# quantum-classical crossover

Judging where quantum dynamics simulation wins depends on two method portfolios that keep moving, so a crossover fixed in a single paper ages quickly. QSim-Arena turns that assessment into a closed loop maintained by AI agents: agents convert published techniques into executable components, admit a method only after it reproduces a published number, and have results checked by a lane that did not produce them. Starting from the fault-tolerant crossover route of Sun et al., agents introduced three published techniques within a week, lowering certified runtime on four Hamiltonian families at sixteen qubits (twelve for the hydrogen chain) by factors of 21, 23, 25 and 185, and measured runtime fourfold on every family.

Judging where quantum dynamics simulation wins depends on two method portfolios that keep moving, so a crossover fixed in a single paper ages quickly. QSim-Arena turns that assessment into a closed loop maintained by AI agents: agents convert published techniques into executable components, admit a method only after it reproduces a published number, and have results checked by a lane that did not produce them. Starting from the fault-tolerant crossover route of Sun et al., agents introduced three published techniques within a week, lowering certified runtime on four Hamiltonian families at sixteen qubits (twelve for the hydrogen chain) by factors of 21, 23, 25 and 185, and measured runtime fourfold on every family.