Flux-Tunable Dissipation for Superconducting Quantum Circuits

Circuit quantum electrodynamics is one of the most promising approaches for building a large-scale quantum computer. Despite the intensive research in the field, further development steps are still required to obtain this goal. Especially, fast initialization of qubits is beneficial for various error correction codes. Here, we experimentally demonstrate a flux-tunable environment that can potentially be used for qubit initialization [J. Tuorila, et al., npj Quantum Information 3, 27 (2017)]. Our system consists of two coupled resonators: one with a high quality factor, and the other with a low quality factor and a tunable resonance frequency achieved with a superconducting quantum interference device. We can tune the loaded quality factor of the system from above 10⁵ down to a few thousand.