Half-flux-quantum (HFQ) circuits store and propagate half-flux quanta. The basic circuit element is a 0-π SQUID, which is a superconducting quantum interference device with a conventional Josephson junction (0-junction) and a π-shifted ferromagnetic junction (π-junction). A 0-π 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-π SQUIDs with two 0-junctions and a π-junction which serves as a π phase-shifter. We simulated 0-0-π 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-π SQUIDs. We estimated the power consumption and maximum operating frequency of an HFQ Josephson transmission line based on 0-0-π SQUIDs. When operating at 43.5 GHz, the power dissipation of a single element composed of a 0-0-π SQUID and a bias resistor fell to about 0.165 nW when biased at 60 μV. The LV-HFQ circuit is potentially more power-efficient than all other currently available superconducting logic circuits.

半通量量子（HFQ）电路存储和传播半通量量子。基本电路元件是0-πSQUID，它是具有常规约瑟夫逊结（0结）和π位移铁磁结（π结）的超导量子干涉装置。0-πSQUID在没有外部磁场的情况下可实现很小的临界电流，从而降低了功耗。设置带有两个0接点和一个用作π相移器的π接点的0-0-πSQUID很容易。我们模拟了由低偏置电压驱动的基于0-0-πSQUID的HFQ电路，称为LV-HFQ电路。在这些电路中，开关结点不需要分流电阻器，因为0-0-πSQUID的电流-电压特性没有滞后现象。我们根据0-0-πSQUID估算了HFQ Josephson传输线的功耗和最大工作频率。当工作在43.5 GHz时，由0-0-πSQUID和偏置电阻组成的单个元件的功耗在偏置为60μV时降至约0.165 nW。LV-HFQ电路可能比所有其他当前可用的超导逻辑电路具有更高的功率效率。