Quasi-lattices of qubits for generating inequivalent multipartite entanglements

TL;DR

This paper explores how inhomogeneous coupling in superconducting qubit quasi-lattices facilitates multi-photon resonances, enabling the generation of inequivalent GHZ and W multipartite entangled states, with potential applications in quantum information processing.

Contribution

It introduces a model showing inhomogeneous coupling in qubit quasi-lattices promotes multi-photon resonances and the creation of distinct multipartite entanglement states, including GHZ and W types.

Findings

Inhomogeneous coupling enhances multi-photon resonances.

Multi-photon resonances generate inequivalent GHZ and W states.

The model verifies promotion of GHZ state generation in a 3-qubit quasi-lattice.

Abstract

The mesoscopic scale of superconducting qubits makes their inter-spacings comparable to the scale of wavelength of a circuit cavity field to which they commonly couple. This comparability results in inhomogeneous coupling strengthes for each qubit and hence asynchronous Rabi excitation cycles among the qubits that form a quasi-lattice. We find that such inhomogeneous coupling benefits the formation of multi-photon resonances between the single-mode cavity field and the quasi-lattice. The multi-photon resonances lead, in turn, to the simultaneous generation of inequivalent GHZ and W types of multipartite entanglement states, which are not transformable to each other through local operations with classical communications. Applying the model on the 3-qubit quasi-lattice and using the entanglement measures of both concurrence and 3-tangle, we verify that the inhomogeneous coupling specifically promotes the generation of the totally inseparable GHZ state.