Probing entanglement in a 2D hard-core Bose-Hubbard lattice.

Karamlou, Amir H; Rosen, Ilan T; Muschinske, Sarah E; Barrett, Cora N; Di Paolo, Agustin; Ding, Leon; Harrington, Patrick M; Hays, Max et al. · Nature · 2024

basic_science · Level V

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Abstract

Entanglement and its propagation are central to understanding many physical properties of quantum systems<sup>1-3</sup>. Notably, within closed quantum many-body systems, entanglement is believed to yield emergent thermodynamic behaviour<sup>4-7</sup>. However, a universal understanding remains challenging owing to the non-integrability and computational intractability of most large-scale quantum systems. Quantum hardware platforms provide a means to study the formation and scaling of entanglement in interacting many-body systems<sup>8-14</sup>. Here we use a controllable 4 × 4 array of superconducting qubits to emulate a 2D hard-core Bose-Hubbard (HCBH) lattice. We generate superposition states by simultaneously driving all lattice sites and extract correlation lengths and entanglement entropy across its many-body energy spectrum. We observe volume-law entanglement scaling for states at the centre of the spectrum and a crossover to the onset of area-law scaling near its edges.