Abstract
Quantum effects such as the environment assisted quantum transport (ENAQT) displayed in photosynthetic Fenna–Mathews–Olson (FMO) complex has been simulated on analog quantum simulators. Digital quantum simulations offer greater universality and flexibility over analog simulations. However, digital quantum simulations of open quantum systems face a theoretical challenge; one does not know the solutions of the continuous time master equation for developing quantum gate operators. We give a theoretical framework for digital quantum simulation of ENAQT by introducing new quantum evolution operators. We develop the dynamical equation for the operators and prove that it is an analytical solution of the master equation. As an example, using the dynamical equations, we simulate the FMO complex in the digital setting, reproducing theoretical and experimental evidence of the dynamics. The framework gives an optimal method for quantum circuit implementation, giving a log reduction in complexity over known methods. The generic framework can be extrapolated to study other open quantum systems.
Highlights
Quantum simulators are devices that can turn the exponential scaling of resources needed to simulate and understand properties of complex quantum systems on classical computers into a favourable polynomial overhead
Recently a number of studies have remarkably shown that noise can facilitate transmission of energy in quantum simulators through a process called environment assisted quantum transport (ENAQT) [6]
We have provided a model for digital quantum simulation of energy transfer in open quantum systems
Summary
Quantum simulators are devices that can turn the exponential scaling of resources needed to simulate and understand properties of complex quantum systems on classical computers into a favourable polynomial overhead. Their study does not include quantum jumps and the interplay of quantum and dissipative effects which are the salient features of the environment assisted quantum walk These previous studies led us to explore and characterize the theoretical model with a general framework for digital quantum simulation of the dynamics in chemical complexes along with FMO complex as a specific example. We develop a theoretical framework for digital simulation of environment assisted energy transfer in open quantum systems. The main challenge in developing discrete time evolution operators for digital quantum simulation is that one needs to solve the master equation for which solutions are otherwise not known. The evolution equation is generalised to incorporate variable strength of system–bath interaction which helps in controlling the dynamics by tuning the level of noise This gives a theoretical model for the digital quantum simulation of ENAQT with tunable bath coupling.
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