Quasiparticle poisoning dynamics of a quantum dot coupled to a superconductor

The recent demonstration of a minimal Kitaev chain, hosting “poor man’s Majorana” states, has laid the groundwork for the development of prototypical parity qubits. The coherence times for this type of qubit are upper bounded by the parity lifetime of the individual Kitaev chains. Quasiparticle poisoning events will alter the total fermionic parity, causing the qubit to leak out of its computational subspace. To understand the quasiparticle poisoning (QPP) dynamics of such systems, we study the QPP rate of a quantum dot (QD) coupled to a superconductor in a hybrid InSb-Al nanowire. Utilizing an integrated charge sensor, we find a QPP rate on the order of a millisecond. We demonstrate that the QD effectively acts as a quasiparticle trap for the superconductor.

*We acknowledge Microsoft and the Dutch Organization for Scientific Research (NWO) for funding support.