A quasiparticle-protected superconducting qubit
Researchers extended gap engineering beyond Josephson junctions to protect superconducting qubits from quasiparticle poisoning caused by optical fields. They used a niobium device with gold-on-niobium ground planes and strongly gap-engineered aluminum junctions, showing it withstands over ten times more optical power before relaxation than an all-aluminum qubit. This suggests engineering the energy landscape beyond the junction significantly boosts qubit resilience against radiation and optical noise.