How many qubits does it take to simulate an atomic nucleus?

Three different ways of encoding nuclear shell-model physics onto qubits were tested on IBM's quantum hardware for boron-10 and carbon-12. The best encoding nailed the boron-10 ground state energy to within 0.21% error after error mitigation — competitive with classical methods. The catch: carbon-12 was still 6.8% off, revealing how quickly quantum noise wins as nuclei get heavier.