Quantum Computer Recreates Particle Collisions That Turn Energy Into Matter

In the first instants after two high-energy particles slam into each other, something remarkable can happen: the kinetic energy of the collision transforms into entirely new particles that did not exist before the impact. This process, known as inelastic particle production, is one of the most fundamental consequences of quantum field theory and underlies what happens in particle colliders and in the hot, dense universe moments after the Big Bang. Yet simulating such out-of-equilibrium collisions on ordinary computers is extraordinarily difficult, because the entanglement and complexity of the quantum states involved grow explosively with system size and time. Now, a team of researchers has reported evidence of inelastic particle production in a quantum field theory using a digital quantum processor, running a simulation on 104 qubits and opening a practical route toward studying real-time scattering dynamics that have long been beyond the reach of classical computation.

The work, published in Nature Physics by Roland C. Farrell and John Preskill of the California Institute of Technology along with Nikita A. Zemlevskiy and Marc Illa of the University of Washington, focuses on the one-dimensional Ising field theory, a simplified but physically rich model of interacting particles. The team collided two wavepackets, each carrying the lightest particle in the theory, and watched what emerged after the crash. By measuring the skewness of the energy density left behind in the collision region, they identified an inelastic component of the outgoing radiation: a final state containing one light particle alongside one heavier particle, a configuration that could only arise if collision energy had been converted into new matter. The experiment used up to 5,589 two-qubit gates to access the post-collision dynamics, making it one of the deepest quantum simulations of scattering reported to date.