The Study On Resonator And Quantum Dot Coupling System

In all possible implementation of quantum computing, gate-controlled quantum dot is a strong candidate that has better compatibility. Resonator, that provides single frequency photons, could couple far apart qubits, realizing the extension of qubit num-bers in quantum computing systems. Starting from these two points, we study problems step by step in order to realize quantum dots and cavity coupling, such as the design and measurement of resonator, the coupling of two-dimensional electron gas and resonator, the interaction of quantum dots and resonator.The main content in this thesis has:1. The research background and basic concept. Introduced the basic knowledge of quantum computing. Discussed the theory frame and experimental phenomena of gate-controlled quantum dot, and charge quantum dot qubit encoding.2. Nano processing technology. Introduced the technology of the semiconductor quantum dot manufacture, low temperature platform and the basic measurement methods of quantum dots.3. Basic knowledge of resonator. Introduced the theory of lumped and distributed resonant circuit, and its quantum description. Discussed the design, manufacture and characterization of the transmission resonator, the reflection resonator, and3D resonator.4. Reflection resonator and its tuning. Introduced a real experiment on reflection resonator, including specific sample structure and measuring method. Studied the tuning design of the resonator by two dimensional electron gas, which could adjust the quality factor in a large range.5. Measurement of the complex admittance of quantum dot by resonator. Intro-duced the experimental method of using reflection resonator to measure isolated quantum dot. Through the amplitude and phase shift of the resonator reflection spectrum, the equivalent resistance and capacitance resistance and isolated quan-tum dot could be deduced and electron tunneling rate can be estimated.6. Circuit-QED(quantum electrodynamics). Introduced the basic concepts, the the-ory analysis of the coupling of resonator and quantum dot. Discussed the param-eter extraction process with the concrete experimental sample.Following are the main innovations of this thesis: 1. Design and realize a new kind of half-wavelength reflection resonator, which is easy to manufacture, convenient for coupling multiple systems. Study a resonator tuning method by two-dimensional electron gas, which can adjust quality factor in a large range by controlling electrode voltage.2. Use high quality factor resonator to realize the measurement of complex admit-tance of nearly isolated quantum dot, which provides a new method for sensitive detection of isolated quantum dot. Confirm the existence of double quantum dots by the honeycomb of the amplitude and phase shift of resonator reflection spec-trum, and calculate electron tunneling rate.3. Simulate and realize of3D resonator structure. Systematically discussed the prac-tical impact of adding dc leads to3D resonator. Test the actual effect by the ex-perimental data4. Study the dipolar coupling of resonator and quantum dots. Get the quantum dots phase diagram in weak dispersive region and fit the coupling parameter.