Braidonium: a braiding quantum circuit based on the $4\pi$ Josephson effect

TL;DR

This paper introduces Braidonium, a topological quantum circuit utilizing the $4 extpi$ Majorana-Josephson effect for braiding and readout, involving a tri-junction of Majorana nanowires and fluxonium coupling.

Contribution

It presents a novel braiding quantum circuit design based on the $4 extpi$ Majorana-Josephson effect, with protocols for control and readout using flux-based methods.

Findings

Demonstrates feasible braiding and readout with realistic materials.

Analyzes flux-based control protocols for topological qubits.

Proposes a practical device architecture for topological quantum computation.

Abstract

We propose a topological qubit in which braiding and readout are mediated by the $4\pi$ Majorana-Josephson effect. The braidonium device consists of three Majorana nanowires that come together to make a tri-junction; in order to control the superconducting phase differences at the tri-junction the nanowires are enclosed in a ring made of a conventional superconductor; and in order to perform initialization/readout one of the nanowires is coupled to a fluxonium qubit through a topological Josephson junction. We analyze how flux-based control and readout protocols can be used to demonstrate braiding and qubit operation for realistic materials and circuit parameters.