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String-Breaking Dynamics in Quantum Adiabatic and Diabatic Processes

Federica Maria Surace1,*, Alessio Lerose2,3, Or Katz4,5, Elizabeth R. Bennewitz6,7, Alexander Schuckert6,7, De Luo4, Arinjoy De4,7, Brayden Ware6,7, William Morong6,7,† et al.

Kate Collins6,7, Christopher Monroe4, Zohreh Davoudi6,8, and Alexey V. Gorshkov6,7

  • *Contact author: Federica.Surace@uibk.ac.at
  • †Present address: AWS Center for Quantum Computing, Pasadena, California 91125, USA. Work done prior to joining AWS.
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PRX Quantum 7, 020331 – Published 18 May, 2026

DOI: https://doi.org/10.1103/c4zd-lbyq

Abstract

Confinement prohibits isolation of color charges, e.g., quarks, in nature via a process called string breaking: the separation of two charges results in an increase in the energy of a color flux, visualized as a string, connecting those charges. Eventually, creating additional charges is energetically favored, hence breaking the string. Such a phenomenon can be probed in simpler models, including quantum spin chains, enabling enhanced understanding of string-breaking dynamics. A challenging task is to understand how string breaking occurs as time elapses, in an out-of-equilibrium setting. This work establishes the phenomenology of dynamical string breaking induced by a gradual increase of string tension over time. It, thus, goes beyond instantaneous quench processes and enables tracking the real-time evolution of strings in a more controlled setting. We focus on domain-wall confinement in a family of quantum Ising chains. Our results indicate that, for sufficiently short strings and slow evolution, string breaking can be described by the transition dynamics of a two-state quantum system akin to a Landau-Zener process. For longer strings, a more intricate spatiotemporal pattern emerges: the string breaks by forming a superposition of bubbles (domains of flipped spins of varying sizes), which involve highly excited states. We finally demonstrate that string breaking driven only by quantum fluctuations can be realized in the presence of sufficiently long-ranged interactions. This work holds immediate relevance for studying string breaking in quantum-simulation experiments.

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Popular Summary

In physics, confinement means that certain particles, like quarks, can never exist in isolation. They are bound by a “string” whose tension grows as you pull them apart. Rather than stretching indefinitely, the system eventually creates a new particle pair from empty space, snapping the string. This process is known as string breaking.

Instead of high-energy experiments, we studied this effect in a simpler, controllable setting: a quantum spin chain. By gradually increasing the string tension, we could watch the process unfold in real time. For short strings, the system shows a sharp jump from “stretched” to “broken.” For longer strings, however, it enters a more complex quantum regime, forming a superposition in which broken and unbroken segments coexist and fluctuate.

This work opens a practical route to studying string breaking in quantum simulators and has already inspired experiments observing it in trapped-ion systems.

Article Text

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PRX Quantum 7, 020331– Published 18 May, 2026
  • Received 24 January 2025
  • Revised 20 November 2025
  • Accepted 16 March 2026
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