Fidelity and visibility loss in Majorana qubits by entanglement with environmental modes

Abstract

Majorana qubits based on Majorana bound states (MBSs) are believed to be topologically protected and therefore robust to noise. However, when the MBSs are coupled to gapless modes, such as phonons or electromagnetic modes, the quantum information is stored in entangled MBS-environment states. Moreover, the combined system becomes gapless and even though the quantum information is still topologically protected, it is challenging to read out the quantum information when the measurement device only couples to the MBS. The paper discusses the readout errors that occur when performing projective measurement on the MBSs in this situation.