# Multiqubit Greenberger-Horne-Zeilinger state generated by synthetic magnetic field in circuit QED

## TL;DR

This paper presents a method to generate multiqubit GHZ states in circuit QED by using a synthetic magnetic field created through modulated qubit-qubit coupling, enabling robust entanglement generation.

## Contribution

The authors introduce a novel scheme utilizing a synthetic magnetic field to generate GHZ states in superconducting qubits, extending the method to arbitrary multiqubit states.

## Key findings

- Successful generation of three-qubit GHZ state.
- The scheme is robust against operation errors and environmental noise.
- Extension to arbitrary multiqubit GHZ states is feasible.

## Abstract

We propose a scheme to generate Greenberger-Horne-Zeilinger (GHZ) state for N superconducting qubits in a circuit QED system. By sinusoidally modulating the qubit-qubit coupling, a synthetic magnetic field has been made which broken the time-reversal symmetry of the system. Directional rotation of qubit excitation can be realized in a three-qubit loop under the artificial magnetic field. Based on the special quality that the rotation of qubit excitation has different direction for single- and double-excitation loops, we can generate three-qubit GHZ state and extend this preparation method to arbitrary multiqubit GHZ state. Our analysis also shows that the scheme is robust to various operation errors and environmental noise.