Gyrator operation using Josephson mixers

摘要

Nonreciprocal microwave devices, such as circulators, are useful in routingquantum signals in quantum networks and protecting quantum systems againstnoise coming from the detection chain. However, commercial, cryogeniccirculators, now in use, are unsuitable for scalable superconducting quantumarchitectures due to their appreciable size, loss, and inherent magnetic field.We report on the measurement of a key nonreciprocal element, i.e., the gyrator,which can be used to realize a circulator. Unlike state-of-the-art gyrators,which use a magneto-optic effect to induce a phase shift of $\pi$ betweentransmitted signals in opposite directions, our device uses the phasenonreciprocity of a Josephson-based three-wave-mixing device. By coupling twoof these mixers and operating them in noiseless frequency-conversion mode, weshow that the device acts as a nonreciprocal phase shifter whose phase shift iscontrolled by the phase difference of the microwave tones driving the mixers.Such a device could be used to realize a lossless, on-chip, superconductingcirculator suitable for quantum-information-processing applications.