Department of Physics,
NanjingUniversity,
Nanjing, 210093,
P.R.China Phone: (025)83685553
Fax: (025)83595535
Home: (025)86260455
Email: yuyang@nju.edu.cn
Education:
University of Kansas , Lawrence, KS
Ph.D. Department of Physics & Astronomy, Experimental Condensed Matter Physics, October 2002.
Dissertation: Coherent Quantum Phenomena of Macroscopic Variables in Josephson Tunnel Junctions.
Nanjing University , Nanjing, China
Master of Science. Department of Physics, Experimental Condensed Matter Physics, July 1995.
Thesis: Doping Effect in Bi-2212 High-T c Superconductors
Nanjing University, Nanjing, China
Bachelor of Science. Physics, July 1990
Research Experience:
Nanjing University, Department of Physics (June 2005 – present)
Professor (Changjiang Program).
Quantum computation with superconducting qubits.
Massachusetts Institute of Technology , Research Laboratory of Electronics (October 2002 – June 2005)
Postdoctoral Associate. Advisor: Professor Terry P. Orlando
Quantum computation with superconducting persistent current (PC) qubits.
Supervised and helped graduate and undergraduate students setting up dilution refrigerator, assembling microwave injection system, building low noise measurement circuitry, designing superconducting circuits, taking data, and performing data analysis.
? Measured the dissipation induced decoherence time of PC qubits ~ 25 m s.
? Demonstrated Mach-Zehnder interfermetry of Nb PC qubits.
University of Kansas, Department of Physics and Astronomy (January 1998 – October 2002) Graduate Research Assistant. Advisor: Professor Siyuan Han.
Macroscopic quantum phenomena and quantum computation with Josephson tunnel junction qubits.
Set up dilution refrigerator, assembled microwave injection system, built low noise measurement circuitry, wrote data acquisition program and took data, and performed data analysis and numerical simulation.
? Demonstrated macroscopic quantum coherent oscillation for the first time ( SCIENCE 296, 889).
? Measured decoherence time of Josephson junctions for the first time ( SCIENCE 293, 1457).
? Performed first arbitrary rotation of a single Josephson junction qubit.
These works are breakthrough in fundamental quantum mechanics as well as quantum computation with superconducting qubits, as highlighted in SCIENCE ( 296 , 861, in perspectives) , PHYSICS TODAY (June 2002, in Search & Discovery ), and SCIENTIFIC AMERICAN (August 2002, in News Scan ).
Nanjing University, Department of Physics (September 1992 – December 1997)
Graduate Research Assistant. Advisor: Professor Xixian Yao and Judy Wu.
High T c superconductors, films, and Josephson junctions
Fabricated high-T c ceramic superconductors and films; fabricated YBCO and HBCCO SIS junctions using photo lithography, e-beam lithography, and e-beam writing; tested high-T c grain boundary Josephson junctions; conducted T c and magnetization measurement; performed data analysis.
? Fabricated Hg-1212 superconducting film using laser ablation method for the first time.
? Investigated sodium doping effect in high-T c superconductors.
? Developed a new method to extract U ( J ) of high T c superconductor.
Activities/Honors:
American Physical Society, Division of Condensed Matter Physics , 1998 – present
Sigma Xi full member, 2003
Excellent Graduate Student, Nanjing University, 1993
Guanghua Fellowship, 1994
Publications:
1? W. D. Oliver, Yang Yu , J. C. Lee, K. K. Berggren, L. S. Levitov, and T. P. Orlando, “Mach-Zehnder Interferometry in a Strongly Driven Superconducting Qubit,” Science 310 , 1653 (2005).
2? Yang Yu , D. Nakada, Janice Lee, B. Singh, D. Crankshaw, T. P. Orlando, William Oliver and K. K. Berggren “Energy Relaxation Time between Macroscopic Quantum Levels in a Superconducting Persistent Current Qubits,”
Phys. Rev. Lett. . 92 , 117904 (2004)
3? Yang Yu and Siyuan Han, “Resonant escape over an oscillating barrier in under-damped Josephson tunnel junctions,” Phys. Rev. Lett. 91 , 127003 (2003).
4? Yang Yu , Yu Zhang, Siyuan Han, and Zhen Wang, “Coherent Control of Macroscopic Quantum States In a Josephson Junction,” IEEE Transactions on Applied Superconductivity , 13 , 998 (2003).
5? Shao-Xiong Li, Yang Yu , Wei Qiu, Siyuan Han, and Zhen Wang, “Efficiency of Underdamped dc SQUIDs as Readout Devices for Flux Qubits,” IEEE Transactions on Applied Superconductivity , 13 , 982 (2003).
6? Yang Yu , Yu Zhang, Wei Qiu, Shaoxiong Li, Siyuan Han, and Zhen Wang, “Observation of temporal evolution of an unstable macroscopic quantum system with nanoseconds resolution,” Supercond. Sci. Technol . 15 , 555 (2002).
7? Yang Yu , Siyuan Han, Xi Chu, Shih-I Chu, and Zhen Wang, “Coherent temporal oscillations of macroscopic quantum states in a Josephson Junction,” Science 296, 889 (2002) . (Please also see SCIENCE 296 , 861, in perspectives , PHYSICS TODAY June 2002, in Search & Discovery , and SCIENTIFIC AMERICAN August 2002, in News Scan ).
8? Shaoxiong Li, Yang Yu , Yu Zhang, Wei Qiu, Siyuan Han, and Zhen Wang, “Quantitative Study of Macroscopic Quantum Tunneling in a dc SQUID: A System with Two Degrees of Freedom,” Phys. Rev. Lett. 89, 098301 (2002).
9? Siyuan Han, Yang Yu , Xi Chu, Shih-I Chu, and Zhen Wang, “Time-resolved measurement of dissipation-induced decoherence in a Josephson junction,” Science 293 , 1457 (2001).
10? Yang Yu , S. L. Yan, L. Fang, Y. Y. Xie, J. Z. Wu, Siyuan Han, H. Shimakage, and Zhen Wang, “Fabrication of HgBa 2 CaCu 2 O y grain boundary junctions using the cation exchange method,” Supercond. Sci. Technol. 12 , 1020 (1999).
11? Yi-Yuan Xie, Judy Z. Wu, Shaolin Yan, Yang Yu , Tolga Aytug, Lang Fang and S. C. Tidrow, “Elimination of air detrimental effect using Tl-stabilized precursor for epitaxial HgBa 2 CaCu 2 O 6 thin films,”
Physica C 328 , 241 (1999).
12? T. Aytug , Y. Yu , S. L. Yan, Y. Y. Xie and J. Z. Wu, “Response of superconducting characteristics of Hg-based high- T c thin films to photolithographic processes,” Physica C 325 , 56 (1999).
13? Yi-Yuan Xie, Judy Z. Wu, Albert A. Gapud, Yang Yu and Yin Xin, “Synthesis of Hg-1223 superconductors using a cation-exchange process ,” Physica C 322 , 19 (1999).
14? Y. Yu , Z. Y. Zeng, X. N. Xu, H. M. Shao, M. J. Qin, X. Jin, X. X. Yao, X. S. Rong, B. Ying and Z. X. Zhao, “Temperature dependence of the critical current determined from magnetic relaxation in HgBa 2 Ca 2 Cu 3 O 8+ δ ,”
Physica C 298 , 240 (1998).
15? J Zhou, Z. M. Ji, S. Z. Yang, P. H. Wu, Y. Yu , H. M. Shao, X. X. Yao, M. Y. Lai, W. L. Zhang, “ Growth of highly oriented (Hg,Pb)-based superconducting thin films on LaAlO 3 substrates by pulsed laser ablation,”
Journal of materials science Letters , 17, 271 (1998).
16? Y. Yu , Z. Y. Zheng, M. J. Qin, X. X. Yao, L. P. Ma, H. C. Li and L. Li . , “Characteristic exponents near vortex-glass temperature in GdBa 2 Cu 3 O 7-d film,” Physica C 292 , 197 (1997).
17? Y. Yu , X. N. Xu, H. L. Ji, H. M. Shao, M. J. Qin, X. Jin, X. X. Yao, X. S. Rong, B. Ying, Z. X. Zhao, “Dependence of flux-creep activation energy upon current density in HgBa 2 Ca 2 Cu 3 O y ,” Physica C 280, 205 (1997).
18? Y. Yu , X. N. Xu, W. M. Chen, A. M. Sun, S. Y. Ding, X. Jin, X. X. Yao, “Structural and physical properties of Al substituted Y 1-x Al x Ba 2 Cu 3 O y ,” Physica C 282-287, 517 (1997).
19? Y. Yu , X. N. Xu, X. Jin, S. Y. Ding, Z. Y. Zheng, X. X. Yao, “T c enhancement in silver substituted Bi 1.7 Pb 0.3 Sr 2-x Ag x Ca 2 Cu 3 O y ,” Physica C 282-287, 845 (1997).
20? Y. Yu , X. N. Xu, Z. Y. Zheng, X. Jin, X. X. Yao, “Extract U(J) and time constant from magnetic relaxation experiments,” Supercond. Sci. Technol. 10, 568 (1997).
21? Y. Yu , X. N. Xu, X. Jin, S. Y. Ding, Z. Y. Zheng, X. X. Yao, G. J. Shen, “A new family of Cuprates with 1212 structure: SnBa 2 CaCu 2 O y ,” Physica status solidi (a) 163, 177 (1997).
22? Y. Yu, H. M. Shao, Z. Y. Zheng, A. M. Sun, M. J. Qin, X. N. Xu, S. Y. Ding, X. Jin, X. X. Yao, J. Zhou, Z. M. Ji, S. Z. Yang, W. L. Zhang, “HgBa 2 Ca 2 Cu 3 O y superconducting thin films prepared by laser ablation,” Physica C 289 , 199 (1997).
23? X. X. Yao, Y. Yu , M. J. Qin, “U-J relation determined from magnetic relaxation,” Physica C 282-287, 2195 (1997).
24? A. M. Sun, X. N. Xu, Y. Yu , Z. Y. Zeng, X. Jin, X. X. Yao, and Z. G. Fan, “Glassy exponent of melt textured YBCO extracted from magnetic hysteresis loops with various field sweep rates,” Physica C 282-287 , 2393 (1997).
25? W. M. Chen, S. Liang, X. S. Wu, Y. Yu , X. Jin, and S. S. Jiang, “A structure transition of Fe-doped superconducting cuprates,” Journal of Superconductivity , 10, 51 (1997).
26? A. M. Sun, X. N. Xu, Y. Yu , Z. Y. Zeng, X. Jin, X. X. Yao, and Z. G. Fan, “Dependence of the glassy exponent on field and temperature in textured YBCO specimen,” Journal of Superconductivity , 10, 559 (1997).
27? J Zhou, S. Z. Yang, Z. M. Ji, P. H. Wu, Y. Yu , H. M. Shao, X. X. Yao, M. Y. Lai, W. L. Zhang, “ Fabrication of highly c-axis oriented Hg-Pb-Ba-Ca-Cu-O thin films,” Supercond. Sci. Technol . 10 , 998 (1997).
28? Z. Y. Zeng, Y. Yu , A. M. Sun, X. N. Xu, S. Y. Ding, X. X. Yao, “Frequency dependence of ac magnetic response in type-II superconductors,” Physica C 272 , 101 (1996).
29? Z. Y. Zeng, Y. Yu , A. M. Sun, X. N. Xu, S. Y. Ding, X. X. Yao, R. H. Tao, X. Ling, “Surface pinning and influence of field reduction on magnetic relaxation in YBa 2 Cu 3 O 7 bulk sample,” Physica C 269, 297 (1996).
30? Y. Yu , W. M. Chen, X. L. Xu, A. M. Sun, S. Y. Ding, X. Jin, X. X. Yao, Z. M. Ji, Q. H. Chen, “Synthesis and supercondcting properties of the Ca 1-x Na x LaBaCu 3 O y system,” Physica Status Solidi (a) 155 , 467 (1996).
31? Y. Yu , X. Jin, S. Y. Ding, Z. Y. Zhen, X. X. Yao, and G. J. Shen, “Effect of silver in Bi 1.7 Pb 0.3 Sr 2-x Ag x Ca 2 Cu 3 O y ,” Appl. Phys. Lett. 67, 545 (1995).
32? Y. Yu , X. Jin, S. Y. Ding, Z. Y. Zhen, X. X. Yao, G. J. Shen, “The superconductivity of Bi 1.7 Pb 0.3 Sr 2-x Ag x Ca 2 Cu 3 O y ,” Physica Status Solidi (a) 151 , K9 (1995).
33? Y. Yu , X. Jin, D. X. Cai, X. X. Yao, C. Hu, K. Y. Ding, D. Feng, “The superconductivity of sodium doped Bi 2 Sr 2 CaCu 2 O 8+y ,” Physica Status Solidi (a) 146 , K33 (1994).
Presentations:
1? Yang Yu , Yu Zhang, Siyuan Han, and Zhen Wang, 2002 Applied Superconductivity Conference (August 4-9, Houston, TX) , “ Coherent control of macroscopic quantum states in a Josephson junction.”
2? Yang Yu , Shaoxiong Li, Siyuan Han, and Zhen Wang, 2002 Applied Superconductivity Conference (August 4-9, Houston, TX) , “ Low-frequency excess noise in NbN-AlN-NbN Josephson tunnel junctions .”
3? Shaoxiong Li, Yang Yu , Wei Qiu, Siyuan Han, Zhen Wang , 2002 Applied Superconductivity Conference (August 4-9, Houston, TX) , “ Investigation of underdamped dc SQUIDs for qubit readout .”
4? Yang Yu , Yu Zhang, Wei Qiu, Shaoxiong Li, Siyuan Han, and Zhen Wang, 8th International Superconductive Electronics Conference (June 19-22, 2001, Osaka, Japan) , “Observation of temporal evolution of an unstable macroscopic quantum system with nanoseconds resolution.”
5? Yang Yu , Yu Zhang, Wei Qiu, Shaoxiong Li, and Siyuan Han , Annual Meeting of the American Physical Society (March 12-16, 2001, Seattle, WA) , “ Characterization of Josephson devices using nano-second time domain measurement technique. ”
6? Yang Yu , Wei Qiu, and Siyuan Han, Annual Meeting of the American Physical Society (March 20-24, 2000, Minneapolis, MN) , “ Measurement of dissipation barrier of Josephson tunnel junctions. ”
7? Yang Yu , S. L. Yan, L. Fang, Y. Y. Xie, J. Z. Wu, Siyuan Han, H. Shimakage, and Zhen Wang, 7th International Superconductive Electronics Conference (June 21-25, 1999, Berkeley, CA), “Fabrication of HgBa 2 CaCu 2 O y grain boundary junctions using the cation exchange method.”