Quasiparticle Poisoning in a Proximitized Semiconductor Nanowire Qubit*

Topological qubits are predicted to have very long coherence times due to their inherent protection against local perturbations. However, non-parity preserving processes such as quasiparticle poisoning (QPP) set the bandwidth requirements for controlling topological qubits. Quasiparticle poisoning rates have been recorded in conventional superconducting transmon qubits [1, 2] and in hybrid proximitized semiconductor nanowire junctions [3] at zero magnetic field.
Here we perform QPP measurements on nanowire transmons in a magnetic field by monitoring parity-dependent shifts of the transmon’s readout resonator. We investigate the magnetic field dependence of the QPP up to magnetic fields required to reach the topological phase.

[1] D. Riste et al., Nat. Commun. 4, 1913 (2013)
[2] K. Serniak et al., Phys. Rev. Lett. 121, 157701 (2018)
[3] M. Hays et al., Phys. Rev. Lett. 121, 047001 (2018)