中国物理B ›› 2009, Vol. 18 ›› Issue (11): 5044-5046.doi: 10.1088/1674-1056/18/11/072

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Nb/Al-AlOx/Nb junctions with controllable critical current density for qubit application

曹文会, 于海峰, 田野, 于洪伟, 任育峰, 陈赓华, 赵士平   

  1. Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China
  • 收稿日期:2009-01-15 修回日期:2009-03-06 出版日期:2009-11-20 发布日期:2009-11-20
  • 基金资助:
    Project supported by the National Natural Science Foundation of China (Grant Nos 10534060 and 10874231) and the Ministry of Science and Technology of China (Grant Nos 2006CB601007, 2006CB921107, and 2009CB929102).

Nb/Al-AlOx/Nb junctions with controllable critical current density for qubit application

Cao Wen-Hui(曹文会), Yu Hai-Feng(于海峰), Tian Ye (田野), Yu Hong-Wei(于洪伟),Ren Yu-Feng (任育峰), Chen Geng-Hua (陈赓华),andZhao Shi-Ping (赵士平)†   

  1. Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China
  • Received:2009-01-15 Revised:2009-03-06 Online:2009-11-20 Published:2009-11-20
  • Supported by:
    Project supported by the National Natural Science Foundation of China (Grant Nos 10534060 and 10874231) and the Ministry of Science and Technology of China (Grant Nos 2006CB601007, 2006CB921107, and 2009CB929102).

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摘要： Nb/Al-AlOx/Nb tunnel junctions with controllable critical current density Jc are fabricated using the standard selective Nb etching process. Tunnel barriers are formed in different oxygen exposure conditions (oxygen pressure P and oxidation time t), giving rise to Jc ranging from 100~A/cm2 to above 2000 A/cm2. Jc shows a familiar linear dependence on P×t in logarithmic scales. We calculate the energy levels of the phase- and flux-type qubits using the achievable junction parameters and show that the fabricated Nb/Al-AlOx/Nb tunnel junctions can be used conveniently for quantum computation applications in the future.

Abstract: Nb/Al-AlOx/Nb tunnel junctions with controllable critical current density Jc are fabricated using the standard selective Nb etching process. Tunnel barriers are formed in different oxygen exposure conditions (oxygen pressure P and oxidation time t), giving rise to Jc ranging from 100 A/cm2 to above 2000 A/cm2. Jc shows a familiar linear dependence on P × t in logarithmic scales. We calculate the energy levels of the phase- and flux-type qubits using the achievable junction parameters and show that the fabricated Nb/Al-AlOx/Nb tunnel junctions can be used conveniently for quantum computation applications in the future.

Key words: Nb junctions, fabrication, superconducting qubit, macroscopic quantum state

中图分类号:  (Critical currents)

  • 74.25.Sv
74.50.+r (Tunneling phenomena; Josephson effects) 73.40.Rw (Metal-insulator-metal structures) 81.65.Cf (Surface cleaning, etching, patterning) 03.67.Lx (Quantum computation architectures and implementations) 74.70.Ad (Metals; alloys and binary compounds)