Geometric Breaking of Quantum Strings in Kagome Rydberg Atom Array

Abstract: Leveraging the rapid development of quantum simulators, the intriguing phenomena of string breaking are observed across various quantum simulation platforms \cite{Rydberg_kagome,qbit_string_breaking}. However, the strings can only be broken by quenching the tension energy due to the system size limitation, such "tensile breaking" behaves quite the same as in one-dimension \cite{ion_string_breaking}. To discover the distinctive properties of quantum strings in two dimensions, we utilize a newly developed quantum Monte Carlo method to simulate a ten times larger scale (743-site) Kagome Rydberg atom array which can be described with U(1) lattice gauge theory. With designed edges, one end of the string can be easily grasped, allowing for clearly observing the dynamics of the dangling gauge charge at the open end. Then, we can drag each end in opposite directions perpendicular to the string. As the separation distance increases, asymptotic freedom-like behavior is detected. Eventually, the string breaks because the distance between both ends surpasses the string's length, so named "geometric breaking". Distinct from "tensile breaking," the two newly formed strings are suddenly uncorrelated, accompanied by a sudden energy increase. Lastly, we study multiple strings and successfully prepare a heart-like superposition state of broken and unbroken quantum strings with three gauge charges attached reminiscent of quarks and gluon. This work can benefit the comprehension of quantum strings and also shed light on the simulation of high-energy physics.