A Biomimetic Quantum Computing Approach to Simulating Exciton Energy Transfer in the Fenna-Matthews-Olson Complex

Abstract

Background: The near-unity quantum efficiency of energy transfer within the Fenna-Matthews-Olson (FMO) pigment-protein complex remains a benchmark for photosynthetic light harvesting. Simulating these non-Markovian dynamics classically requires solving hierarchical equations of motion (HEOM), which is computationally expensive due to the exponential scaling of the system's Hilbert space.

Methods: To provide a highly scalable methodological alternative, the tight-binding Hamiltonian of the seven-site FMO complex was mapped onto a parameterized 3-qubit digital quantum circuit. Using a Trotter-Suzuki decomposition framework, the time evolution of single-exciton states was simulated. Crucially, rather than relying on classical master equations, localized phase-damping channels (Kraus operators) were applied directly to the qubits to act as a computational proxy for the phononic bath of the biological environment.

Results: The quantum simulations successfully reproduced the oscillatory population dynamics characteristic of coherent energy transfer under closed-system conditions. Furthermore, the introduction of the digital dephasing noise accelerated transport to the target reaction center node, demonstrating a simulator-based reproduction of Environment-Assisted Quantum Transport (ENAQT).

Conclusions: Digital quantum simulators offer a promising, resource-efficient methodological framework for modeling the dissipative quantum mechanics of biological systems. This computational approach suggests that explicit qubit noise modeling can serve as a functional proxy for biological thermal baths, potentially reducing the overhead required by classical HEOM computations in quantum biology.