Quantum Theory and Operator Theory 2025

August 24 - 29, 2025

Hosts

Beijing Institute of Mathematical Sciences and Applications (BIMSA)

Organizers

Zhengfeng Ji (Tsinghua University)

Chunlan Jiang (Hebei Normal University)

Zhengwei Liu (Tsinghua University)

Shunlong Luo (Academy of Mathematics and Systems Science, CAS)

Jinsong Wu (BIMSA)

Contact

Email: qtot@bimsa.cn

Location

A6 Lecture Hall 101, BIMSA Campus. [Amap] [Google Map]

No. 544 Hefangkou Village, Huairou, Beijing

北京市怀柔区河防口村544号金隅兴发科技园 101408

Dinning

BIMSA Campus A4 Dinning Hall

Tentative

Aug 25, 2025

Opening (9:30 ~ 9:40)
09:40 ~ 10:30 Chongying Dong (董崇英) Symmetries beyond group actions
Tea Break
10:50 ~ 11:40 Zhengwei Liu (刘正伟) Construct Planar Algebras by Classical and Quantum Computers
Lunch (A4 Hall)
13:30 ~ 14:20 Xiongfeng Ma (马雄峰) Measurement-Assisted Quantum Circuits: Circuit Complexity and Entanglement Generation
14:30 ~ 15:20 Li Ren (任丽) Reverse categories and reconstruction program
Tea Break
15:50 ~ 16:40 Kun Fang (方堃) Generalized quantum asymptotic equipartition and its applications
16:50 ~ 17:40 Zishuo Zhao (赵子烁) Bimodule Markov semigroups
Dinner (A4 Hall)

Aug 26, 2025

09:30 ~ 10:20 Naihuan Jing (景乃桓) Local unitary equivalence and hypermatrix algebra
Tea Break
10:50 ~ 11:40 You Zhou (周游) Robust and efficient estimation of global quantum properties under realistic noise
Lunch (A4 Hall)
13:30 ~ 14:20 Li Gao (高力) Convex Splitting: tight analysis and multipartite case
14:30 ~ 15:20 Dong An (安东) Quantum algorithms for matrix eigenvalue transformation
Tea Break
15:50 ~ 16:40 Ling-Yan Hung (孔令欣) A 2D-CFT Factory: Critical Lattice Models from Competing Anyon Condensation in SymTO/SymTFT
16:50 ~ 17:40 Ningfeng Wang (王宁烽) Quon classical simulation: a new way to understand quantum advantage
Dinner (A4 Hall)

Aug 27, 2025

09:30 ~ 10:20 Davide Girolami Crossing the Entanglement Frontier
Tea Break
10:50 ~ 11:40 Nan Li (李楠) Quantum coherence and basis-dependent correlations
Lunch (A4 Hall)
13:30 ~ 14:20 Changpeng Shao (邵长鹏) Quantum singular value transformation without block encodings: Near-optimal complexity with minimal ancilla
14:30 ~ 15:20 Yukai Wu (吴宇恺) Quantum simulation and quantum error correction with two-dimensional ion crystals
Tea Break
15:50 ~ 16:40 Xiaofei Qi (齐霄霏) Entanglement negativity for bipartite fermionic systems
16:50 ~ 17:40 Fuchuan Wei (魏付川) Long-range nonstabilizerness from quantum codes, orders, and correlations
Dinner (A4 Hall)

Aug 28, 2025

09:30 ~ 10:20 Ke Li (李科) From Operator Space to Quantum Rényi Information: Additivity and Operational Interpretation
Tea Break
10:50 ~ 11:40 Yinan Li (李绎楠) Rigorous QROM Security Proofs for Some Post-Quantum Signature Schemes Based on Group Actions
Lunch (A4 Hall)
13:30 ~ 14:20 N/A N/A Turaev-Viro invariant from $U_{q}sl(2; \mathbb{R})$
14:30 ~ 15:20 Qi Zhao (赵琦) Quantum entanglement accelerates quantum simulation
Tea Break
15:50 ~ 16:40 Penghui Yao (姚鹏晖) Nonlocal Games and Self-tests in the Presence of Noise
Dinner (A4 Hall)

Aug 29, 2025

09:30 ~ 10:20 Yuxiang Yang (杨宇翔) Compression of many-copy and shallow-circuit states.
Tea Break
10:50 ~ 11:40 Linghang Kong (孔令航) Louvre: Relaxing Hardware Requirements of Quantum LDPC Codes by Routing
Lunch (A4 Hall)

An Dong (安东)

Dong Chongying (董崇英)

Fang Kun (方堃)

Gao Li (高力)

Girolami Davide

Hung Ling-Yan (孔令欣)

Jing Naihuan (景乃桓)

Kong Linghang (孔令航)

Li Ke (李科)

Li Yinan (李绎楠)

Li Nan (李楠)

Liu Zhengwei (刘正伟)

Ma Xiongfeng (马雄峰)

Qi Xiaofei (齐霄霏)

Ren Li (任丽)

Shao Changpeng (邵长鹏)

Wang Ningfeng (王宁烽)

Wei Fuchuan (魏付川)

Wu Yukai (吴宇恺)

N/A (N/A)

Yang Yuxiang (杨宇翔)

Yao Penghui (姚鹏晖)

Zhao Qi (赵琦)

Zhao Zishuo (赵子烁)

Zhou You (周游)

Speaker:
Dong An (安东), Peking University
Title:
Quantum algorithms for matrix eigenvalue transformation
Abstract:
Quantum computers are expected to simulate unitary dynamics (i.e., Hamiltonian simulation) much faster than classical computers. However, most scientific computing applications involve non-unitary eigenvalue transformations. In this talk, we will discuss quantum algorithms for implementing those non-unitary eigenvalue transformations. The first algorithm is based on the Laplace transform and a recently proposed linear combination of Hamiltonian simulation formalism, and the second algorithm is based on a contour integral formalism. We will present several applications of the algorithms, including matrix inverses and solving differential equations of different forms.
Speaker:
Chongying Dong (董崇英), University of California, Santa Cruz
Title:
Symmetries beyond group actions
Abstract:
I will discuss our recent investigation into the generalized symmetries of algebras in modular tensor categories, based on a joint work with Siu-Hung NG, Li Ren and Feng Xu.
Speaker:
Kun Fang (方堃), The Chinese University of Hong Kong, Shenzhen
Title:
Generalized quantum asymptotic equipartition and its applications
Abstract:
We establish a generalized quantum asymptotic equipartition property (AEP) beyond the i.i.d. framework where the random samples are drawn from two sets of quantum states. In particular, under suitable assumptions on the sets, we prove that all operationally relevant divergences converge to the quantum relative entropy between the sets. More specifically, both the smoothed min- and max-relative entropy approach the regularized relative entropy between the sets. Notably, the asymptotic limit has explicit convergence guarantees and can be efficiently estimated through convex optimization programs, despite the regularization, provided that the sets have efficient descriptions. We give four applications of this result: (i) The generalized AEP directly implies a new generalized quantum Stein’s lemma for conducting quantum hypothesis testing between two sets of quantum states. (ii) We introduce a quantum version of adversarial hypothesis testing where the tester plays against an adversary who possesses internal quantum memory and controls the quantum device and show that the optimal error exponent is precisely characterized by a new notion of quantum channel divergence, named the minimum output channel divergence. (iii) We derive a relative entropy accumulation theorem stating that the smoothed min-relative entropy between two sequential processes of quantum channels can be lower bounded by the sum of the regularized minimum output channel divergences. (iv) We apply our generalized AEP to quantum resource theories and provide improved and efficient bounds for entanglement distillation, magic state distillation, and the entanglement cost of quantum states and channels. At a technical level, we establish new additivity and chain rule properties for the measured relative entropy which we expect will have more applications.
Speaker:
Li Gao (高力), Wuhan University
Title:
Convex Splitting: tight analysis and multipartite case
Abstract:
Convex splitting is a powerful tool in quantum information that has been used in many information-processing protocols such as quantum state redistribution and quantum channel coding. In this talk, we will present some near optimal one-shot estimates for convex splitting which yields matched second-order asymptotics as well as error and strong converse exponent. Moreover, using an interesting decomposition, our error exponent estimate also applies to multipartite case, which leads to the resolution of Quantum Broadcast Channel Simulation. This talk is based on joint works with Hao-Chung Cheng and Mario Berta.
Speaker:
Davide Girolami, Polytechnic of Turin
Title:
Crossing the Entanglement Frontier
Abstract:

In this talk, I discuss recent results on theoretically and experimentally quantifying Entanglement. In particular, newfound quantum laws dictate that classical information (the outcome of a measurement) can freely spread into the Universe, while broadcasting quantum information (the wavefunction of a system) is subject to limitations, as local Entanglement in systems of many particles is inevitably suppressed.

Refs:

Npj Quantum Information 10 (1), 60 (2024);

Physical review letters 129 (1), 010401 (2022);

Physical review letters 128 (1), 010401 (2022)

Speaker:
Ling-Yan Hung (孔令欣), Tsinghua University
Title:
A 2D-CFT Factory: Critical Lattice Models from Competing Anyon Condensation in SymTO/SymTFT
Abstract:
In this talk, we introduce a “CFT factory”: a novel algorithm of methodically generating 2D lattice models that would flow to 2D conformal fixed points in the infrared. These 2D models are realised by giving critical boundary conditions to 3D topological orders (symTOs/symTFTs) described by string-net models, often called the strange correlators. We engineer these critical boundary conditions by introducing a commensurate amount of non-commuting anyon condensates. The non-invertible symmetries preserved at the critical point can be controlled by studying a novel ``refined condensation tree’’. Our structured method generates an infinite family of critical lattice models, including the A-series minimal models, and uncovers previously unknown critical points. Notably, we find at least three novel critical points (\(c\approx1.3\), \(1.8\), and \(2.5\) respectively) preserving the Haagerup symmetries, in addition to recovering previously reported ones. The condensation tree, together with a generalised Kramers-Wannier duality, predicts precisely large swathes of phase boundaries, fixes almost completely the global phase diagram, and sieves out second order phase transitions. This is not only illustrated in well-known examples (such as the 8-vertex model related to the \(A_5\) category) but also further verified with precision numerics, using our improved (non-invertible) symmetry-preserving tensor-network RG, in novel examples involving the Haagerup symmetries. We show that critical couplings can be precisely encoded in the categorical data (Frobenius algebras and quantum dimensions in unitary fusion categories), thus establishing a powerful, systematic route to discovering and potentially classifying new conformal field theories.
Speaker:
Naihuan Jing (景乃桓), North Carolina State University
Title:
Local unitary equivalence and hypermatrix algebra
Abstract:
Entanglement is a key phenomenon in quantum theory and is invariant under local unitary (LOU) transformations. We will discuss the correspondence of LOU and simultaneous orthogonal equivalence for quantum bipartite states, and formulate a complete set of LOU invariants for tripartite states using techniques of hypermatrix algebra and Futorny-Horn-Sergeichuk’s Specht identities for quiver equivalence. We will also discuss possible generalization to multipartite quantum states.
Speaker:
Linghang Kong (孔令航), Zhongguancun Laboratory
Title:
Louvre: Relaxing Hardware Requirements of Quantum LDPC Codes by Routing
Abstract:
Generalized bicycle codes (GB codes) represent a promising family of quantum low-density parity-check codes, characterized by high encoding rates and relatively local qubit connectivity. A subclass of the GB code called bivariate bicycle codes (BB codes) has garnered significant interest due to their compatibility with two-layer connectivity architectures on superconducting quantum processors. However, one key limitation of BB codes is their high qubit connectivity degree requirements (degree 6), which exacerbates the noise susceptibility of the system. In this work, we propose Louvre, a routing-based framework for reducing qubit connectivity in GB codes. Specifically, Louvre-7 achieves degree reduction while preserving the syndrome extraction circuit depth, whereas Louvre-8 further minimizes the connectivity by slightly increasing the circuit depth. When applied to BB codes, these two schedules could reduce the average degree to 4.5 and 4, respectively. Crucially, Louvre eliminates some of the long-range, error-prone connections, which is a distinct advantage over prior approaches. Numerical simulations demonstrate that Louvre-7 has an indistinguishable logical error rate as the standard syndrome extraction circuits of GB codes, while Louvre-8 only incurs a slight error rate penalty. Though most of our analysis focuses on GB codes defined on periodic boundary conditions, we further discuss the adaptability of Louvre to open-boundary lattices and defect-containing grids, underscoring its broader applicability in practical quantum error correction architectures.
Speaker:
Ke Li (李科), Harbin Institute of Technology
Title:
From Operator Space to Quantum Rényi Information: Additivity and Operational Interpretation
Abstract:
The connection between operator theory and quantum entropies dates back to the early days of the 20th century, when von Neumann formulated the mathematical foundation of quantum mechanics. I will talk about the recent development of this connection. From the perspective of operator space theory, we discuss the definitions and properties of the sandwiched quantum Rényi divergence and its induced information quantities. In particular, we show how tools from operator space theory help us prove the additivity of quantum Rényi information, which is crucial in establishing its operational meaning.
Speaker:
Nan Li (李楠), Academy of Mathematics and Systems Science, CAS
Title:
Quantum coherence and basis-dependent correlations
Abstract:
Since both coherence and quantum correlations arise from the superposition principle and can be regarded as resources in quantum information tasks, it is of significance to investigate the interplay between them from different perspectives. In this work we focus on the basis-dependent correlations in a bipartite state defined by the coherence difference between global state and local state relative to a local basis and characterize bipartite states with vanishing basis-dependent correlations. Using the relative entropy of coherence, the structure of such states has been determined by Yadin et al. [Phys. Rev. X 6, 041028 (2016)], which we call block-diagonal product states here. We demonstrate that the set of block-diagonal product states can also be characterized by the property of possessing vanishing basis-dependent correlations using the coherence measure based on quantum Fisher information. In this sense, bipartite states with vanishing basis-dependent correlations can be characterized by the property of possessing no correlations contributing to the enhancement of parameter estimation precision, and thus are of metrological meanings. As a by-product of this result, we describe the structure of quantum ensembles saturating the convexity inequality in the resource theory of coherence using the coherence measure based on quantum Fisher information, which may be of independent interest.
Speaker:
Yinan Li (李绎楠), Wuhan University
Title:
Rigorous QROM Security Proofs for Some Post-Quantum Signature Schemes Based on Group Actions
Abstract:

Group action based cryptography was formally proposed in the seminal paper of Brassard and Yung (Crypto ’90) and recently further developed by Ji et al. (TCC ’19) and Alamati et al. (AsiaCrypt ’19). Based on a one-way group action, Three submissions to the NIST’s call for additional post-quantum digital signatures, such as ALTEQ and MEDS. These schemes can be shown to be secure in the quantum random oracle model (QROM) modulo certain assumptions on the group actions, thanks to the progress on the QROM security of the Fiat–Shamir transformation (Liu–Zhandry and Don et al., Crypto ’19). One approach to proving the QROM security for such group action based schemes uses the perfect unique response property introduced by Unruh (Eurocrypt ’12; AsiaCrypt ’17). In the contexts of ALTEQ and MEDS, this means that a random element does not have a non-trivial automorphism. Before this work, only computational evidence for small dimensions (Bläser et al., PQCrypto ’24; Reijnders–Samardjiska–Trimoska, Des. Codes Cryptogr. ’24) or subexponential bounds (Li–Qiao, FOCS ’17) are known.

In this work, we formally prove that the average order of stabilizer groups is asymptotically trivial. As a result, when the dimension is large enough, all but an exponentially small fraction of alternating trilinear forms or matrix codes have the trivial stabilizer, confirming the assumptions for alternating trilinear forms (ALTEQ) and matrix codes (MEDS). Our approach is to examine the fixed points of the induced action of an invertible matrix over a finite field on trilinear forms.

Speaker:
Zhengwei Liu (刘正伟), Tsinghua University
Title:
Construct Planar Algebras by Classical and Quantum Computers
Abstract:
We propose a new program to effectively construct planar algebras and tensor categories by classical and quantum computer. Several brand new examples are discovered.
Speaker:
Xiongfeng Ma (马雄峰), Tsinghua University
Title:
Measurement-Assisted Quantum Circuits: Circuit Complexity and Entanglement Generation
Abstract:

Measurement-assisted quantum circuits offer a powerful approach to quantum computing by “trading measurement and space for circuit depth,” a key advantage for mitigating noise in shallow architectures. Yet, their resource requirements and fundamental limits has remained elusive, hindering systematic optimization. This talk introduces a unified embedded complexity framework to characterize such circuits. We prove that for states generated by general measurement-assisted circuits, embedded complexity is lower-bounded by circuit volume, extending the linear growth theorem and showing that intermediate measurements and ancillas cannot drastically reduce the cost of generic state preparation. This delineates the intrinsic limits of measurement-assisted protocols and informs applications such as random circuit sampling and quantum shadow tomography. For specific targets, we present a variational optimization scheme using parameterized measurements and efficient gradient estimation to avoid “barren plateaus,” enabling high-fidelity preparation of long-range entangled states at shallow depths and outperforming conventional circuits. These results map the capability boundaries and implementation pathways of measurement-assisted circuits, providing new foundations for fault-tolerant quantum computing and resource optimization. This work is published in [PRL 134, 170601 (2025); arXiv:2408.16602].

Bio: Xiongfeng Ma is a professor at the Institute for Interdisciplinary Information Sciences, Tsinghua University. He is a Fellow of the American Physical Society (APS), and a Fellow of Optica. He received his Bachelor of Science degree from Peking University in 2003 and his Ph.D. from the University of Toronto in 2008. His main research direction is quantum information science, including quantum cryptography, quantum computing, and quantum foundational theories.

Speaker:
N/A N/A, N/A
Title:
Turaev-Viro invariant from \(U_{q}sl(2; \mathbb{R})\)
Abstract:
We define a family of Turaev-Viro type invariants of hyperbolic 3-manifolds with totally geodesic boundary from the 6j-symbols of the modular double of \(U_{q}sl(2; \mathbb{R})\), and prove that these invariants decay exponentially with the rate the hyperbolic volume of the manifolds and with the 1-loop term the adjoint twisted Reidemeister torsion of the double of the manifolds. This is a joint work with Tianyue Liu, Shuang Ming, Xin Sun and Baojun Wu.
Speaker:
Xiaofei Qi (齐霄霏), Shanxi University
Title:
Entanglement negativity for bipartite fermionic systems
Abstract:
Quantum entanglement plays a fundamental and important role in quantum information theory. In this talk, we discuss the behavior of physical positive linear maps in fermionic systems, and then propose the phase partial transpose and the phase entanglement negativity. We prove that the phase entanglement negativity is an entanglement monotone.
Speaker:
Li Ren (任丽), Sichuan University
Title:
Reverse categories and reconstruction program
Abstract:
The reconstruction program posits that every modular category can be realized as a module category of a rational vertex operator algebra. In category theory, each modular category has an associated reverse category. In this talk, I will explore how to realize the reverse of a modular category through the framework of vertex operator algebras.
Speaker:
Changpeng Shao (邵长鹏), Academy of Mathematics and Systems Science, CAS
Title:
Quantum singular value transformation without block encodings: Near-optimal complexity with minimal ancilla
Abstract:

We develop new algorithms for Quantum Singular Value Transformation (QSVT), a unifying framework that encapsulates most known quantum algorithms and serves as the foundation for new ones. Existing implementations of QSVT rely on block encoding, incurring an intrinsic \(O(\log L)\) ancilla overhead and circuit depth \(\widetilde{O}(L d\lambda )\) for polynomial transformations of a Hamiltonian \(H=\sum_{k=1}^L H_k\), where \(d\) is the polynomial degree and \(\lambda=\sum_{k}\|H_k\|\).

We introduce a simple yet powerful approach that utilizes only basic Hamiltonian simulation techniques, namely, Trotter methods, to: (i) eliminate the need for block encoding, (ii) reduce the ancilla overhead to only a single qubit, and (iii) still maintain near-optimal complexity. Our method achieves a circuit depth of \(\widetilde{O}(L(d\lambda_{\mathrm{comm}})^{1+o(1)})\), without requiring any complicated multi-qubit controlled gates. Moreover, \(\lambda_{\mathrm{comm}}\) depends on the nested commutators of the terms of \(H\) and can be substantially smaller than \(\lambda\) for many physically relevant Hamiltonians, a feature absent in standard QSVT. To achieve these results, we make use of Richardson extrapolation in a novel way, systematically eliminating errors in any interleaved sequence of arbitrary unitaries and Hamiltonian evolution operators, thereby establishing a general framework that encompasses QSVT but is more broadly applicable.

As applications, we develop end-to-end quantum algorithms for solving linear systems and estimating ground state properties of Hamiltonians, both achieving near-optimal complexity without relying on oracular access. Overall, our results establish a new framework for quantum algorithms, significantly reducing hardware overhead while maintaining near-optimal performance, with implications for both near-term and fault-tolerant quantum computing.

Speaker:
Ningfeng Wang (王宁烽), Tsinghua University
Title:
Quon classical simulation: a new way to understand quantum advantage
Abstract:
We establish Quon Classical Simulation (QCS), answering a long standing open question on unifying efficient classical simulations of both Clifford and Matchgates quantum circuits. QCS unifies various methods on classical simulations of hybrid-Clifford-Matchgate quantum circuits and tensor networks, based on the 3D Quon picture language which is a topological quantum field theory. It provides new insights to explore quantum advantage. This is joint work with Zixuan Feng, Zhengwei Liu and Fan Lu. https://arxiv.org/abs/2505.07804v2
Speaker:
Fuchuan Wei (魏付川), Tsinghua University
Title:
Long-range nonstabilizerness from quantum codes, orders, and correlations
Abstract:
We investigate long-range magic (LRM), defined as nonstabilizerness that cannot be (approximately) erased by shallow local unitary circuits. In doing so, we prove a robust generalization of the Bravyi-König theorem. By establishing connections to the theory of fault-tolerant logical gates on quantum error-correcting codes, we show that certain families of topological stabilizer code states exhibit LRM. Then, we show that all ground states of topological orders that cannot be realized by topological stabilizer codes, such as Fibonacci topological order, exhibit LRM, which yields a “no lowest-energy trivial magic” result. Building on our considerations of LRM, we discuss the classicality of short-range magic from e.g. preparation and learning perspectives, and put forward a “no low-energy trivial magic” (NLTM) conjecture that has key motivation in the quantum PCP context. Our study leverages and sheds new light on the interplay between quantum resources, error correction and fault tolerance, complexity theory, and many-body physics.
Speaker:
Yukai Wu (吴宇恺), Tsinghua University
Title:
Quantum simulation and quantum error correction with two-dimensional ion crystals
Abstract:
Ion trap is one of the leading physical platforms for quantum information processing, with long coherence time, high quantum-gate fidelity, and long-range qubit connectivity. Recently, two-dimensional (2D) ion crystals have become a promising approach to scale up the ionic qubit number. In this talk, I will introduce our recent progress on quantum simulation and quantum error correction with 2D ion crystals. To utilize the phonon-mediated long-range interaction between the ions for quantitative quantum simulation tasks, we develop an efficient and precise scheme to learn the all-to-all-connected Ising model Hamiltonian through the experimentally available global laser and microwave manipulation together with single-shot measurement of the ions, and demonstrate this scheme for up to 300 ionic qubits. As for quantum error correction, we analyze the effect of crosstalk errors between parallel entangling gates due to this long-range interaction, and optimize the parallelism level to balance the crosstalk error and the idling error during the execution of the gates. We further examine the spatial dependence of the crosstalk error, and show that a logical error rate below \(10^{-10}\) can be achieved in different parameter regimes by increasing the code distance.
Speaker:
Yuxiang Yang (杨宇翔), The University of Hong Kong
Title:
Compression of many-copy and shallow-circuit states.
Abstract:
Shallow quantum circuits feature not only computational advantage over their classical counterparts but also cutting-edge applications. Storing quantum information generated by shallow circuits is a fundamental question of both theoretical and practical importance that remained largely unexplored. In this work, we show that \(N\) copies of an unknown \(n\)-qubit state generated by a fixed-depth circuit can be compressed into a hybrid memory of \(O(n \log N)\) (qu)bits, which achieves the optimal scaling of memory cost. Our work shows that the computational complexity of resources can significantly impact the rate of quantum information processing, offering a unique and unified view of quantum Shannon theory and quantum computing in the NISQ era. Based on: Phys. Rev. Lett. 134, 010603 (2025; https://arxiv.org/abs/2404.11177)
Speaker:
Penghui Yao (姚鹏晖), Nanjing University
Title:
Nonlocal Games and Self-tests in the Presence of Noise
Abstract:

Self-tests are a fundamental class of nonlocal games, which allow one to uniquely determine the underlying quantum state and measurement operators used by the players, based solely on their observed input-output correlations. Motivated by the limitations of current quantum devices, we study self-testing in the high-noise regime, where the two players are restricted to sharing many copies of a noisy entangled state with an arbitrary constant noise rate. In this setting, many existing self-tests fail to certify any nontrivial structure. We first characterize the maximal winning probabilities of the CHSH game, the Magic Square game, and the 2-out-of-\(n\) CHSH game as functions of the noise rate, under the assumption that players use traceless binary observables. These results enable the construction of device-independent protocols for estimating the noise rate. Building on this analysis, we show that these three games—together with an additional test enforcing the tracelessness of binary observables—can self-test one, two, and \(n\) pairs of anticommuting Pauli operators, respectively. These are the first known self-tests that are robust in the high-noise regime and remain sound even when the players’ measurements are noisy. Our proofs rely on Sum-of-Squares (SoS) decompositions and Pauli analysis techniques developed in the contexts of quantum proof systems and quantum learning theory.

This is a joint work with Honghao Fu, Minglong Qin and Haochen Xu.

Speaker:
Zishuo Zhao (赵子烁), Tsinghua University
Title:
Bimodule Markov semigroups
Abstract:
This talk introduces bimodule quantum Markov semigroups, which describe the dynamics of symmetric quantum systems within the framework of quantum Fourier analysis. The symmetry is mathematically encoded by a finite index inclusion of von Neumann algebras. We generalize the classical notions of equilibrium and detailed balance, revealing new structures. When this condition is met, the fixed points of the channel form a von Neumann subalgebra. Furthermore, we demonstrate that the evolution of densities under these semigroups acts as a gradient flow for relative entropy with respect to a “hidden density” derived from the system’s underlying symmetries. This perspective allows for the establishment of several key functional inequalities in the bimodule setting, including the Poincaré, logarithmic Sobolev, and Talagrand inequalities.
Speaker:
Qi Zhao (赵琦), The University of Hong Kong
Title:
Quantum entanglement accelerates quantum simulation
Abstract:

Quantum entanglement is an essential feature of many-body systems that impacts both quantum information processing and fundamental physics. The growth of entanglement is a major challenge for classical simulation methods. In our recent work [Nature Physics 25, QIP 2025], we investigate the relationship between quantum entanglement and quantum simulation, showing that product-formula approximations can perform better for entangled systems, tending to the average-performance [PRL 129 (27), 270502, QIP22 talk]. We establish a tighter upper bound for algorithmic error in terms of entanglement entropy and develop an adaptive simulation algorithm incorporating measurement gadgets to estimate the algorithmic error. This shows that entanglement is not only an obstacle to classical simulation, but also a feature that can accelerate quantum simulation algorithms.

Bio: Prof. Qi Zhao is an Assistant Professor in the Department of Computer Science, the University of Hongkong (HKU). In 2024, he was recognized as one of the MIT Technology Review “Innovators Under 35” for the Asia Pacific Region. His research interests include quantum simulation, quantum computing, quantum information, and entanglement detection. He obtained a Bachelor’s and Doctoral degree from Tsinghua University in 2014 and 2018 respectively. He was a postdoctoral researcher at the University of Science and Technology of China in 2019. He was a Hartree Postdoctoral Fellow at the University of Maryland in the United States before joining HKU as Assistant Professor in 2022. He has published 46 journal articles, including Nature, Nature Physics, PRL, PRX, npj Quantum Information, PNAS, and IEEE TIT. His works have also been presented as contributed talks at important conferences in quantum information theory, such as QIP, AQIS, TQC, and QCrypt.

Speaker:
You Zhou (周游), Fudan University
Title:
Robust and efficient estimation of global quantum properties under realistic noise
Abstract:
Measuring global quantum properties—such as the fidelity to complex multipartite states—is both an essential and experimentally challenging task. Classical shadow estimation offers favorable sample complexity, but typically relies on many-qubit circuits that are difficult to realize on current platforms. We propose the robust phase shadow scheme, a measurement framework based on random circuits with controlled-\(Z\) as the unique entangling gate type, tailored to architectures such as trapped ions and neutral atoms. Leveraging tensor diagrammatic reasoning, we rigorously analyze the induced circuit ensemble and show that phase shadows match the performance of full Clifford-based ones. Importantly, our approach supports a noise-robust extension via purely classical post-processing, enabling reliable estimation under realistic, gate-dependent noise where existing techniques often fail. Additionally, by exploiting structural properties of random stabilizer states, we design an efficient post-processing algorithm that resolves a key computational bottleneck in previous shadow protocols. Our results enhance the practicality of shadow-based techniques, providing a robust and scalable route for estimating global properties in noisy quantum systems. (arxiv: 2507.13237)