Detection and Manipulation of Majorana Fermions in Circuit QED

TL;DR

This paper proposes a superconducting circuit device that detects and manipulates Majorana fermions with high fidelity, enabling quantum readout and gate operations for topological qubits while maintaining noise insensitivity.

Contribution

It introduces a novel circuit design interfacing Majorana fermions with circuit QED for topologically protected qubit readout and manipulation, including phase gate implementation.

Findings

High-fidelity single-shot readout of Majorana qubits

Implementation of an arbitrary phase gate on topological qubits

Charge sensitivity better than 10^{-4} e/√Hz with >1 MHz bandwidth

Abstract

Motivated by recent experimental progress towards the measurement and manipulation of Majorana fermions with superconducting circuits, we propose a device interfacing Majorana fermions with circuit quantum electrodynamics. The proposed circuit acts as a charge parity detector changing the resonance frequency of a superconducting $\lambda/4$ - resonator conditioned on the parity of charges on nearby gates. Operating at both charge and flux sweet spots, this device is highly insensitive to environmental noise. It enables high-fidelity single-shot quantum non demolition readout of the state of a pair of Majorana fermions encoding a topologically protected qubit. Additionally, the interaction permits the realization of an arbitrary phase gate on the topological qubit, closing the loop for computational completeness. Away from the charge sweet spot, this device can be used as a highly sensitive charge detector with a sensitivity better than $10^{-4} \text{e} / \sqrt{\text{Hz}}$ and bandwidth larger than $1$ MHz.