HQS releases Electron Spectroscopy Use Cases

Quantum simulation is rapidly reshaping electron spectroscopy. By mapping complex many-body problems onto compact quantum models, researchers can estimate excitation energies and singlet–triplet gaps using smaller circuit footprints, bringing previously computationally challenging observables within the reach of today's and tomorrow's quantum hardware.

HQS Quantum Simulations is making new Electron Spectroscopy use cases available on the HQS Cloud together with a complimentary 6‑month license of the HQStage module HQS Quantum Solver for evaluation.

What’s in the release

• Ready‑to‑run Hamiltonians for cyclopentadiene, pyrrole, and thiophene, packaged for immediate experimentation with the HQS Quantum Solver.

• Purpose‑built, hardware‑friendly models: instead of full four‑index quantum‑chemistry Hamiltonians, we provide accurate approximate Hamiltonians that retain a tiny active space around the frontier orbitals and fold remaining electron–hole excitations into a structured bath. This construction captures dynamical correlation and represents the environment via bosonic degrees of freedom (or equivalent two‑level systems), enabling the use of spin–boson style algorithms with very small circuit depths.

• Spectroscopy‑ready targets: the singlet–triplet energy gap—governing absorption onsets, triplet yields, and phosphorescence risks—is exposed as a primary benchmark. You can explore singlet–triplet splitting on HQStage and validate against trusted reference values.

Relevant links and how to get started

• GitHub: find a curated overview of the Electron Spectroscopy use cases with all relevant links and downloads: github.com/HQSquantumsimulations/hqstage-examples

• Free 6‑month license: create an account on the HQS Cloud to activate your evaluation license of the HQS Quantum Solver: cloud.quantumsimulations.de/

• YouTube: short tutorials and product insights will roll out on our channel—subscribe, stay tuned, and join the discussion: www.youtube.com/@hqsquantumsimulations

• Directly look at the HQStage documentation
  docs.cloud.quantumsimulations.de/introduction.html

• Or have a look at the Quantum Solver
  docs.cloud.quantumsimulations.de/hqs-quantum-solvers/index.html

Free Webinar: Quantum Simulation Use Case - Electron Spectroscopy

Date & Time: December 2, 2025 at 4:30 p.m. CET.
Register now

• Dr. Dmitry Golubev will discuss representing molecular Hamiltonians in terms of qubits—an essential step for quantum computing workflows.

• Dr. Hannah Rittich will present the HQS Quantum Solver and walk through practical workflows. 

Advantages of quantum simulation in electron spectroscopy

• Smaller circuits, faster iteration: the structured‑bath approach brings excited‑state calculations into reach on near‑term devices.

• Direct spectroscopy proxies: focusing on the singlet–triplet gap provides actionable insights for absorption and emission behavior.

• Open benchmarks: the HQStage release encourages reproducibility and community feedback as we broaden the molecular set and spectroscopic targets.

What’s next

A full paper detailing the methodology, approximations, and validation is forthcoming. In the meantime, we invite you to test the Electron Spectroscopy use cases on HQStage, share your results, and help us shape the roadmap.

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