Adaptive low-rank variational quantum algorithm for simulating dissipative dynamics in photosynthetic complexes.
Atiye Zeynali1, Zahra Bakhshi2
1Department of Physics, Faculty of Basic Sciences, Shahed University, Tehran, Iran.
Scientific Reports
|July 11, 2026
Summary
We developed a quantum algorithm (LR-VQA) for simulating complex molecular systems, overcoming classical limitations. This quantum biology tool achieves high accuracy and efficiency for large systems.
Area of Science:
- Quantum Biology
- Computational Chemistry
- Quantum Information Science
Background:
- Simulating open quantum systems is crucial for understanding energy transfer in biological processes like photosynthesis.
- Exact density-matrix propagation methods face exponential complexity, limiting simulations to small systems (approx. 15 chromophores).
- Existing specialized methods (HOPS, Meso-HOPS, multi-Davydov) offer tractability only in specific regimes.
Purpose of the Study:
- To develop a quantum algorithm with polynomial scaling for simulating large open quantum systems.
- To provide a quantum-hardware-compatible framework that complements classical simulation techniques.
- To enable quantum advantage in quantum biology by simulating systems with 50-300 chromophores.
Main Methods:
- Developed an adaptive low-rank variational quantum algorithm (LR-VQA).
- Employed singular value decomposition-based tensor compression for polynomial scaling.
- Utilized dissipation-engineered cost functions for enhanced efficiency.
- Benchmarked on Fenna-Matthews-Olson (FMO) complexes (5-12 chromophores).
- Simulated performance on Noisy Intermediate-Scale Quantum (NISQ) devices using IBM Heron noise models.
Main Results:
- Achieved polynomial scaling [Formula: see text] with LR-VQA, contrasting with exponential scaling of exact methods.
- Demonstrated high mean fidelities (0.87-0.95) on FMO complexes across 50 trials.
- Validated NISQ device viability with a fidelity of [Formula: see text] for a 7-site complex.
- Identified a computational crossover at [Formula: see text] chromophores, beyond which LR-VQA is the only tractable quantum-compatible pathway.
- Achieved agreement with experimental energy transfer timescales within 3% accuracy.
- Open-source implementation runs in under 90 seconds.
Conclusions:
- LR-VQA offers a scalable and accurate quantum-hardware-compatible method for simulating open quantum systems.
- The framework paves the way for quantum advantage in quantum biology, particularly for photosynthetic antenna systems.
- Future extensions include non-Markovian dynamics and simulating significantly larger systems (50-300 chromophores).
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