Observation of genuine $2+1$D string dynamics in a U$(1)$ lattice gauge theory with a tunable plaquette term on a trapped-ion quantum computer

Quantum Physics [Submitted on 8 Apr 2026] Observation of genuine 2+1D string dynamics in a U(1) lattice gauge theory with a tunable plaquette term on a trapped-ion quantum computer Rohan Joshi, Yizhuo Tian, Kevin Hemery, N. S. Srivatsa, Jesse J. Osborne, Henrik Dreyer, Enrico Rinaldi, Jad C. Halimeh Quantum simulations of high-energy physics in 2+1D can probe dynamical phenomena nonexistent in one spatial dimension and access regimes that are challenging for existing classical simulation methods. For string dynamics -- relevant to hadronization -- a plaquette term is required to realize genuine 2+1D behavior, as it endows the gauge field with dynamics and enables the propagation of photon-like excitations. Here, we realize a U(1) quantum link model of quantum electrodynamics in two spatial dimensions with a tunable plaquette term on a \texttt{Quantinuum System Model H2} quantum computer. We implement, to our knowledge, the largest quantum simulation of string-breaking dynamics reported to date, on a 5 \times 4 matter-site square lattice using 51 qubits. The simulation uses a shallow circuit design with a two-qubit gate depth of 28 per Trotter step and up to 1540 entangling gates. Starting from far-from-equilibrium string configurations, we measure the probability for the string to propagate within the lattice plane and find signatures of genuine 2+1D dynamics only when the plaquette term is present. In a resonant regime, we observe the annihilation of string segments accompanied by the production of electron--positron pairs that screen them. We further find that, only with a nonzero plaquette term, matter creation extends across the lattice plane rather than remaining confined to the initial string path. These results experimentally realize string breaking and demonstrate the emergence of dynamical gauge fields in two spatial dimensions, establishing a route to photon-like propagation in programmable quantum simulators of gauge theories. Comments: 12+13 pages, 4+12 figures, 0+1 table. See parallel submission by K. Xu et al., "Observation of glueball excitations and string breaking in a 2+1D \mathbb{Z}_2 lattice gauge theory on a trapped-ion quantum computer'' Subjects: Quantum Physics (quant-ph); Quantum Gases (cond-mat.quant-gas); Strongly Correlated Electrons (cond-mat.str-el); High Energy Physics - Lattice (hep-lat); High Energy Physics - Theory (hep-th) Cite as: arXiv:2604.07436 [quant-ph]   (or arXiv:2604.07436v1 [quant-ph] for this version)   https://doi.org/10.48550/arXiv.2604.07436 Focus to learn more Submission history From: Jad C. Halimeh [view email] [v1] Wed, 8 Apr 2026 18:00:00 UTC (1,902 KB) Access Paper: view license Current browse context: quant-ph < prev   |   next > new | recent | 2026-04 Change to browse by: cond-mat cond-mat.quant-gas cond-mat.str-el hep-lat hep-th References & Citations INSPIRE HEP NASA ADS Google Scholar Semantic Scholar Export BibTeX Citation Bookmark Bibliographic Tools Bibliographic and Citation Tools Bibliographic Explorer Toggle Bibliographic Explorer (What is the Explorer?) Connected Papers Toggle Connected Papers (What is Connected Papers?) Litmaps Toggle Litmaps (What is Litmaps?) scite.ai Toggle scite Smart Citations (What are Smart Citations?) Code, Data, Media Demos Related Papers About arXivLabs Which authors of this paper are endorsers? | Disable MathJax (What is MathJax?)