  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.
