Scalable Creation of Long-Lived Multipartite Entanglement

We demonstrate the deterministic generation of multipartite entanglement based on scalable methods. Four qubits are encoded in Ca+40, stored in a microstructured segmented Paul trap. These qubits are sequentially entangled by laser-driven pairwise gate operations. Between these, the qubit register is dynamically reconfigured via ion shuttling operations, where ion crystals are separated and merged, and ions are moved in and out of a fixed laser interaction zone. A sequence consisting of three pairwise entangling gates yields a four-ion Greenberger-Horne-Zeilinger state |ψ=(1/2)(|0000+|1111), and full quantum state tomography reveals a state fidelity of 94.4(3)%. We analyze the decoherence of this state and employ dynamic decoupling on the spatially distributed constituents to maintain 69(5)% coherence at a storage time of 1.1 sec.Fil: Kaufmann, H.. University Mainz. Institute of Inorganic and Analytical Chemistry, Johannes Gutenberg; AlemaniaFil: Ruster, T.. University Mainz. Institute of Inorganic and Analytical Chemistry, Johannes Gutenberg; AlemaniaFil: Schmiegelow, Christian Tomás. Universidad de Buenos Aires; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Física de Buenos Aires. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Física de Buenos Aires; ArgentinaFil: Luda, Marcelo Alejandro. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Física de Buenos Aires. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Física de Buenos Aires; ArgentinaFil: Kaushal, V.. University Mainz. Institute of Inorganic and Analytical Chemistry, Johannes Gutenberg; AlemaniaFil: Schulz, Juan Sebastián. University Mainz. Institute of Inorganic and Analytical Chemistry, Johannes Gutenberg; AlemaniaFil: Von Lindenfels, D.. University Mainz. Institute of Inorganic and Analytical Chemistry, Johannes Gutenberg; AlemaniaFil: Schmidt-Kaler, F.. University Mainz. Institute of Inorganic and Analytical Chemistry, Johannes Gutenberg; AlemaniaFil: Poschinger, U. G.. University Mainz. Institute of Inorganic and Analytical Chemistry, Johannes Gutenberg; Alemani