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arXiv:2210.02936 · Physical Review Letters

Scalable Multipartite Entanglement Created by Spin Exchange in an Optical Lattice

Wei-Yong Zhang, Ming-Gen He, Hui Kai Sun, Yong-Guang Zheng, Ying Liu, An Luo, Han-Yi Wang, Zihang Zhu, Pei-Yue Qiu, Yingchao Shen, Xuan-Kai Wang, Wan Lin, Song-Tao Yu, Bin-Chen Li, Bo Xiao, Meng-Da Li, Yumeng Yang, Xiao Qiang Jiang, Han-Ning Dai, You Zhou, Xiongfeng Ma, Zhen-Sheng Yuan, Jian-Wei Pan

Published Aug 18, 2023• 35 citations

Abstract

Ultracold atoms in optical lattices form a competitive candidate for quantum computation owing to the excellent coherence properties, the highly parallel operations over spins, and the ultralow entropy achieved in qubit arrays. For this, a massive number of parallel entangled atom pairs have been realized in superlattices. However, the more formidable challenge is to scale up and detect multipartite entanglement, the basic resource for quantum computation, due to the lack of manipulations over local atomic spins in retroreflected bichromatic superlattices. In this Letter, we realize the functional building blocks in quantum-gate-based architecture by developing a cross-angle spin-dependent optical superlattice for implementing layers of quantum gates over moderately separated atoms incorporated with a quantum gas microscope for single-atom manipulation and detection. Bell states with a fidelity of 95.6(5)% and a lifetime of 2.20±0.13 s are prepared in parallel, and then connected to multipartite entangled states of one-dimensional ten-atom chains and two-dimensional plaquettes of 2×4 atoms. The multipartite entanglement is further verified with full bipartite nonseparability criteria. This offers a new platform toward scalable quantum computation and simulation.

DOI: 10.1103/physrevlett.131.073401

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We present a protocol to prepare decoherence-free cluster states using ultracold atoms loaded in a two dimensional superlattice. The superlattice geometry leads to an array of $2\ifmmode\times\else\texttimes\fi{}2$ plaquettes, each of them holding four spin-

1∕2

particles that can be used for encoding a single logical qubit in the twofold singlet subspace, insensitive to uniform magnetic field fluctuations in any direction. Dynamical manipulation of the supperlattice yields distinct inter- and intraplaquette interactions and permits us to realize one qubit and two qubit gates with high fidelity, leading to the generation of universal cluster states for measurement based quantum computation. Our proposal based on inter- and intraplaquette interactions also opens the path to study polymerized Hamiltonians which support ground states describing arbitrary quantum circuits.

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