Generation of multicomponent atomic Schrödinger cat states of up to 20 qubits

TLDR

Multipartite entangled states are crucial for many quantum information applications, yet generating and verifying them on scalable, controllable platforms remains a challenge. The study aims to demonstrate deterministic generation of large‑scale multipartite entanglement on a solid‑state quantum processor, with implications for quantum metrology and information processing. A one‑axis twisting Hamiltonian is engineered so that initialized qubits coherently evolve into multicomponent atomic Schrödinger cat states, including GHZ states, at specific times. The authors successfully produced an 18‑qubit GHZ state and up to 20‑qubit multicomponent atomic Schrödinger cat states on a 20‑qubit superconducting processor.

Abstract

Multipartite entangled states are crucial for numerous applications in quantum information science. However, the generation and verification of multipartite entanglement on fully controllable and scalable quantum platforms remains an outstanding challenge. We report the deterministic generation of an 18-qubit Greenberger-Horne-Zeilinger (GHZ) state and multicomponent atomic Schrödinger cat states of up to 20 qubits on a quantum processor, which features 20 superconducting qubits, also referred to as artificial atoms, interconnected by a bus resonator. By engineering a one-axis twisting Hamiltonian, the system of qubits, once initialized, coherently evolves to multicomponent atomic Schrödinger cat states-that is, superpositions of atomic coherent states including the GHZ state-at specific time intervals as expected. Our approach on a solid-state platform should not only stimulate interest in exploring the fundamental physics of quantum many-body systems, but also enable the development of applications in practical quantum metrology and quantum information processing.