Optimized heteronuclear-ion quantum demodulator with inverse-quartic and inverse-quadratic temporal scalings

Efficient and precise measurement of electromagnetic signals is crucial for both fundamental science and practical applications. Demodulation is a widely used technique for receiving and recovering modulated signals. Here we show a quantum demodulator using two heteronuclear ions to simultaneously detect the amplitudes and frequencies of unknown periodic signals, overcoming the constraint of double-parameter optimization. With reinforcement learning, the quantum Fisher information scales as t4 f