LPHYS'26
34th Annual International Laser Physics Conference

Quantum Metrology for Open Systems

L Davidovich1,2

1 Federal University of Rio de Janeiro, Rio de Janeiro, Brazil
2 Institute for Quantum Science and Engineering (IQSE), Texas A&M University, College Station TX, USA

Seminar: Pl — Plenary Session

Monday, 6 July 2026 · 09:40 – 10:20

Abstract

Quantum sensors are employed to estimate parameters with higher precision than classical sensors. For noiseless systems, the Cramér–Rao bound, which links estimation uncertainty to Fisher information, serves as a useful benchmark. Extending this bound to open systems has been proposed and applied to several key systems [1–4], a relevant generalization considering the widespread presence of the environment. Entanglement can then play a crucial role despite its fragility [5,6]. Interestingly, when the estimated parameter pertains to noise itself [7–9], the vulnerability of entanglement may actually enhance precision [8]. This talk reviews recent advances in this area, resulting in precision bounds for noisy systems, with applications such as estimating light absorption and depolarization.

References

  1. B M Escher, R L de Matos Filho and L Davidovich, Nat. Phys. 7, 406 (2011); DOI: 10.1038/nphys1958
  2. B M Escher, L Davidovich, N Zagury and R L de Matos Filho, Phys. Rev. Lett. 109, 190404 (2012); DOI: 10.1103/PhysRevLett.109.190404
  3. M M Taddei, B M Escher, L Davidovich and R L de Matos Filho, Phys. Rev. Lett. 110, 050402 (2013); DOI: 10.1103/PhysRevLett.110.050402
  4. C L Latune, B M Escher, R L de Matos Filho and L Davidovich, Phys. Rev. A 88, 042112 (2013); DOI: 10.1103/PhysRevA.88.042112
  5. M P Almeida, F de Melo, M Hor-Meyll, A Salles, S P Walborn, P H Souto Ribeiro and L Davidovich, Science 316, 579 (2007); DOI: 10.1126/science.1139892
  6. L Aolita, R Chaves, D Cavalcanti, A Acín and L Davidovich, Phys. Rev. Lett. 100, 080501 (2008); DOI: 10.1103/PhysRevLett.100.080501
  7. J Wang, L Davidovich and G S Agarwal, Phys. Rev. Res. 2, 033389 (2020); DOI: 10.1103/PhysRevResearch.2.033389
  8. L Davidovich and R L de Matos Filho, Phys. Rev. A 108, 042612 (2023); DOI: 10.1103/PhysRevA.108.042612
  9. J Wang, R L de Matos Filho, G S Agarwal and L Davidovich, Phys. Rev. Res. 6, 013034 (2024); DOI: 10.1103/PhysRevResearch.6.013034
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