biostudies-literatureUnknown13(1)Pan XKey-Area Research and Development Program of Guang-Dong ProvinceIdentifying, quantifying, and suppressing decoherence mechanisms in qubits are important steps towards the goal of engineering a quantum computer or simulator. Superconducting circuits offer flexibility in qubit design; however, their performance is adversely affected by quasiparticles (broken Cooper pairs). Developing a quasiparticle mitigation strategy compatible with scalable, high-coherence devices is therefore highly desirable. Here we experimentally demonstrate how to control quasiparticle generation by downsizing the qubit, capping it with a metallic cover, and equipping it with suitable quasiparticle traps. Using a flip-chip design, we shape the electromagnetic environment of the qubit above the superconducting gap, inhibiting quasiparticle poisoning. Our findings support the hypotNature communications7196https://www.ebi.ac.uk/biostudies/studies/S-EPMC9684549biostudies-literatureEngineering superconducting qubits to reduce quasiparticles and charge noise.PMC9684549Pan XLi JNie LYu DWei WZhang LLiu SZhou YYuan HJiang ZHHu LCatelani GYan FfalseEngineering superconducting qubits to reduce quasiparticles and charge noise.Identifying, quantifying, and suppressing decoherence mechanisms in qubits are important steps towards the goal of engineering a quantum computer or simulator. Superconducting circuits offer flexibility in qubit design; however, their performance is adversely affected by quasiparticles (broken Cooper pairs). Developing a quasiparticle mitigation strategy compatible with scalable, high-coherence devices is therefore highly desirable. Here we experimentally demonstrate how to control quasiparticle generation by downsizing the qubit, capping it with a metallic cover, and equipping it with suitable quasiparticle traps. Using a flip-chip design, we shape the electromagnetic environment of the qubit above the superconducting gap, inhibiting quasiparticle poisoning. Our findings support the hypot2022-01-01T00:00:00Z2022 Nov2025-04-18T14:59:46.314Z2025-04-07T01:26:38.48ZS-EPMC96845493641828610.1038/s41467-022-34727-2