| 摘要(英) |
Owing to Coulomb blockade effect, the number of charges in a single-electron system is fixed. The charge in the system can be add or subtract only when energy given to the system is higher than charging energy of the system. With this feature, single-electron devices are suitable for studying single-electron tunneling events, such as Cooper pair splitting or Andreev reflection.
We fabricated a normal metal-insulator-superconductor-insulator-normal metal (NISIN) box as a three-island single-electron device. The NISIN-box consists of an aluminum superconductor island (S) and two cupper normal metal islands (N1, N2). S island is linked to N1 and N2 via two insulating barriers (I). Each island couples to a nearby gate electrode capacitively. We apply voltages on the gate electrodes to change the free energy of the NISIN-box, and therefore to force the electrons tunneling within the box. We place two single-electron transistors (SETs) as charge sensors to detect the charge state of the box and tunneling events in the box.
SET measurements help us to observe tunneling events. To properly identify all tunneling events, we simulate the stability diagrams of the system to compare the stability diagrams from experiments. The simulated stability diagrams are well matched to the experimental ones, and therefore gives us information for the tunneling events in the NISIN-box.
We further study the rate of cotunneling in the NISIN-box, an important error source of the quantum current standard. We could also fabricate a similar NISIN-box to study Cooper pair splitting.
Summary of each chapters:
Chapter 1: Theorem and application of single-electron device. In our experiment, the main devices we used are hybrid single-electron box and hybrid single-electron transistor.
Chapter 2: The information about processes and technologies of the device fabrication.
Chapter 3: Simulation of stability diagrams of the NISIN-box. The simulation is compared with the stability diagrams of experiments. Then we can identify the charge tunneling events
Chapter 4: Conclusion and future work. |
| 參考文獻 |
1. Likharev, K.K., Single-electron devices and their applications. Proceedings of the Ieee, 1999. 87(4): p. 606-632.
2. Wasshuber, C.; Available from: http://www.iue.tuwien.ac.at/phd/wasshuber/node23.html.
3. Keller, M.W., et al., A seven-junction electron pump: design, fabrication, and operation. Instrumentation and Measurement, IEEE Transactions on, 1997. 46(2): p. 307-310.
4. Devoille, L., et al., Quantum metrological triangle experiment at LNE: measurements on a three-junction R-pump using a 20 000: 1 winding ratio cryogenic current comparator. Measurement Science and Technology, 2012. 23(12): p. 124011.
5. Kleine, A., Experiments on nonlocal processes in NS devices. 2010, University of Basel.
6. Maisi, V., et al., Real-time observation of discrete Andreev tunneling events. Physical review letters, 2011. 106(21): p. 217003.
7. Pekola, J.P., et al., Hybrid single-electron transistor as a source of quantized electric current. Nature Physics, 2007. 4(2): p. 120-124.
8. Sun, C.-H., et al., Experimental determination of the elastic cotunneling rate in a hybrid single-electron box. Applied Physics Letters, 2014. 104(23): p. 232601. |
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