Majorana qubit decoherence by quasiparticle poisoning

TL;DR

This paper investigates how quasiparticle poisoning impacts the coherence of Majorana qubits in nanowire-superconductor systems, revealing that quasiparticle tunneling can significantly limit qubit dephasing times, posing challenges for quantum computing.

Contribution

The study provides analytical and numerical analysis of quasiparticle-induced decoherence in Majorana qubits, highlighting the impact of residual quasiparticles on qubit stability.

Findings

Quasiparticle tunneling can cause rapid dephasing of Majorana qubits.

Residual non-equilibrium quasiparticles are present at low temperatures.

Dephasing times may be too short for effective qubit manipulation.

Abstract

We consider the problem of quasiparticle poisoning in a nanowire-based realization of a Majorana qubit, where a spin-orbit-coupled semiconducting wire is placed on top of a (bulk) superconductor. By making use of recent experimental data exhibiting evidence of a low-temperature residual non-equilibrium quasiparticle population in superconductors, we show by means of analytical and numerical calculations that the dephasing time due to the tunneling of quasiparticles into the nanowire may be problematically short to allow for qubit manipulation.