We present time-domain electrical measurements and simulations of the quantized voltage pulses that are generated from series-connected Josephson junction (JJ) arrays. The transmission delay of the JJ array can lead to a broadening of the net output pulse, depending on the direction of the output pulse propagation relative to the input bias pulse. To demonstrate this, we compare time-domain measurements of output pulses from radio-frequency Josephson arbitrary waveform synthesizer (RF-JAWS) circuits fabricated with two different output measurement configurations, so that the backward-propagating and forward-propagating pulses can be measured. Measurements were made on arrays with 1200 and 3600 JJs and show that the net backward-propagating output pulse is broadened by timing delays in the JJ array, whereas the net forward-propagating output pulse is insensitive to delay effects and can theoretically be further scaled to longer JJ array lengths without significant output pulse broadening. These measurements match well with simulations and confirm the expectation that the net output pulses arise from the time-delayed superposition of individual JJ output pulses from the series array of JJs. The measurements and analysis shown here have important implications for the realization of RF-JAWS circuits to be used as quantum-based reference sources for communications metrology.

中文翻译：

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约瑟夫森结阵列中的量化脉冲传播

我们提出了串联约瑟夫森结 (JJ) 阵列生成的量化电压脉冲的时域电气测量和模拟。JJ 阵列的传输延迟可能导致净输出脉冲展宽，具体取决于输出脉冲相对于输入偏置脉冲的传播方向。为了证明这一点，我们比较了使用两种不同输出测量配置制造的射频约瑟夫森任意波形合成器（RF-JAWS）电路的输出脉冲的时域测量，以便可以测量向后传播和向前传播的脉冲。对具有 1200 和 3600 JJ 的阵列进行测量，结果表明，净反向传播输出脉冲因 JJ 阵列中的定时延迟而变宽，而净正向传播输出脉冲对延迟效应不敏感，理论上可以进一步缩放至更长的 JJ 阵列长度，且没有明显的输出脉冲展宽。这些测量结果与仿真吻合良好，并证实了净输出脉冲是由来自 JJ 串联阵列的各个 JJ 输出脉冲的延时叠加产生的预期。这里显示的测量和分析对于实现 RF-JAWS 电路（用作通信计量的基于量子的参考源）具有重要意义。