Decoherence of Majorana qubits by 1/f noise

TL;DR

Majorana qubits in superconductor-semiconductor nanowires are significantly affected by 1/f charge noise, which causes decoherence through quasiparticle excitations, challenging their error suppression claims.

Contribution

This paper reveals the impact of 1/f noise on Majorana qubits and highlights the need for engineering strategies similar to those used in superconducting qubits.

Findings

1/f noise induces quasiparticle excitations causing decoherence.

Increasing nanowire capacitance reduces internal decoherence.

External quasiparticles become a dominant decoherence source.

Abstract

Qubits based on Majorana zero modes (MZMs) in superconductor-semiconductor nanowires have attracted intense interest due to claims that their error rates are suppressed exponentially with increasing nanowire length or decreasing temperature. However, here we show that these qubits are subject to substantial decoherence resulting from the high-frequency components of 1/f charge noise, which is ubiquitous in the materials surrounding the nanowire. This process excites quasiparticles in the bulk of the topological superconductor that cause qubit decoherence even under otherwise ideal conditions. Increasing nanowire capacitance suppresses this mechanism but exposes the qubits to decoherence from externally-generated quasiparticles. Therefore, achieving high-fidelity MZM qubits will require engineering strategies and compromises very similar to those needed for conventional superconducting qubits.