We present a framework for efficiently preparing meson wave packets for a lattice gauge theory on quantum devices. The method is demonstrated using a (1+1)D Z2 lattice gauge theory coupled to Kogut-Susskind staggered fermions as a testbed. Our approach systematically constructs mesonic excitations on top of the ground state with well-defined momentum. Using a quantum subspace expansion approach with a symmetry-preserving basis, we obtain explicit operators for creating such excitations, which in turn allow us to construct localized wave packets. By simulating the scattering process of two meson wave packets with Tensor Network States, we identify both elastic and inelastic scattering processes during the dynamics. In addition, we also provide a resource-efficient decomposition for the operators creating mesonic wave packets into elementary quantum gates, thus enabling quantum simulation of meson scattering in the (1+1)D Z2 lattice gauge theory.
Simulating Meson Scattering in (1+1)D Z2 Lattice Gauge Theory: Efficient Operator Construction and Quantum Circuit Implementation
We present a framework for efficiently preparing meson wave packets for a lattice gauge theory on quantum devices. The method is demonstrated using a (1+1)D Z2 lattice gauge theory coupled to Kogut-Susskind staggered fermions as a testbed. Our approach systematically constructs mesonic excitations on top of the ground state with well-defined momentum. Using a quantum subspace expansion approach with a symmetry-preserving basis, we obtain explicit operators for creating such excitations, which in turn allow us to construct localized wave packets. By simulating the scattering process of two meson wave packets with Tensor Network States, we identify both elastic and inelastic scattering processes during the dynamics. In addition, we also provide a resource-efficient decomposition for the operators creating mesonic wave packets into elementary quantum gates, thus enabling quantum simulation of meson scattering in the (1+1)D Z2 lattice gauge theory.
We present a framework for efficiently preparing meson wave packets for a lattice gauge theory on quantum devices. The method is demonstrated using a (1+1)D Z2 lattice gauge theory coupled to Kogut-Susskind staggered fermions as a testbed. Our approach systematically constructs mesonic excitations on top of the ground state with well-defined momentum. Using a quantum subspace expansion approach with a symmetry-preserving basis, we obtain explicit operators for creating such excitations, which in turn allow us to construct localized wave packets. By simulating the scattering process of two meson wave packets with Tensor Network States, we identify both elastic and inelastic scattering processes during the dynamics. In addition, we also provide a resource-efficient decomposition for the operators creating mesonic wave packets into elementary quantum gates, thus enabling quantum simulation of meson scattering in the (1+1)D Z2 lattice gauge theory.
Scattering processes are essential for understanding the structure of matter, yet their real-time dynamics remain challenging to simulate classically. Quantum computers offer a promising path toward efficient simulation of such physical systems. Here, we present a general and scalable framework for simulating meson scattering in lattice gauge theories on digital quantum hardware. Our approach addresses two key challenges: First, we introduce a symmetry-preserving quantum subspace expansion method for constructing high-fidelity meson creation operators across a wide range of coupling and momenta. Second, we design a quantum circuit for meson wave packet preparation using Givens rotations, improving accuracy while reducing circuit depth compared to existing approaches. We demonstrate the method in a ( 1 + 1 )-dimensional Z 2 gauge theory and explore meson scattering dynamics with tensor network simulations. We study both elastic and inelastic scattering and provide a comprehensive characterization of the scattering process in terms of energy transfer, entanglement entropy, and heavier particle production during the dynamics. Our work provides a scalable, nonvariational approach for simulating meson scattering on near-term quantum devices and offers a concrete strategy for probing nonperturbative dynamics in confining gauge theories.
Quantum simulation holds promise of enabling a complete description of high-energy scattering processes rooted in gauge theories of the Standard Model. A first step in such simulations is preparation of interacting hadronic wave packets. To create the wave packets, one typically resorts to adiabatic evolution to bridge between wave packets in the free theory and those in the interacting theory, rendering the simulation resource intensive. In this work, we construct a wave-packet creation operator directly in the interacting theory to circumvent adiabatic evolution, taking advantage of resource-efficient schemes for ground-state preparation, such as variational quantum eigensolvers. By means of an ansatz for bound mesonic excitations in confining gauge theories, which is subsequently optimized using classical or quantum methods, we show that interacting mesonic wave packets can be created efficiently and accurately using digital quantum algorithms that we develop. Specifically, we obtain high-fidelity mesonic wave packets in the Z 2 and U ( 1 ) lattice gauge theories coupled to fermionic matter in 1+1 dimensions. Our method is applicable to both perturbative and non-perturbative regimes of couplings. The wave-packet creation circuit for the case of the Z 2 lattice gauge theory is built and implemented on the Quantinuum H1-1 trapped-ion quantum computer using 13 qubits and up to 308 entangling gates. The fidelities agree well with classical benchmark calculations after employing a simple symmetry-based noise-mitigation technique. This work serves as a step toward quantum computing scattering processes in quantum chromodynamics.
We present a first real-time study of hadronic scattering in a (1+1)-dimensional SU(2) lattice gauge theory with fundamental fermions using tensor-network techniques. Working in the gaugeless Hamiltonian formulation, we investigate scattering processes across sectors of fixed global baryon number B=0,1,2, corresponding respectively to meson--meson, meson--baryon, and baryon--baryon collisions. At strong coupling, the B=0 and B=2 channels exhibit predominantly elastic dynamics closely resembling the U(1) Schwinger model. The mixed B=1 sector displays qualitatively new behavior: meson and baryon wavepackets become entangled during the collision, with the slower state becoming spatially delocalized while the faster one propagates ballistically. We characterize these processes through local observables, entanglement entropy, and the information lattice.
We present a digital quantum computation of two-hadron scattering in a Z2 lattice gauge theory in 1+1 dimensions. We prepare well-separated single-particle wave packets with desired momentum-space wavefunctions, and simulate their collision through digitized time evolution. Multiple hadronic wave packets can be produced using the efficient, systematically improvable algorithm of this work, achieving high fidelity with the target initial state. Specifically, employing a trapped-ion quantum computer (IonQ Forte), we prepare up to three meson wave packets using 11 and 27 system qubits, and simulate collision dynamics of two meson wave packets for the smaller system. Results for local observables are consistent with numerical simulations at early times, but decoherence effects limit evolution into long times. We demonstrate the critical role of high-fidelity initial states for precision measurements of state-sensitive observables, such as S-matrix elements. Our work establishes the potential of quantum computers in simulating hadron-scattering processes in strongly interacting gauge theories.
With the aim of studying nonperturbative out-of-equilibrium dynamics of high-energy particle collisions on quantum simulators, we investigate the scattering dynamics of lattice quantum electrodynamics in 1+1 dimensions. Working in the bosonized formulation of the model and in the thermodynamic limit, we use uniform-matrix-product-state tensor networks to construct multiparticle wave-packet states, evolve them in time, and detect outgoing particles post collision. This facilitates the numerical simulation of scattering experiments in both confined and deconfined regimes of the model at different energies, giving rise to rich phenomenology, including inelastic production of quark and meson states, meson disintegration, and dynamical string formation and breaking. We obtain elastic and inelastic scattering cross sections, together with time-resolved momentum and position distributions of the outgoing particles. Furthermore, we propose an analog circuit-QED implementation of the scattering process that is native to the platform, requires minimal ingredients and approximations, and enables practical schemes for particle wave-packet preparation and evolution. This study highlights the role of classical and quantum simulation in enhancing our understanding of scattering processes in quantum field theories in real time.