Flux-tunable heat sink for quantum electric circuits

TL;DR

This paper demonstrates a tunable heat sink device for superconducting qubits, enabling efficient photon dissipation and potential rapid initialization of quantum states in superconducting microwave circuits.

Contribution

The authors experimentally realize a flux-tunable heat sink with coupled resonators, allowing on-demand control of photon dissipation in superconducting circuits.

Findings

Loaded quality factor tunable from >10^5 to a few thousand

Efficient photon dissipation when resonators are in resonance

Quantitative agreement with theoretical model

Abstract

Superconducting microwave circuits show great potential for practical quantum technological applications such as quantum information processing. However, fast and on-demand initialization of the quantum degrees of freedom in these devices remains a challenge. Here, we experimentally implement a tunable heat sink that is potentially suitable for the initialization of superconducting qubits. Our device consists of two coupled resonators. The first resonator has a high quality factor and a fixed frequency whereas the second resonator is designed to have a low quality factor and a tunable resonance frequency. We engineer the low quality factor using an on-chip resistor and the frequency tunability using a superconducting quantum interference device. When the two resonators are in resonance, the photons in the high-quality resonator can be efficiently dissipated. We show that the corresponding loaded quality factor can be tuned from above $10^5$ down to a few thousand at 10 GHz in good quantitative agreement with our theoretical model.