Coherent dynamics of a Josephson charge qubit
Coherent dynamics of a Josephson charge qubit
复制标题
DOI：
10.1103/physrevb.69.140503
复制
发表时间：
2004-04-01
影响因子：
3.7
通讯作者：
Delsing, P
中科院分区：
文献类型：
--
作者：
Duty, T;Gunnarsson, D;Delsing, P
我们利用单电子晶体管（SET）射频读出（rf-SET），将单库珀对盒（SCB）与静电计电容耦合，制作了约瑟夫森电荷量子比特。观察到2 e的电荷量子化，并使用微波光谱来提取盒的约瑟夫森和充电能量。我们使用非常快的直流脉冲进行相干操作的SCB和观察量子振荡的时间的电荷，坚持类似或等于10纳秒。观察到的振荡的对比度是高的，并同意从有限的E-J/E-C比和有限的上升时间的直流脉冲的预期。此外，我们能够证明几乎100%的初始电荷态极化。当弛豫时间T-1小于测量时间T-meas时，我们还提出了一种确定弛豫时间T-1的方法。
We have fabricated a Josephson charge qubit by capacitively coupling a single-Cooper-pair box (SCB) to an electrometer based upon a single-electron transistor (SET) configured for radio-frequency readout (rf-SET). Charge quantization of 2e is observed and microwave spectroscopy is used to extract the Josephson and charging energies of the box. We perform coherent manipulation of the SCB by using very fast dc pulses and observe quantum oscillations in time of the charge that persist to similar or equal to10 ns. The observed contrast of the oscillations is high and agrees with that expected from the finite E-J/E-C ratio and finite rise time of the dc pulses. In addition, we are able to demonstrate nearly 100% initial charge state polarization. We also present a method to determine the relaxation time T-1 when it is shorter than the measurement time T-meas.