The single Cooper pair transistor: a macroscopic quantum system
The single Cooper pair transistor: a macroscopic quantum system
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单库珀对晶体管：宏观量子系统
DOI：
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发表时间：
1995
期刊：
影响因子：
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通讯作者：
P. Joyez
中科院分区：
文献类型：
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作者：
P. Joyez
在两个小面积（100 nm x 100 nm）超导隧道结串联连接的系统中，倾向于施加相位的约瑟夫森效应与倾向于设置岛电荷的中心电极（设备的“岛”）中的充电效应竞争。通过在电容耦合到岛的电极（“栅”电极）上施加电压，可以仲裁这种竞争以有利于任一效果。这一点可以特别地在可以流过结的超电流上看到：它被栅极电压周期性地调制（因此该系统被称为“晶体管”）。当岛的两个电荷态相对于静电能简并时，这种调制显示出尖锐的峰。这样，系统就处于一个没有经典描述的状态：它处于一个相干态叠加。在这篇论文中，我们实验证明了这种晶体管的行为，我们分析了理论和实际问题，可以防止观察的相干叠加态通过调制的超电流。特别是，我们表明，在岛上的电子数的奇偶校验必须严格控制和连接到电路的阻抗起着至关重要的作用，在设置测量的超电流的大小。
In a system where two small-area (100 nm x 100 nm) superconducting tunnel junctions are connected in series, the Josephson effect which tends to impose the phase competes with the charging effects in the central electrode (the "island" of the device) which tend to set the charge of the island. By applying a voltage on an electrode capacitively coupled to the island (the "gate" electrode) one can arbitrate this competition in favour of either effect. This is can be seen in particular on the supercurrent which can flow through the junctions : it is modulated periodically by the gate voltage (hence the name of "transistor" given to the system). This modulation shows sharp peaks when two charge states of the island are degenerate with respect to the electrostatic energy. The system is then in a state which has no classical description : it is in a coherent superposition of states. In this thesis we demonstrate experimentally the behaviour of this transistor and we analyse the theoretical and practical problems which can prevent the observation of the coherent superposition of states through the modulation of the supercurrent. In particular we show that the parity of the electron number in the island must be rigorously controlled and that the impedance connected to the circuit plays a crucial role in setting the magnitude of the measured supercurrent.