Fig. 4: Multiqubit digitization of an arbitrary signal.

a Simulated probabilities of 1, 3, and 5 qubit digitizer when detecting a high dynamic range signal. b Simulated actual signal derived from the acquired phase (solid line), and average of 100 trials of a 1 qubit sensor output and 3bit classical ADC. c Experimentally and numerically determined Fisher information estimated for the case of the inverse Quantum Fourier Transform (QFT^†) sensing protocol, and the Standard Quantum Limit (SQL). Red dashed line marks a simulation of the QFT^† on the n-qubit circuit. Violet and green romb points are experimental results of the bare QFT^† algorithm and the QFT^† with sensing steps from data depicted in Fig. 2. n_q = 3.5 is used to express 2 qubits and 1 qutrit, resulting in 12 level quantum register. d The signal-to-noise of the sensor output as a function of (quantum) bits. Solid violet curve is deterministic classical ADC. The dashed lines represent the canonical SNR = 6.03 N_bits + C (db) of the classical ADC with noise and single (blue) and 16 trials of signal sampling. Solid read and green curves are quantum sensor with QPEA. Red - single trial of signal sampling, green—100 trials.