Quantum dot qubit devices implemented in semiconductor heterostructures

Abstract

To realize the universal quantum computation, it is necessary to achieve the called quantum bit or qubit in a physical system. Semiconductor heterostructure with 2-dimesional electron gas(2DEG) are possible candidates for the qubit system. In this thesis, AlGaAs/GaAs and Si/SiGe heterostructures are investigated for qubit implementation. Apparatus for low-temperature experiment and measurement electronics are demonstrated. Electromagnetic field simulation using Finite Element Method(FEM) is done for high frequency measurement circuit and sample design. Procedures for sample fabrication are also illustrated. Finally, Characteristics of the sample was analyzed through high frequency and quantum hall measurement in low temperature. Measurement result showed that single electron control in quantum dot and future qubit application of the device are possible in AlGaAs/GaAs system. Quantum hall measurement on Si/SiGe structures confirmed 2-dimentional transport in the structure and possibility of the wafers for the future quantum dot qubit devices.