MIT News  August 26, 2020 Superconducting qubits are used for high-fidelity operations. However, the density of the broken Cooper pairs, referred to as quasiparticles, is orders of magnitude higher than the value predicted at equilibrium suggesting that another generation mechanism exists. A team of researchers in the US (MIT, Pacific Northwest National Laboratory, MIT Lincoln Laboratory) has provided evidence that ionizing radiation from environmental radioactive materials and cosmic rays contributes to this observed difference. The effect of ionizing radiation leads to an elevated quasiparticle density, which they predict would ultimately limit the coherence times of superconducting qubits. They demonstrated that […]