Cold-atom quantum sensing via Bayesian quantum estimation

Quantum sensors based on frequentist interferometry face a trade-off between sensitivity and dynamic range. Bayesian quantum estimation, combining Bayesian statistics with quantum metrology, can surpass the limit of conventional frequentist measurements. For cold-atom CPT clocks, our adaptive Bayesian protocol achieves Heisenberg-limited sensitivity in integration time and improves fractional frequency stability by 5.1(4) dB over conventional PID locking while enhancing robustness against technical noise [Phys. Rev. Applied 22, 044058 (2024)]. In CPT magnetometry, we optimize measurement sequences to improve precision scaling from T-0.5 to T-0.85. Using Bayesian quantum estimation to optimize the interferometry sequence, we yield a 145.6 nT dynamic range (14.6 dB higher than frequentist counterpart of 5.0 nT) with a sensitivity of 6.8 ± 0.1 pT/Hz¹/² (3.3 dB improvement over the frequentist counterpart of 14.7 ± 0.4 pT/Hz¹/²) [Science Advances 11, eadt3938 (2025)]. In addition to atomic clocks and magnetometers, this framework may bridge high sensitivity and broad dynamic range for other interferometry-based quantum sensors.