Abstract
The study of confinement in quantum spin chains has seen a large surge of interest in recent years. It is not only important for understanding a range of effective one-dimensional condensed-matter realizations but it also shares some of the nonperturbative physics with quantum chromodynamics (QCD), which makes it a prime target for current quantum simulation efforts. In analogy to QCD, the confinement-induced two-particle bound states that appear in these models are dubbed mesons. Here, we study scattering events due to meson collisions in a quantum spin chain with long-range interactions such that two mesons have an extended interaction. We show how novel hadronic bound states, e.g., with four constituent particles akin to tetraquarks, may form dynamically in fusion events. In a natural collision their signal is weak, as elastic meson scattering dominates. However, we propose two controllable protocols that allow for a clear observation of dynamical hadron formation. We discuss how this physics can be simulated in trapped-ion or Rydberg-atom setups.
- Received 12 April 2022
- Revised 2 August 2022
- Accepted 15 September 2022
DOI:https://doi.org/10.1103/PRXQuantum.3.040309
Published by the American Physical Society under the terms of the Creative Commons Attribution 4.0 International license. Further distribution of this work must maintain attribution to the author(s) and the published article's title, journal citation, and DOI.
Published by the American Physical Society
Physics Subject Headings (PhySH)
Popular Summary
This article explores how to emulate elementary particle scattering experiments in quantum simulators. In this work, we consider the long-range transverse field Ising model, which is known to exhibit confinement of the elementary domain-wall excitations into mesonic bound states. We show that the long-range interactions not only lead to mesonic excitations, but also bound states of two mesons, akin to tetraquarks. Furthermore, we demonstrate how a metastable tetraquark can form dynamically in a collision—a simplified “fusion” event.
To establish that true bound states of two mesons exist in the long-ranged Ising model, we consider the energy eigenvalues of a four-domain-wall subspace Hamiltonian. From this, clear tetraquark bound states are visible. However, as these bound states are orthogonal to any initial state of freely propagating mesons, when considering the dynamical formation of tetraquarks, we are relegated to considering metastable tetraquarks. Nonetheless, we present a subtle signature of metastable tetraquark formation in meson collisions. While these results are exciting, the protocol to obtain them was somewhat unstructured. Thus, we propose two controllable protocols that allow for a much clearer observation of these fusion events in a controllable manner. Furthermore, our methods are discussed in the context of experimental feasibility.
Not only would the experimental realizations of these results be a huge benchmark for current quantum devices, but with the simulation of the fundamental interactions between particles being a huge challenge, such experiments would act as the first step toward simulating similar particle scattering events in quantum chromodynamics.
