Optimal efficiency of quantum transport in a disordered trimer

Area of Science:

• Quantum physics
• Biophysics
• Spectroscopy

Background:

• Disordered quantum networks, common in light-harvesting complexes, feature peripheral rings and inner reaction centers (RCs).
• Eigenstates in peripheral rings separate into superradiant and subradiant states, crucial for optimizing excitation transfer efficiency.
• In disordered systems, static disorder couples previously decoupled subradiant states to superradiant states, indirectly linking them to the RC.

Purpose of the Study:

• To analyze optimal excitation transfer conditions in a three-level quantum system (trimeric structure) with an initial excitation on a subradiant state.
• To investigate the complex interplay between reaction center energy, disorder strength, and system parameters influencing transfer efficiency.
• To understand the impact of dynamical noise on resonance structures and energy transfer.

Main Methods:

• Theoretical analysis of a three-level quantum system modeling disordered light-harvesting complexes.
• Investigation of excitation transfer dynamics initiated from a subradiant state.
• Examination of the influence of static disorder and dynamical noise on energy transfer pathways and resonance conditions.

Main Results:

• Optimal disorder strength is found to be comparable to the superradiant coupling.
• Optimal detuning between the initial state and RC energy is highly system-dependent.
• When superradiant coupling exceeds the energy gap, resonance with the initial subradiant state is optimal; otherwise, resonance with a virtual dressed state is favored.
• Dynamical noise introduces an additional incoherent resonance peak at the superradiant state energy.

Conclusions:

• The study reveals complex dependencies of optimal energy transfer on disorder and system parameters in disordered quantum networks.
• Initiating excitation from subradiant states offers unique pathways for optimizing energy transfer.
• Dynamical noise significantly alters energy transfer resonance, creating new optimal conditions.
• Findings have implications for designing artificial light-harvesting systems and understanding natural processes.