Charge sensing to probe the quasiparticle poisoning lifetime of an Andreev bound state

Quasiparticle poisoning causes dephasing in superconducting-semiconducting hybrid qubits, and the poisoning time could prove to be a limiting factor in the operation of such qubits. One way to extract these times is to perform fast charge/parity sensing measurements. Quantum dots have been widely used as sensors to read out the charge occupation of neighbouring quantum dots. Here we study a quantum dot coupled to an Andreev bound state (ABS), defined in an InSbAs/Al two-dimensional electron gas. We use radio frequency reflectometry to read out the charge state of the ABS. As the ABS goes through a singlet-doublet transition, we see clear shifts in the sensing dot signal. We show progress toward extracting quasiparticle poisoning lifetimes from such measurements.