Deterministic generation of Greenberger-Horne-Zeilinger entangled states of cat-state qubits in circuit QED

TL;DR

This paper proposes a deterministic, high-fidelity method to generate GHZ entangled states of three cat-state qubits in circuit QED, using a superconducting transmon qutrit, with potential extension to more qubits.

Contribution

It introduces a measurement-free, efficient scheme for creating GHZ states of cat-state qubits in circuit QED, reducing decoherence and enabling scalability.

Findings

Numerical simulations confirm high-fidelity GHZ state generation.

The method suppresses decoherence by keeping the qutrit in the ground state.

The approach is extendable to N-qubit GHZ states.

Abstract

We present an efficient method to generate a Greenberger-Horne-Zeilinger (GHZ) entangled state of three cat-state qubits (cqubits) via circuit QED. The GHZ state is prepared with three microwave cavities coupled to a superconducting transmon qutrit. Because the qutrit remains in the ground state during the operation, decoherence caused by the energy relaxation and dephasing of the qutrit is greatly suppressed. The GHZ state is created deterministically because no measurement is involved. Numerical simulations show that high-fidelity generation of a three-cqubit GHZ state is feasible with present circuit QED technology. This proposal can be easily extended to create a $N$-cqubit GHZ state ($N\geq 3$), with $N$ microwave or optical cavities coupled to a natural or artificial three-level atom.