative error are already classically intractable under reasonable assumptions, but Pauli observables are easy to evaluate. Surprisingly, with the addition of just one 𝑇-gate layer or merely replacing all 𝑇 gates with 𝑇^{1/2}, the Pauli evaluation task reveals a sharp complexity transition from being in P to being GapP-complete. Nevertheless, when the precision requirement is relaxed to 1⁢/poly⁢(𝑛) additive error, we are able to give a polynomial-time classical algorithm to compute amplitudes, Pauli observables, and sampling from log(𝑛)-sized marginal distributions for any magic-depth-1 circuit that is decomposable into a product of diagonal gates. This rules out certain forms of quantum advantage in these circuits. Our research provides new techniques to simulate highly magical circuits while shedding light on their complexity and their significant dependence on the magic depth.

Speaker: Yuxuan Zhang (University of Toronto)

Yuxuan_Zhang_Shallow T Depth_YQAC.pdf

12:00 PM Lunch

1:30 PM Discussion / Collaboration Time

2:30 PM Break

18 Quantum Simulation of Fundamental Physics

Speaker: Martin Savage (University of Washington)

Savage_Canada_October2025_v1p5_pdf.pdf

19 Optimal quantum metrology under energy constraints

Quantum metrology promises enhanced precision in parameter estimation by exploiting quantum effects. The traditional framework of metrology commonly assumes unlimited access to resources, overlooking resource constraints in realistic scenarios. As such, the optimal strategies therein are often infeasible in practice. In this talk, I will introduce our recent result on optimal quantum metrology where the total energy consumption of the probe state preparation, intermediate control operations, and the final measurement is subject to an energy constraint. The result is built on a comprehensive theoretical framework for characterizing energy-constrained quantum multi-step processes, which can be applied to other tasks of quantum information processing beyond metrology. Based on the framework, we develop a general optimization method for energy-constrained quantum metrology that determines the optimal precision as well as the corresponding optimal strategy. Based on arXiv 2506.09436.

Speaker: Yuxiang Yang (University of Hong Kong (HKU))

Yuxiang_Yang_YYang_Energy_Metrology.pdf

20 Discussion

5:00 PM Poster Session / Lab Tours

21 Public Event - Panel Discussion: Impact of Quantum Information Science: how will it change how we work? (RSVP Recommended)

Moderator
Roger Melko

Panelists
Antionio Mezzacapo
Christine Muschik
Martin Savage
Brian Swingle

Please RSVP in advance here: https://uwaterloo.ca/institute-for-quantum-computing/events/impact-quantum-information-science-how-will-it-change-how-we

Speakers: Roger Melko (University of Waterloo - Department of Physics and Astronomy), Antonio Mezzacapo (IBM Research - Thomas J. Watson Research Center), Christine Muschik (University of Waterloo), Martin Savage (University of Washington), Brian Swingle (Brandeis University)

Wed, October 8

22 Quantum Computing Enhanced Sensing (Plenary Talk)

Quantum computing and sensing represent two distinct frontiers of quantum information science. Here, we harness quantum computing to solve a fundamental and practically important sensing problem: the detection of weak oscillating fields with unknown strength and frequency. We present a quantum computing enhanced sensing protocol, that we dub quantum search sensing, outperforming all existing approaches. Furthermore, we prove our approach is optimal by establishing the Grover-Heisenberg limit -- a fundamental lower bound on the minimum sensing time. The key idea is to robustly digitize the continuous, analog signal into a discrete operation, which is then integrated into a quantumalgorithm. Our metrological gain originates from quantum computation, distinguishing our protocol from conventional sensing approaches. Indeed, we prove that broad classes of protocols based on quantum Fisher information, finite-lifetime quantum memory, or classical signal processing are strictly less powerful. We propose and analyze a proof-of-principle experiment using nitrogen-vacancy centers, where meaningful improvements are achievable using current technology. This work establishes quantum computation as a powerful new resource for advancing sensing capabilities.

Speaker: Soonwon Choi (MIT)

Soonwon_Choi_talk_QSS_PI.pdf

Talk Recording (25100049)

23 Topological Quantum Spin Glass Order

Ordered phases of matter have close connections to computation. Two prominent examples are spin glass order, with wide-ranging applications in machine learning and optimization, and topological order, closely related to quantum error correction. Here, we introduce the concept of topological quantum spin glass (TQSG) order which marries these two notions, exhibiting both the complex energy landscapes of spin glasses, and the quantum memory and long-range entanglement characteristic of topologically ordered systems. Using techniques from coding theory and a quantum generalization of Gibbs state decompositions, we show that TQSG order is the low-temperature phase of various quantum LDPC codes on expander graphs, including hypergraph and balanced product codes. Our work introduces a topological analog of spin glasses that preserves quantum information, opening new avenues for both statistical mechanics and quantum computer science.

Speaker: Nikolas Breukmann (University of Bristol)

Nikolas_Breuckmann_Breuckmann - Topological Quantum Spin Glass.pdf

Talk Recording (25100050)

24 Harnessing qudits for quantum simulations

Particle physics underpins our understanding of the world at a fundamental level by describing the interplay of matter and forces through gauge theories. Yet, despite their unmatched success, the intrinsic quantum mechanical nature of gauge theories makes important problem classes notoriously difficult to address with classical computational techniques. A promising way to overcome these roadblocks is offered by quantum computers, which are based on the same laws that make the classical computations so difficult. We present a quantum computation of the properties of the basic building block of two-dimensional lattice quantum electrodynamics, involving both gauge fields and matter. This computation is made possible by the use of a trapped-ion qudit quantum processor, where quantum information is encoded in  d  different states per ion, rather than in two states as in qubits. Qudits are ideally suited for describing gauge fields, which are naturally high-dimensional, leading to a dramatic reduction in the quantum register size and circuit complexity. Our results open the door for hardware-efficient quantum simulations with qudits in near-term quantum devices.

Speaker: Christine Muschik (University of Waterloo - Institute for Quantum Computing (IQC))

Talk Recording (25100051)

10:45 AM Break

Contributed Talks

25 Chiral Color Code : Single-shot error correction for exotic topological order

We present a family of simple three-dimensional stabilizer codes, called the chiral color codes, that realize fermionic and chiral topological orders. In the qubit case, the code realizes the topological phase of a single copy of the fermionic toric code. For qudit systems with local dimension d, the model features a chiral parameter α and realizes 3D topological phases characterized by $\mathbb{Z}^\alpha_d$ anyon theories with anomalous chiral surface topological order. On closed manifolds, the code has a unique ground state after removing bulk transparent fermions or bosons. Furthermore, we prove that the bulk is short-range entangled (for odd d, coprime α) by constructing an explicit local quantum channel that prepares the ground state. The chiral color codes are constructed within the gauge color code, and hence inherit its fault-tolerant features: they admit single-shot error-correction and allow code switching to other stabilizer color codes. These properties position the chiral color codes as particularly useful platforms for realizing and manipulating fermions and chiral anyons.

Speaker: Dongjin Lee (Perimeter Institute for Theoretical Physics)

Dongjin_Lee_Slides_Dongjin.pdf

Talk Recording (25100151)

26 Architectural mechanisms of a universal fault-tolerant quantum computer

Quantum error correction (QEC) is believed to be essential for the realization of large-scale quantum computers. However, due to the complexity of operating on the encoded `logical' qubits, understanding the physical principles for building fault-tolerant quantum devices and combining them into efficient architectures is an outstanding scientific challenge. Here we utilize reconfigurable arrays of up to 448 neutral atoms to implement all key elements of a universal, fault-tolerant quantum processing architecture and experimentally explore their underlying working mechanisms. We first employ surface codes to study how repeated QEC suppresses errors, demonstrating 2.14(13)x below-threshold performance in a four-round characterization circuit by leveraging atom loss detection and machine learning decoding. We then investigate logical entanglement using transversal gates and lattice surgery, and extend it to universal logic through transversal teleportation with 3D [[15,1,3]] codes, enabling arbitrary-angle synthesis with logarithmic overhead. Finally, we develop mid-circuit qubit re-use, increasing experimental cycle rates by two orders of magnitude and enabling deep-circuit protocols with dozens of logical qubits and hundreds of logical teleportations with [[7,1,3]] and high-rate [[16,6,4]] codes while maintaining constant internal entropy. Our experiments reveal key principles for efficient architecture design, involving the interplay between quantum logic and entropy removal, judiciously using physical entanglement in logic gates and magic state generation, and leveraging teleportations for universality and physical qubit reset. These results establish foundations for scalable, universal error-corrected processing and its practical implementation with neutral atom systems.

Speaker: Shayan Majidy (Princeton University)

Talk Recording (25100149)

27 Decoding Multimode Gottesman-Kitaev-Preskill Codes with Noisy Auxiliaries

In order to achieve fault-tolerant quantum computing, we make use of quantum error correction schemes designed to protect the logical information of the system from decoherence. A promising way to preserve such information is using the multimode Gottesman-Kitaev-Preskill (GKP) encoding, which encodes a single logical qubit into harmonic oscillators. This type of encoding adds redundancy in the physical system by leveraging the infinitely large Hilbert space of multiple oscillators. Such redundancy can be used to increase the distance between the logical code words, protecting the logical qubit against larger errors. Usual protocols to correct multimode GKP states are based on Steane-type quantum error correction circuits. Steane-type circuits consist of auxiliary state preparation, two-mode squeezing operations, measurements and decoding. In this work, we focus on the decoding part of these protocols. More precisely, we propose a decoder that considers the noise present on the auxiliary states. Specifically, we do so by tracking the correlations between errors on different modes spreading throughout the circuit which represents the Steane-type protocol. We show that leveraging the correlations between the measurement result and the actual error affecting the multimode GKP state enables less decoding errors. Overall, for each different multimode GKP code studied, we can increase the lifetime by at least an order of magnitude, yielding more robust quantum computation.

Speaker: Marc-Antoine Roy (Université de Sherbrooke)

Marc-Antoine_Roy_yqac_pres_marcantoineroy.pdf

Talk Recording (25100150)

12:00 PM Lunch

1:30 PM Discussion / Collaboration Time

2:30 PM Break

28 Keynote: Our Quantum Future

Speaker: John Preskill (Caltech)

Talk Recording (25100052)

29 Discussion

Discussion Recording

6:00 PM Banquet Dinner

Thu, October 9

30 Layer codes as partially self-correcting quantum memories (Plenary Talk)

Speaker: Aleksander Kubica (Yale University)

Talk Recording (25100054)

31 Is Fundamental Physics Fundamentally Simpler?

Speaker: Nathan Wiebe (University of Toronto)

Talk Recording (25100055)

32 Chemistry beyond the scale of exact diagonalization on a quantum-centric supercomputer

In this talk, I will discuss quantum diagonalization methods, based on subspaces obtained from quantum computers, which overcome the scaling limitations of variational algorithms and enabled realistic chemistry computations of up to 77 qubits on a quantum centric supercomputing architecture, using a Heron quantum processor and the RIKEN supercomputer Fugaku. Merging these ideas with Krylov quantum subspaces, I will present a ground state algorithm with convergence similar to phase estimation and robustness to noise, which led to an experimental demonstration for lattice ground state problems obtained with Heron processors and the supercomputer Frontier.

Speaker: Antonio Mezzacapo (IBM Research - Thomas J. Watson Research Center)

Talk Recording (25100056)

10:45 AM Break

33 Building bridges between entanglement and coherence

In distributed quantum information processing, the parties are often limited to performing local operations and classical communication (LOCC). The class of LOCC is notoriously difficult to analyze, and typically one considers the larger class of so-called separable (SEP) operations, which has a nicer mathematical structure. Finding separable but non-LOCC maps is a challenging endeavor, with most known examples involving the task of state discrimination. In this talk, I will describe an approach for constructing SEP but non-LOCC channels based on the resource theory of quantum coherence. This further highlights the value of studying general resource theories within quantum information theory. This is joint work with Ludovico Lami.

Speaker: Eric Chitambar (University of Illinois Urbana-Champaign)

Eric_Chitambar_PI-2025-Entanglement-Coherence.pdf

Talk Recording (25100057)

12:00 PM Lunch

34 How Low Can We Go? Exploring Minimal Assumptions in Quantum Cryptography

In this talk, I will explore the fascinating landscape of minimal assumptions in quantum cryptography—how little we need to assume to build secure quantum protocols. We will cover key cryptographic primitives including quantum encryption, signatures, and money, and show how these primitives imply the existence of one-way puzzles, a quantum analogue of classical one-way functions. I will also highlight the utility of one-way puzzles and discuss concrete assumptions that enable their realization, revealing intriguing connections with quantum advantage.

Speaker: Dakshita Khurana (University of Illinois Urbana-Champaign)

Talk Recording (25100139)

35 Quantum simulation of a noisy classical nonlinear dynamics

We consider the problem of simulating dynamics of classical nonlinear dissipative systems with N>>1 degrees of freedom. To make the problem tractable for quantum computers, we add a weak Gaussian noise to the equation of motion and the initial state. Our main result is an end-to-end quantum algorithm for simulating the noisy dynamics of nonlinear systems satisfying certain sparsity and divergence-free conditions. For any constant nonzero noise rate, the quantum runtime scales polynomially with log(N), evolution time, inverse error tolerance, and the relative strength of nonlinearity and dissipation.

Speaker: Sergey Bravyi (IBM Quantum, IBM T.J. Watson Research Center)

Sergey_Bravyy_bravyi_nonlinear_talk.pdf

Talk Recording (25100059)

2:30 PM Break

36 Panel Discussion: Academia & Companies - what is their role in driving quantum innovation forward?

Moderator
Martin Laforest

Panelists
Barry Sanders
Anne Broadbent
Vlad Gheorghiu
John Watrous

Speakers: Martin Laforest (Quantacet), Anne Broadbent (University of Ottawa), Barry Sanders (University of Calgary - The Institute for Quantum Science and Technology), Vlad Gheorgiu (University of Waterloo), John Watrous (IBM (Canada))

Talk Recording (25100060)

37 Discussion

Discussion Recording

38 Closing Remarks

Closing Remarks - Recording