Scalable Designs for Quasiparticle-Poisoning-Protected Topological Quantum Computation with Majorana Zero Modes

TL;DR

This paper proposes scalable topological quantum computer designs using Majorana zero modes, emphasizing measurement-only operations, simplified architecture without T-junctions, and protection against quasiparticle poisoning.

Contribution

It introduces a scalable architecture for topological quantum computing with Majorana modes, avoiding T-junctions and utilizing measurement protocols for quantum operations.

Findings

Designs are compatible with scalable quantum computing.

Quasiparticle poisoning is mitigated by charging energy.

Clifford operations are performed via measurement protocols.

Abstract

We present designs for scalable quantum computers composed of qubits encoded in aggregates of four or more Majorana zero modes, realized at the ends of topological superconducting wire segments that are assembled into superconducting islands with significant charging energy. Quantum information can be manipulated according to a measurement-only protocol, which is facilitated by tunable couplings between Majorana zero modes and nearby semiconductor quantum dots. Our proposed architecture designs have the following principal virtues: (1) the magnetic field can be aligned in the direction of all of the topological superconducting wires since they are all parallel; (2) topological $T$-junctions are not used, obviating possible difficulties in their fabrication and utilization; (3) quasiparticle poisoning is abated by the charging energy; (4) Clifford operations are executed by a relatively standard measurement: detection of corrections to quantum dot energy, charge, or differential capacitance induced by quantum fluctuations; (5) it is compatible with strategies for producing good approximate magic states.