Superconducting-antiqubit simulation enables optimal phase estimation via unitary inversion
The research simulates antimatter using 'antiqubits'—transmon superconducting qubits with a negative gyromagnetic ratio—to enable platform-specific unitary inversion. This technique, combined with qubit-antiqubit entanglement, achieves the theoretical maximum quantum advantage in phase estimation (Fisher Information of 4), surpassing all other strategies for sensing unknown field directions.