Accurate parameter estimation is a central task in quantum metrology and sensing, where quantum resources can provide precision beyond classical limits. In realistic settings, however, system-environment interactions lead to decoherence, reducing these strategies to their classical counterparts. Noise is typically classified as Markovian or non-Markovian, with the latter often preserving quantum coherence longer and thus supporting better metrological performance. Still, the absence of noise is generally considered ideal. In this work, we demonstrate that selectively engineered non-Markovian dynamics can outperform both the Markovian dynamics—including the corresponding quantum Cramér-Rao bounds—and the entirely noiseless case, corresponding to dispersion-free limit. We demonstrate these findings numerically for an all-optical setup, which is experimentally feasible and can be extended to other physical platforms. In general, our results open avenues for noise-assisted quantum metrology beyond conventional limits.

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• Open quantum systems & decoherence
• Quantum information theory
• Quantum optics
• Quantum parameter estimation