Readout of Majorana bound states via Landau-Zener transition

TL;DR

This paper proposes a robust, non-demolition protocol for reading out Majorana bound state parity using Landau-Zener transitions in a Majorana island coupled to a double quantum dot, enabling step-by-step state collapse detection.

Contribution

It introduces a novel measurement protocol that maps Majorana parity to charge states via Landau-Zener transitions, allowing for weak and projective measurements.

Findings

Single sweep-and-detection performs weak measurement of parity.

Approximately ten runs project superposition to definite parity.

Protocol is robust to low-frequency charge fluctuations.

Abstract

Reading out Majorana bound states (MBSs) is essential both to verify their non-Abelian property and to realize topological quantum computation. Here, we construct a protocol to measure the parity of two MBSs in a Majorana island coupled to double quantum dot (DQD). The parity information is mapped to the charge state of the DQD through Landau-Zener transition. The operation needed is sweeping the bias of the DQD, which is followed by charge sensing. In the case without fine-tuning, a single run of sweep-and-detection implement a weak measurement of the parity. We find that in general a sequence of about ten runs would completely project a superposition state to either parity, and the charge detection in each run records how the state of MBSs collapses step by step. Remarkably, this readout protocol is of non-demolition and robust to low frequency charge fluctuation.