Flowers-Jacobs Nathan E, Fox Anna E, Dresselhaus Paul D, Schwall Robert E, Benz Samuel P
National Institute of Standards and Technology, Boulder, Colorado 80305 USA.
IEEE Trans Appl Supercond. 2016 Sep;26(6). doi: 10.1109/TASC.2016.2532798. Epub 2016 Feb 19.
The root-mean-square (rms) output voltage of the NIST Josephson arbitrary waveform synthesizer (JAWS) has been doubled from 1 V to a record 2 V by combining two new 1 V chips on a cryocooler. This higher voltage will improve calibrations of ac thermal voltage converters and precision voltage measurements that require state-of-the-art quantum accuracy, stability, and signal-to-noise ratio. We achieved this increase in output voltage by using four on-chip Wilkinson dividers and eight inner-outer dc blocks, which enable biasing of eight Josephson junction (JJ) arrays with high-speed inputs from only four high-speed pulse generator channels. This approach halves the number of pulse generator channels required in future JAWS systems. We also implemented on-chip superconducting interconnects between JJ arrays, which reduces systematic errors and enables a new modular chip package. Finally, we demonstrate a new technique for measuring and visualizing the operating current range that reduces the measurement time by almost two orders of magnitude and reveals the relationship between distortion in the output spectrum and output pulse sequence errors.
通过在低温冷却器上组合两个新的1V芯片，美国国家标准与技术研究院（NIST）的约瑟夫森任意波形合成器（JAWS）的均方根（rms）输出电压从1V翻倍至创纪录的2V。这种更高的电压将改善交流热电压转换器的校准以及需要达到最先进的量子精度、稳定性和信噪比的精密电压测量。我们通过使用四个片上威尔金森分频器和八个内外直流模块实现了输出电压的提升，这使得仅通过四个高速脉冲发生器通道的高速输入就能对八个约瑟夫森结（JJ）阵列进行偏置。这种方法将未来JAWS系统所需的脉冲发生器通道数量减半。我们还在JJ阵列之间实现了片上超导互连，这减少了系统误差并启用了一种新的模块化芯片封装。最后，我们展示了一种测量和可视化工作电流范围的新技术，该技术将测量时间减少了近两个数量级，并揭示了输出频谱失真与输出脉冲序列误差之间的关系。
