Interference and parity blockade in transport through a Majorana box

TL;DR

This paper theoretically studies charge transport in a Majorana box, revealing a parity blockade effect that can be used for qubit initialization, readout, and distinguishing between clean and disordered systems.

Contribution

It introduces the concept of parity blockade in Majorana boxes and explores its applications for quantum computing and system diagnostics.

Findings

Current can be blocked when two Majoranas couple to the same lead.

Parity blockade enables high-fidelity qubit initialization and readout.

Transport measurements can differentiate between clean and disordered Majorana systems.

Abstract

A Majorana box - two topological superconducting nanowires coupled via a trivial superconductor - is a building block in devices aiming to demonstrate nonabelian physics, as well as for topological quantum computer architectures. We theoretically investigate charge transport through a Majorana box and show that current can be blocked when two Majoranas couple to the same lead, fixing their parity. In direct analogy to Pauli spin blockade in spin qubits, this parity blockade can be used for fast and high-fidelity qubit initialization and readout, as well as for current-based measurements of decoherence times. Furthermore, we demonstrate that transport can distinguish between a clean Majorana box and a disordered box with additional unwanted Majorana or Andreev bound states.