Simulating non-Markovian Dynamics Using Noisy Intermediate Scale Quantum (NISQ) Computers.

Open quantum system dynamics has gained research interest due to its direct applications to quantum dynamics in the condensed phase, and quantum error correction. Recent advances reveal intriguing phenomena like coherence trapping, enhanced quantum entanglement, information backflow, etc. In physical chemistry, developing methods for simulating charge and exciton transfer in various systems is central. Many of these processes are quantum mechanical and non-Markovian, making classical simulations costly.



NISQ computer simulations of open quantum systems are still emerging. This work presents a novel quantum algorithm based on Kraus operators that capture the exact non-Markovian quantum effect at finite temperature. The implementation of the Kraus operators on the quantum machine uses a combination of singular value decomposition (SVD) and the optimal Walsh operators that result in shallow circuits. We demonstrate the feasibility of the algorithm by simulating the spin-boson dynamics and the exciton transfer in Fenna-Matthews-Olson (FMO) complex in photosynthesis. The NISQ machine results show very good agreement with the exact ones. The algorithm development along this line could leverage the advantage of quantum computers to simulate quantum systems that are beyond the reach of classical computers.