Fan YANG
PD Researcher, Institute of Scientific and Industrial Research (ISIR), Osaka University- Field of Specialty：
- Condensed matter physics
- Topics of Research：
- (C01) Novel Phenomena in Electron Fluids with Broken Inversion Symmetry
RESEARCH
Quantum computers promise a powerful system for quickly solving several key calculations, which would normally take days (or longer) using conventional computers. The most talked about computation where quantum computers are required is the factorization by prime numbers (using Shor's algorithm), which has applications in decoding crypted data. The major problem with realizing a multiple quantum-bit (called q-bit) computer is decoherence, that is, the destruction of the quantum state due to the system interacting with the environment. Quantum decoherence effect limits the time that a computation can take before producing a large error.
Several strategies to increase the quantum coherence times have been proposed and studied. Among them, perhaps the most promising idea is to use Majorana fermions as the q-bits in a quantum computer. A quantum state that is encoded using multiple Majorana fermions is necessarily non-local and is therefore protected from any local sources of decoherence. These states are manipulated by braiding the quasiparticles. This process is energy intensive and therefore less susceptible to noise. While a system that exhibits behavior of a Majorana fermion has not yet been observed, several potential condensed-matter systems where these states exist have been proposed: Majorana fermions are expected to exist in the excitations of the 5/2 quantum Hall state; Majorana fermions may also appear in the vortex core of p-wave superconductors such as Sr2RuO4; furthermore, Majorana fermions have been theorized to appear in the proximity-induced superconducting state of a topological insulator or in a semiconductor nano-wire with a strong spin-orbit coupling.
I wish to contribute my skills to further the search for the Majorana fermion in the systems discussed above. More specifically, I would like to focus on the systems involving nano-fabrications, in which my technical skill excels. An appealing platform that was predicted to host Majorana particles is the proximity-induced superconductivity on the surface of topological insulators. The proposed experiments involve a superconducting thin film sandwiched by two insulating magnets all deposited on the surface of a topological insulator. The Majorana fermions are predicted to be created at the interfaces between the magnet and the superconductor. Multiple modes of detection were proposed, such as looking at crossed Andreev reflections, creating an interferometer structure, and utilizing the phase shift in the superconducting wave function in a Josephson junction.
The realization of a system which exhibits properties of a Majorana fermion is a very complex process. Nevertheless, Prof. Ando's lab has all the essential ingredients that are necessary for the proposed research. The outline of my research plan is the following:
1) Prepare high-quality thin films of conventional superconductors and ferromagnetic insulators on top of a topological-insulator thin film using the electron-beam deposition in the existing UHV chamber, which is connected to the MBE chamber for the topological-insulator film growths. Epitaxially-grown Bi2Se3 topological insulator films, which form the base of the device, are already available in Prof. Ando's lab.
2) Using the nano-fabrication facility of the host researcher's institute, I will prepare the necessary device structure. Here, my skills in nano-fabrication are directly applicable.
3) Make the measurements using the existing dilution refrigerator. I have enough experience in operating a dilution fridge.
EDUCATION
- 2007
- B.Sc., Dept. of Physics, Nanjing University
- 2012
- Ph.D., Institute of Physics, Chinese Academy of Science
HONORS AND AWARDS
- 2009
- Director Recognition Award, Institute of Physics, Chinese Academy of Sciences
- 2009
- Excellent Students Awards, Graduate University, Chinese Academy of Sciences
- 2010
- Director Recognition Award, Institute of Physics, Chinese Academy of Sciences
- 2011
- Director Recognition Award, Institute of Physics, Chinese Academy of Sciences
- 2011
- Excellent Students Awards, Graduate University, Chinese Academy of Sciences
SELECTION OF PUBLICATIONS
"Strong superconducting proximity effect in Pb-Bi2Te3 hybrid structures",
F. M. Qu*, F. Yang*, J. Shen*, Y. Ding, J. Chen, Z. Q. Ji, G. T. Liu, J. Fan, X. N. Jing,
C. L. Yang and L. Lu,
* : co-first-authors
Sci. Rep. 2, 339 (2012)
"Proximity Effect at Superconducting Sn-Bi2Se3 Interface",
Fan Yang, Yue Ding, Fanming Qu, Jie Shen, Jun Chen, Zhongchao Wei, Zhongqing Ji,
Guangtong Liu, Jie Fan, Changli Yang, Tao Xiang, and Li Lu,
Phys. Rev. B 85, 104508 (2012)
"Aharonov-Casher Effect in Bi2Se3 Square-Ring Interferometers",
Fanming Qu, Fan Yang, Jun Chen, Jie Shen, Yue Ding, Jiangbo Lu, Yuanjun Song,
Huaixin Yang, Guangtong Liu, Jie Fan, Yongqing Li, Zhongqing Ji, Changli Yang, and
Li Lu,
Phys. Rev. Lett. 107, 016802 (2011)
"Gate-Voltage Control of Chemical Potential and Weak Antilocalization in Bi2Se3",
J. Chen, H. J. Qin, F. Yang, J. Liu, T. Guan, F. M. Qu, G. H. Zhang, J. R. Shi, X. C. Xie,
C. L. Yang, K. H. Wu, Y. Q. Li, and L. Lu
Phys. Rev. Lett. 105, 176602 (2010)
