Low-power high-speed half-flux-quantum circuits driven by low bias voltages
Low-power high-speed half-flux-quantum circuits driven by low bias voltages
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DOI：
10.1088/1361-6668/abcaac
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发表时间：
2021-02-01
影响因子：
3.6
通讯作者：
Fujimaki, Akira
中科院分区：
文献类型：
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作者：
Li, Feng;Takeshita, Yuto;Fujimaki, Akira
半磁通量子（HFQ）电路用于存储和传输半磁通量子。其基本电路元件是0 - π超导量子干涉器件（SQUID），它是一种包含常规约瑟夫森结（0结）和π移相铁磁结（π结）的超导量子干涉装置。0 - π SQUID在无外部磁场时能实现较小的临界电流，从而降低功耗。利用两个0结和一个作为π移相器的π结，很容易搭建0 - 0 - π SQUID。我们对由低偏置电压驱动的基于0 - 0 - π SQUID的HFQ电路进行了模拟，这种电路被称为低电压HFQ（LV - HFQ）电路。在这些电路中，切换结无需分流电阻，因为0 - 0 - π SQUID的电流 - 电压特性不存在磁滞现象。我们估算了基于0 - 0 - π SQUID的HFQ约瑟夫森传输线的功耗和最大工作频率。当在43.5吉赫兹下工作时，由一个0 - 0 - π SQUID和一个偏置电阻组成的单个元件，在60微伏偏置下的功耗降至约0.165纳瓦。LV - HFQ电路有可能比目前所有其他可用的超导逻辑电路在能效上更具优势。
Half-flux-quantum (HFQ) circuits store and propagate half-flux quanta. The basic circuit element is a 0-pi SQUID, which is a superconducting quantum interference device with a conventional Josephson junction (0-junction) and a pi-shifted ferromagnetic junction (pi-junction). A 0-pi SQUID achieves a small critical current in the absence of an external magnetic field, thus reducing power consumption. It is easy to set up 0-0-pi SQUIDs with two 0-junctions and a pi-junction which serves as a pi phase-shifter. We simulated 0-0-pi SQUID-based HFQ circuits driven by low bias voltages, referred to as LV-HFQ circuits. In these circuits, shunt resistors are not required for switching junctions because there is no hysteresis in the current-voltage characteristics of 0-0-pi SQUIDs. We estimated the power consumption and maximum operating frequency of an HFQ Josephson transmission line based on 0-0-pi SQUIDs. When operating at 43.5 GHz, the power dissipation of a single element composed of a 0-0-pi SQUID and a bias resistor fell to about 0.165 nW when biased at 60 mu V. The LV-HFQ circuit is potentially more power-efficient than all other currently available superconducting logic circuits.