Quasiparticle trapping by orbital effect in a hybrid superconducting-semiconducting circuit

Understand

The tunneling of quasiparticles (QPs) across Josephson junctions (JJs) detrimentally affects the coherence of superconducting and charge-parity qubits, and is shown to occur more frequently in magnetic fields.

• Here we demonstrate the parity lifetime to survive in excess of 50$\,\mathrm{\mu}$s in magnetic fields up to 1$\,$T, utilising a semiconducting nanowire transmon to detect QP tunneling in real time.
• We exploit gate-tunable QP filters and find magnetic-field-enhanced parity lifetimes, consistent with increased QP trapping by the ungated nanowire due to orbital effects.
• Our findings highlight the importance of QP trap engineering for building magnetic-field compatible hybrid superconducting circuits.