PTB关于实现量子计量三角的研究

Realization of the Quantum Metrological Triangle at PTB

PTB量子计量三角的组成部分为量子霍尔电阻标准、约瑟夫森电压标准和一个电子计数电容标准(ECCS),而电容的校准能力在量子计量三角的建立过程中起了很重要的作用。为了计算电子个数,采用了一个被称为r电子泵的低温真空电容,其电容值为1pF的十进制整数值。目前整个设备尚未正式运行,某些部件还处于研制阶段。虽然低温电容值在循环后的重复性好于10-6,但是要使量子计量三角型的不确定度达到预期的10-7以内,30 s的电子测量的停留时间还是相对较短。此外,计算电容的校准能力和量子霍尔电阻均有所改进。

The realization of the quantum metrological triangle at the Physikalisch-Technische Bundesanstalt(PTB)is based on calibration capabilities for the capacitance towards a Quantum-Hall resistance,the Josephson voltage standard,and an Electron Counting Capacitance Standard(ECCS)experiment.For transferring electrons one by one onto a cryogenic vacuum capacitor with a decade capacitance of 1 pF a so-called r-pump will be used.All components are presently under investigation before the complete measurement setup will be employed.While the cryogenic capacitance value shows better than 10-6 reproducibility after cycling,the measured dwell times of the electrons of 30 seconds could be too short for closing the triangle with the aimed uncertainty of less than 10-7.Furthermore,calibration capabilities for the capacitance to a calculable capacitor and towards a Quantum-Hall resistance are improved.