Macroscopic Greenberger-Horne-Zeilinger and W States in Flux Qubits

TL;DR

This paper explores the generation and robustness of GHZ and W entangled states in macroscopic superconducting flux qubits, proposing a phase coupling method to achieve strong interactions and stable entanglement.

Contribution

It introduces a theoretical scheme for creating GHZ and W states in flux qubits using phase coupling, demonstrating their stability against flux fluctuations.

Findings

GHZ state formed at the ground state of three flux qubits

W state generated in an excited state

Both states are robust against external flux fluctuations

Abstract

We investigate two types of genuine three-qubit entanglement, known as the Greenberger-Horne-Zeilinger(GHZ) and W states, in a macroscopic quantum system. Superconducting flux qubits are considered theoretically in order to generate such states. A phase coupling is proposed to offer enough strength of interactions between qubits. While an excited state can be the W state, the GHZ state is formed at the ground state of the three flux qubits. The GHZ and W states are shown to be robust against external flux fluctuations for feasible experimental realizations.