Marco Cerezo - Group Fourier Decompositions as Fingerprints of Quantum Resources—and a Path Beyond Unitary Free Operations
In this talk we present a framework for studying resourcefulness in quantum resource theories (QRTs) whose free operations are generated by a unitary representation of a group. Our central tool is the Group Fourier decomposition (GFD)—the projection of a state onto irreducible representations—whose component norms provide compact “fingerprints” that certify and stratify resourcefulness, yielding witnesses across entanglement, coherence, stabilizer-ness, fermionic Gaussianity, and more. We close by showing how unitary free operations in Lie-algebraic QRTs can be promoted to resource-nonincreasing channels that provably map free states to free states. This extends the Local Unitary→SLOCC transition in entanglement and yields new free operations in QRTs such as that of fermionic Gaussianity.
Daniel Stilck-França - Scalable learning and certification of local time dependent quantum dynamics and noise
Learning and certifying time-dependent quantum dynamics under realistic noise is key to trustworthy quantum simulation. I will present an efficient protocol that reconstructs the generators Hamiltonian and Markovian noise generators of multi-qubit devices from derivatives of expectation values of few-qubit observables via stable polynomial interpolation and semidefinite programming. To the best of our knowledge, this is the first scheme to efficiently learn local time-dependent Hamiltonians and Markovian noise at scale. The scheme is experimentally light, requiring only product-state preparation, single-qubit measurements, and post-processing polynomial in the qubit number, while the number of samples needed to identify all parameters grows only logarithmically with the qubit count. Our protocol thus enables a-posteriori certification of various crucial routines on quantum simulators such as adiabatic state preparation, and yield confidence guarantees for estimated expectation values along the schedule. Thus, together, these results provide a scalable route to diagnosing and certifying controlled time-dependent many-body dynamics. If time permits, we will also discuss recent experimental implementations of related protocols.
Jacopo De Nardis - Computing More with Less: Random Tensor Networks and New Algorithms for Time Evolution
I will present recent analytical and numerical results on quantum complexity and anticoncentration in many-body wave functions, using random tensor-network ensembles as a powerful, tractable testbed for non-equilibrium dynamics. I will then introduce new algorithms for the classical simulation of quantum time evolution: (i) hybrid tensor-network methods enhanced by Clifford unitaries, and (ii) Monte Carlo sampling of spatially contracted networks. Together, these approaches extend the reach of tensor network simulations, showing how less resources suffice to capture key quantum features.
J. Ignacio Cirac - Efficient Preparation of Many-Body Quantum States
Tensor Network States, like matrix product or projected entangled pair states play an important role in both, quantum information theory and many-body physics. They offer a compact and efficient representation, enabling accelerated numerical computations and providing intuitive insights into many-body phenomena. In this talk, I will discuss how certain states can be efficiently prepared and manipulated using quantum devices, highlighting the use of local operations and classical communication.
Immanuel Bloch - Quantum Simulation and Quantum Computing with Fermions
Quantum simulation has emerged as an interdisciplinary research field that enables microscopic access to quantum matter, both in and out of equilibrium, across various physical platforms. As an example, we analyze the emergence of the pseudogap phase in the fermionic Hubbard model. We identify a universal behavior of magnetic correlations upon entering the pseudogap phase, observed in both spin-spin and higher-order spin-charge correlations.
In addition to analog approaches, gate-based fermionic quantum computing offers distinct advantages for quantum simulations. We demonstrate the elementary operations required to manipulate orbital degrees of freedom, which form the basis of a fermionic quantum computer. We show high-fidelity gate operations and the generation of long-lived entangled states. Such gate-based operations can also be used to read out relevant order parameters and pairing correlations in analog quantum simulations.
Nathan Goldman - Elucidating topological quantum matter with a thermodynamic relation
In 1982, Streda and Widom established a thermodynamic relation that connects the quantized Hall conductivity of insulating phases to the magnetic response of particle density. This presentation examines how this fundamental relation can be harnessed and generalized to shed light on key properties of topological quantum matter, with particular emphasis on strongly correlated phases and out-of-equilibrium settings.
Barbara Kraus - Quantum algorithm for cooling
We propose a cooling algorithm, which can be utilized for state preparation. We analyze its properties in noiseless and noisy settings and show that in various scenarios the cooling algorithm outperforms the dissipative state preparation method.
Jose Ignacio Latorre - TBC
Enrique Rico - Real-Time Dynamics in a (2+1)-D Gauge Theory: The Stringy Nature on a Superconducting Quantum Simulator
Understanding the confinement mechanism in gauge theories and the universality of effective string-like descriptions of gauge flux tubes remains a fundamental challenge in modern physics. We probe string modes of motion with dynamical matter in a digital quantum simulation of a (2+1) dimensional gauge theory using a superconducting quantum processor with up to 144 qubits, stretching the hardware capabilities with quantum-circuit depths comprising up to 192 two-qubit layers. We realize the Z2-Higgs model (Z2HM) through an optimized embedding into a heavy-hex superconducting qubit architecture, directly mapping matter and gauge fields to vertex and link superconducting qubits, respectively. Using the structure of local gauge symmetries, we implement a comprehensive suite of error suppression, mitigation, and correction strategies to enable real-time observation and manipulation of electric strings connecting dynamical charges. Our results resolve a dynamical hierarchy of longitudinal oscillations and transverse bending at the end points of the string, which are precursors to hadronization and rotational spectra of mesons. We further explore multi-string processes, observing the fragmentation and recombination of strings. The experimental design supports 300,000 measurement shots per circuit, totaling 600,000 shots per time step, enabling high-fidelity statistics. We employ extensive tensor network simulations using the basis update and Galerkin method to predict large-scale real-time dynamics and validate our error-aware protocols. This work establishes a milestone for probing non-perturbative gauge dynamics via superconducting quantum simulation and elucidates the real-time behavior of confining strings.
Mari Carmen Bañuls - Approximating Low-temperature Gibbs states with tensor networks
TNS provide efficient approximations of thermal equilibrium states. The most common algorithm constructs a purification of the thermal state starting from infinite temperature and evolving the state in imaginary time towards lower temperature. At very low temperatures, this has the practical drawback of trying to approximate a low rank density operator via a full rank one. We present a complementary ansatz, constructed from the zero-temperature limit, the ground state, which can be found with a standard tensor network approach. Motivated by properties of the ground state for conformal field theories, our ansatz is especially well-suited near criticality. Moreover, it allows an efficient computation of thermodynamic quantities and entanglement properties. We demonstrate the performance of our approach with a tree tensor network ansatz, although it can be extended to other tensor networks, and present results illustrating its effectiveness in capturing the finite-temperature properties in one- and two-dimensional scenarios. In particular, in the critical 1D case we show how the ansatz reproduces the finite temperature scaling of entanglement in a CFT.
Rahul Trivedi - Many-body open systems beyond the Markov approximation
Open system dynamics, in continuous time, remains largely understood within the Born-Markov approximation where a closed form master equation can be obtained to describe the system dynamics. However, many-body systems arising in quantum optics and condensed matter physics often interact with environments that have memory and cannot be described by a Lindblad master equation. While both theoretical and algorithmic tools are available for understanding many-body Markovian open systems, their counterparts for non-Markovian systems remain less well understood.
Miguel Ángel Martín-Delgado - Quantum Technologies with Topological Color Codes
Topology is one of the latest branches in the history of mathematics and has entered fully into the most modern aspects of theoretical physics: quantum computation. This talk presents an overview of topological color codes as a solution for fault-tolerant quantum computing. Topology helps address the fundamental challenge of quantum computation: overcoming its inherent fragility to harness its enormous potential. After demonstrating the experimental realization of color codes across three quantum computing platforms—trapped ions with high-fidelity operations, cold atoms offering scalable architectures, and superconducting circuits providing fast gate times—we address the remaining challenges toward realizing fault-tolerant quantum computers capable of executing practical quantum algorithms.
Federica Surace - Metastability in quantum many-body systems
Metastability —the persistence of a system in a long-lived, non-equilibrium state— is a ubiquitous phenomenon in physics, underlying behaviors from supercooled liquids, glasses, and magnetic materials to the false vacuum in cosmology. In this talk, I will explore how metastability arises in quantum many-body dynamics. I will present rigorous results on the lifetimes of metastable states in quantum many-body systems and discuss how these effects can be probed and controlled in state-of-the-art quantum simulators.
Michal Oszmaniec - TBC
Garnet Chan - TBC
Ángela Capel - TBC
Martin Kliesch - General, efficient, and robust Hamiltonian engineering
Implementing the time evolution under a desired target Hamiltonian is critical for various applications in quantum science. Due to the exponential increase of parameters in the system size and due to experimental imperfections, this task can be challenging in quantum many-body settings.
Leticia Tarruell - TBC
Juan José García-Ripoll - Non-local quantum many-body systems
In this talk I will present some of our attempts to develop a mathematically rigorous theory of non-Markovian open quantum systems with Gaussian environments. I will show that, for a broad class of environments which strictly generalize the Markovian environment, a system-environment unitary group can be rigorously defined and, in many cases, can also be shown to be strongly-continuous two-parameter group. I will then go onto consider many-body lattice models with non-Markovian environment and establish a Lieb-Robinson bounds for these models. Finally, I will describe our recent work on developing quantum algorithms for simulating the dynamics of these models with near-optimal scaling on the system size and evolution time.
