電路量子電動力學 (circuit quantum electrodynamics) 是一個學習光跟原子量子交互作用的平台，同時，也是實現可擴展的量子電腦最有潛力的方法之一。單一Transmon 量子位元耦合一一維傳輸線共振器在我們實驗室裡被製造出來。我們控制並量測量子位元的狀態藉由色散讀取 (dispersive readout) 跟傑恩斯-卡明斯讀取 (Jaynes-Cummings readout)。從頻譜量測結果，確認我們的電路量子電動力學系統是在強耦 合以及強色散區域，此時量子相干性可維持。我們演示數項指標性的時域控制實驗,如拉比震盪 (Rabi oscillation), 狀態掃描 (state tomography) 以及拉姆齊條紋 (RamseyFringe)。基本的量子位元特徵如鬆弛時間 T1，量子退相干時間 T2 以及耦合強度 g 也可確定, 分別是 T1 ∼ 75 ns,T2 ∼ 134 ns,g ∼ 175 MHz。這篇論文提供了超導電路的基本理論背景以控制跟讀取量子位元狀態。;Circuit quantum electrodynamics (cQED) is a platform to study quantum interaction between light and atom. Also, it is one of the most promising ways to achieve scalable quantum computer. A transmon qubit coupled to a one dimensional transmission line resonator is fabricated in our Lab. We control and measure the qubit state by utilizing the dispersive readout and Jaynes-Cummings readout. From spectroscopy measurements, our cQED system is confirmed in the strong dispersive regime where the quantum coherence effect dominates the system. We demonstrate some hallmark time domain control experiments, such as Rabi oscillation, state tomography, and Ramsey Fringe. The basic characteristic of the qubit, such as relaxation time T1 ∼ 75 ns, decoherence time T2 ∼ 134 ns, and coupling strength g ∼ 175 MHz are then determined. This thesis provides the basic theoretical backgrounds of superconducting circuits and the studies of control and readout of the single qubit.
