Exact and efficient quantum simulation of open quantum dynamics for various of Hamiltonians and spectral densities

TL;DR

This paper demonstrates an exact quantum simulation method for open quantum systems, applied to photosynthetic models with various Hamiltonians and spectral densities, showing improved efficiency and potential for broad applicability.

Contribution

The paper extends a previously proposed quantum simulation approach to various Hamiltonians and spectral densities, demonstrating its efficiency and generality in modeling open quantum dynamics.

Findings

Enhanced energy transfer efficiency in dimerized geometries with strong intra-cluster couplings.

Optimal energy transfer occurs when the energy gap matches the spectral density peak.

The approach effectively simulates different spectral densities, including Ohmic, sub-Ohmic, and super-Ohmic.

Abstract

Recently, we have theoretically proposed and experimentally demonstrated an exact and efficient quantum simulation of photosynthetic light harvesting in nuclear magnetic resonance (NMR), cf. B. X. Wang, \textit{et al.} npj Quantum Inf.~\textbf{4}, 52 (2018). In this paper, we apply this approach to simulate the open quantum dynamics in various photosynthetic systems with different Hamiltonians. By numerical simulations, we show that for Drude-Lorentz spectral density the dimerized geometries with strong couplings within the donor and acceptor clusters respectively exhibit significantly-improved efficiency. Based on the optimal geometry, we also demonstrate that the overall energy transfer can be further optimized when the energy gap between the donor and acceptor clusters matches the peak of the spectral density. Moreover, by exploring the quantum dynamics for different types of spectral densities, e.g. Ohmic, sub-Ohmic, and super-Ohmic spectral densities, we show that our approach can be generalized to effectively simulate open quantum dynamics for various Hamiltonians and spectral densities. Because $\log_{2}N$ qubits are required for quantum simulation of an $N$-dimensional quantum system, this quantum simulation approach can greatly reduce the computational complexity compared with popular numerically-exact methods.