Quasiparticles in Superconducting Quantum Circuits

Abstract:

Superconducting electrical circuits can be used for quantum computing, quantum simulation, ultra-low-noise amplification, and precision sensing. However, quasiparticles--electron-like single-particle excitations of the superconducting condensate--can cause loss and noise, limiting the performance of these devices. The generation mechanisms, behavior, and annihilation channels of these quasiparticles are still poorly understood, hindering efforts to eliminate them from circuits. I will review the evidence for different quasiparticle models, show measurements using Andreev bound states as quasiparticle traps, and discuss future experiments that will determine the best ways to mitigate the harmful effects of quasiparticles.