Generation of Greenberger-Horne-Zeilinger States on Two-Dimensional Superconducting-Qubit Lattices via Parallel Multiqubit-Gate Operations

Abstract

A recent major technological breakthrough in superconducting circuits is the realization of more than 50 qubits arranged on two-dimensional (2D) lattices with tunable nearest-neighbor couplings. We propose a protocol to generate Greenberger-Horne-Zeilinger (GHZ) states on 2D superconducting-qubit lattices by applying multiqubit controlled-$i$swap gates in parallel. The multiqubit gate can be naturally implemented based on an effective three-body interaction, which can be synthesized with appropriate detunings and coupling strengths between qubits. We simulate the preparation process of GHZ states with realistic parameters, and show a $37$-qubit GHZ state can be generated with a controlled-$i$swap depth of $3$. Our proposal provides a more promising method of generating GHZ states on the latest 2D superconducting-qubit architectures and will stimulate the preparation of multiqubit entangled states based on multiqubit gates.