1. A solution searching system by quantum dots comprising: an energy supply quantum dot having an energy level where exciters are excited in response to a supplied input light; a plurality of output display quantum dots each of which is formed in a larger volume than the energy supply quantum dot, has a resonant level where exciters are injected from the energy level in the input quantum dot, and can emit an output light based on energy discharging of the exciters transiting from the resonant level to a lower level; a light detection unit for detecting a light emission state of the output light for each of the output display quantum dots; a control light supply unit capable of supplying a control light to the output display quantum dots to excite other exciters to the lower level, and thereby controlling energy discharging of the exciters transiting to the lower level; and a feedback control unit for controlling a control light to be supplied by the control light supply unit for each of the output display quantum dots based on the light emission state of the output light for each of the output display quantum dot detected by the light detection unit and previously-input search problem information, wherein the feedback control unit repeatedly performs supply control of the control light thereby to finally display a search solution for the search problem information based on the light emission state of the output light from each of the output display quantum dots read by the light detection unit.