中国物理B ›› 2014, Vol. 23 ›› Issue (2): 20305-020305.doi: 10.1088/1674-1056/23/2/020305

• GENERAL • 上一篇    下一篇

Quantum state measurement in double quantum dots with a radio-frequency quantum point contact

严蕾, 王海霞, 殷雯, 王芳卫   

  1. Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China
  • 收稿日期:2013-08-13 修回日期:2013-09-12 出版日期:2013-12-12 发布日期:2013-12-12
  • 基金资助:
    Project supported by the National Natural Science Foundation of China (Grant No. 11174358) and the National Basic Research Program of China (Grant No. 2010CB833102).

Quantum state measurement in double quantum dots with a radio-frequency quantum point contact

Yan Lei (严蕾), Wang Hai-Xia (王海霞), Yin Wen (殷雯), Wang Fang-Wei (王芳卫)   

  1. Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China
  • Received:2013-08-13 Revised:2013-09-12 Online:2013-12-12 Published:2013-12-12
  • Contact: Yin Wen E-mail:wenyin@aphy.iphy.ac.cn
  • About author:03.65.Yz; 03.67.Lx; 73.23.Hk
  • Supported by:
    Project supported by the National Natural Science Foundation of China (Grant No. 11174358) and the National Basic Research Program of China (Grant No. 2010CB833102).

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摘要： We study the dynamics of two electron spins in coupled quantum dots (CQDs) monitored by a quantum point contact (QPC) detector. Their quantum state can be measured by embedding the QPC in an LC circuit. We derive the Bloch-type rate equations of the reduced density matrix for CQDs. Special attention is paid to the numerical results for the weak measurement condintion under a strong Coulomb interaction. It is shown that the evolution of QPC current always follows that of electron occupation in the right dot. In addition, we find that the output voltage of the circuit can reflect the evolution of QPC current when the circuit and QPC are approximately equal in frequency. In particular, the wave shape of the output voltage can be improved by adjusting the circuit resonance frequency and bandwidth.

关键词: measurement, quantum state, output voltage, circuit parameter

Abstract: We study the dynamics of two electron spins in coupled quantum dots (CQDs) monitored by a quantum point contact (QPC) detector. Their quantum state can be measured by embedding the QPC in an LC circuit. We derive the Bloch-type rate equations of the reduced density matrix for CQDs. Special attention is paid to the numerical results for the weak measurement condintion under a strong Coulomb interaction. It is shown that the evolution of QPC current always follows that of electron occupation in the right dot. In addition, we find that the output voltage of the circuit can reflect the evolution of QPC current when the circuit and QPC are approximately equal in frequency. In particular, the wave shape of the output voltage can be improved by adjusting the circuit resonance frequency and bandwidth.

Key words: measurement, quantum state, output voltage, circuit parameter

中图分类号:  (Decoherence; open systems; quantum statistical methods)

  • 03.65.Yz
03.67.Lx (Quantum computation architectures and implementations) 73.23.Hk (Coulomb blockade; single-electron tunneling)