Research track · Chemistry & materials
Molecular & materials research
Explore variational methods against classical chemistry baselines.
Why this horizon. Resource estimates for industrially relevant molecules (e.g. the FeMoco cofactor) call for error-corrected machines; small molecules like H₂ remain easy for classical methods.
- The problem
- Accurate electronic-structure calculations scale poorly on classical machines for some systems.
- Why quantum or hybrid methods may be relevant
- Quantum simulation of quantum systems is a long-studied candidate application.
- Classical baseline
- Established classical methods (e.g. DFT, coupled cluster) for the same molecules.
- What QAISS could provide
- VQE-style templates, simulator runs, and side-by-side baseline reports.
- What evidence would count as success
- Energies within chemical accuracy of trusted references, with cost and runtime reported.
- Limitations & open questions
- Current hardware noise and scale limit practical system size. No medical or commercial benefit is claimed.
- Current status
- Planned No experiments have been published for this track yet.
Workflow on QAISS
From question to checkable result.
- STEP 1
Write the molecular Hamiltonian in a basis set and map it to qubits.
- STEP 2
Choose an ansatz and estimate the energy from measurements (VQE).
- STEP 3
Compare with the exact or best classical answer (diagonalisation, coupled cluster).
- STEP 4
Record the passport: Hamiltonian, ansatz, shots, optimiser, seed.
Interactive · runs in your browser
Find the H₂ ground state with VQE
- Estimated energy
- —
- Error vs exact
- —
- Step
- 0
Chemical accuracy is about 1.6 mHa (1 kcal/mol). Fewer shots mean noisier estimates and a wobbling optimiser — the cost that real hardware pays on every step.
Circuit: X on q₀ · RY(θ) on q₁ · CNOT q₁→q₀, giving cos(θ/2)|10⟩ + sin(θ/2)|01⟩. Hamiltonian: H₂ in STO-3G at 0.735 Å, parity mapping, two qubits (the standard tutorial instance). The gradient uses the parameter-shift rule. Classical simulation in your browser; a 2-qubit molecule is trivial for a classical computer, which is exactly why it is a good test.
Sources
Read the literature.
- A variational eigenvalue solver on a photonic quantum processorA. Peruzzo, J. McClean, P. Shadbolt et al. · Nature Communications 5, 4213 · 2014
- Hardware-efficient variational quantum eigensolver for small molecules and quantum magnetsA. Kandala, A. Mezzacapo, K. Temme et al. · Nature 549, 242 · 2017
- Elucidating reaction mechanisms on quantum computersM. Reiher, N. Wiebe, K. M. Svore et al. · PNAS 114, 7555–7560 · 2017
- Even more efficient quantum computations of chemistry through tensor hypercontractionJ. Lee, D. W. Berry, C. Gidney et al. · PRX Quantum 2, 030305 · 2021
Cited for context. QAISS is not affiliated with the authors or publishers.
No quantum advantage, production savings, medical benefit, financial return, or security guarantee is claimed for this track.