A compact and tunable forward coupler based on high-impedance superconducting nanowires

Abstract

Developing compact, low-dissipation, cryogenic-compatible microwave electronics is essential for scaling up low-temperature quantum computing systems. In this paper, we demonstrate an ultra-compact microwave directional forward coupler based on high-impedance slow-wave superconducting-nanowire transmission lines. The coupling section of the fabricated device has a footprint of $416\mu {\mathrm{m}}^2$. At 4.753 GHz, the input signal couples equally to the through port and forward-coupling port (50:50) at $-6.7\mathrm{dB}$ with $-13.5\mathrm{dB}$ isolation. The coupling ratio can be controlled with DC bias current or temperature by exploiting the dependence of the kinetic inductance on these quantities. The material and fabrication-process are suitable for direct integration with superconducting circuits, providing a practical solution to the signal distribution bottlenecks in developing large-scale quantum computers.

References in corpus (6)

• Supplementary information for "Quantum supremacy using a programmable superconducting processor"
• Microwave photonics with superconducting quantum circuits
• Implementation of low-loss superinductances for quantum circuits
• Josephson junction microwave modulators for qubit control
• Demonstration of microwave multiplexed readout of DC biased superconducting nanowire detectors
• Demonstration of a superconducting nanowire microwave switch