Quantum Sensing at the Edge: Precision Limits Near Dynamical Singularities
Dr Javid Naikoo, Joint Laboratory of Optics, Faculty of Science, Palacký University, Olomouc, Czech Republic

Singularities such as exceptional and hybrid exceptional-diabolic (HED) points naturally arise in the study of open quantum systems, where the interplay of loss and gain gives rise to rich and unconventional dynamical behaviour. In this talk, I will discuss how these singularities can be harnessed to achieve enhanced sensitivity in quantum sensing. Drawing on methods from quantum estimation theory and perturbative analysis of singular matrices, we examine how the sensitivity of a quantum system is governed by the structure of its response near these points. In particular, we show that operating at HED points can yield a twofold improvement in estimation precision compared to standard exceptional points. The analysis also identifies heterodyne detection as an optimal measurement strategy that achieves the fundamental quantum limit of precision. Overall, the results highlight how the unique features of open-system dynamics can be leveraged to develop ultrasensitive metrological protocols and advance next-generation quantum technologies.

References:
[1] Javid Naikoo, Ravindra W. Chhajlany, Janek Kołodynski, Phys. Rev. Lett.  131, 220801 (2023)
[2] Javid Naikoo, Ravindra W. Chhajlany, Adam Miranowicz, New J. Phys. 27 064505 (2025)