| Efficient solar-energy harvesting is fundamental to solar cell technology. Recent experiments in nanotechnology focus on quantum structures, e.g. carbon nanotubes or quantum dots, to improve harvesting efficiency. The purpose of this research is to demonstrate the viability of employing quantum phase synchronization to improve light-harvesting efficiency.;We design a novel, nanostructured, phase-synchronized light-harvesting architecture utilizing feedback control principles. For the nonlinear light-harvesting dynamical system, we would like to formulate a phase controller which achieves the desired state propagation with minimum processing overhead and thus reduces the cost of implementation. We consider two types of phase controllers, namely a classical phase controller and a quantum phase controller.;The classical phase controller consists of a tracking controller and a proportional-integral regulator. The advantage of the classical phase controller is its ease of design and that it provides the behavior of the phase controller at a macroscopic level. The disadvantage is that it cannot control the state of the dynamical system at a quantum level due to measurement disturbance on the system. Nonetheless, the classical phase controller formulation serves as an initial step toward deriving the theoretical description of the quantum phase controller.;The quantum phase controller is a piecewise-affine quantum dynamical system and it interacts coherently with the light-harvesting system. In contrast to a classical controller formulation in which the classical control law is represented by a function of state variables, the quantum control law is represented by dynamical operators which operate on quantum states. This type of fully coherent quantum control, in which the controller is physically integrated with the system to be controlled, can achieve desired state propagation goals with minimum processing overhead and delay. We design the quantum controller by developing a quantization scheme based on a classical nonlinear controller. The quantization scheme leads to controllers which may be realized using quantum elements such as semiconductor quantum wells.;Our numerical simulations demonstrate that our phase controllers have the ability to control phase synchronization, thus enabling efficient light harvesting. |
