Superconducting Quantum Computing with Multiplexed Flux DAC for Zero-Power Bias Control

Researchers at the University of California, Santa Barbara have developed a multiplexed flux digital-to-analog converter (DAC) that allows the magnetic flux in a superconducting loop to be quantitatively changed by pulsing in two currents to the contro…
Researchers at the University of California, Santa Barbara have developed a multiplexed flux digital-to-analog converter (DAC) that allows the magnetic flux in a superconducting loop to be quantitatively changed by pulsing in two currents to the control device. The two input currents act as a logical AND circuit such that the device can be selected in a multiplexed manner in an array of devices, allowing it to be easily scaled. The change in flux occurs with zero power dissipation, permitting the device to be used at ultra-low dilution refrigerator temperatures. This multiplexing allows large numbers of digital-to-analog converters to be placed on a chip with a small number of control wires — without substantially increasing the local chip temperature and/or without causing transitions to undesired energy states.