A Deep Dive Into Sample-Based Quantum Diagonalization Methods: Javier Robledo Moreno | QGSS 2025

A Deep Dive Into Sample-Based Quantum Diagonalization Methods: Javier Robledo Moreno | QGSS 2025

🎙 Javier Robledo Moreno 👥 203K 📅 August 29, 2025 ⏱ 45 min 👁 2K 📄 lecture 🧭 2026-08-17
Available in: English (current) Français

Keywords

sample-based quantum diagonalizationquantum centric supercomputingconfiguration recoveryKrylov basisquantum chemistry

Summary

Javier Robledo Moreno, a research scientist at IBM Quantum, presents a comprehensive lecture on Sample-Based Quantum Diagonalization (SQD) and Sample-Based Krylov Quantum Diagonalization (SKQD). The talk begins by framing the problem of finding ground states of many-body Hamiltonians, which are exponentially large but sparse. SQD is introduced as a hybrid quantum-classical algorithm that uses a quantum circuit to sample relevant electronic configurations, which are then used to project and diagonalize the Hamiltonian in a reduced subspace. A key component is self-consistent configuration recovery, which mitigates noise by probabilistically correcting bit strings based on average orbital occupancies. Numerical experiments on nitrogen dissociation demonstrate that configuration recovery significantly improves accuracy, requiring only 2% signal to reach 10 millihartree error compared to 20% without recovery. The lecture then discusses circuit choices: the local unitary cluster Jastrow (LUCJ) ansatz for physically motivated circuits, and time-evolution circuits for SKQD, which offer provable convergence guarantees under certain conditions. Applications are presented, including nitrogen dissociation (58 qubits) and iron-sulfur clusters (45 and 77 qubits), with energy variance analysis showing good agreement with classical methods like DMRG. The talk emphasizes the quantum-centric supercomputing paradigm, where quantum and classical resources collaborate.

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Critical Evaluation

Value of the Information & Strength of the Argument

The lecture provides valuable insights into a cutting-edge quantum algorithm, explaining both the theoretical foundations and practical implementation details. The argumentation is solid, with clear motivations for each design choice and numerical evidence supporting the effectiveness of configuration recovery. The presentation of convergence guarantees for SKQD is particularly strong, as it addresses a key limitation of variational methods. The speaker effectively communicates complex concepts, making the material accessible to a technically proficient audience.

Scientific Rigor, Source Quality, Title Accuracy

The scientific rigor is high, with the speaker being a recognized researcher in the field. The content is consistent with published literature on SQD and SKQD, though no specific references are cited in the lecture. The title accurately reflects the content, which is a detailed technical exposition. The lecture is part of the Qiskit Global Summer School, indicating a level of institutional credibility. No comments were provided for analysis.

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Title / Content Match

The title accurately reflects the content, which is a deep dive into sample-based quantum diagonalization methods.

Quality & Reliability

8/10

The lecture is presented by a research scientist at IBM Quantum, providing a detailed and technically accurate overview of sample-based quantum diagonalization methods. The content is well-structured, includes numerical experiments and references to real applications, and is consistent with known quantum computing literature. However, it is a single lecture without external citations or peer review, and some claims are presented without extensive justification.

Key Moments

Cited Sources

  • Sample-based quantum diagonalization — Mentioned as the main algorithm discussed
  • Sample-based Krylov quantum diagonalization — Mentioned as a variant using Krylov basis
  • Local unitary cluster Jastrow ansatz — Mentioned as a physically motivated circuit

Concurring Sources

  • Sample-based quantum diagonalization — The algorithm is consistent with published research by IBM Quantum.

Contribution & Novelties

The lecture provides a clear and detailed exposition of sample-based quantum diagonalization methods, highlighting their potential for quantum-centric supercomputing. The self-consistent configuration recovery technique is a novel contribution that significantly improves noise resilience. The presentation of convergence guarantees for SKQD adds theoretical depth. The applications to iron-sulfur clusters demonstrate practical relevance.

Pour aller plus loin :

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Radar Profile

The radar profile shows high scores in technical level and information quality, indicating a technically dense and reliable lecture. The lower scores in quantity of information and global reliability reflect the lack of external citations and the single-source nature of the content.

Reliability 8/10