Gaussian quantum estimation of the loss parameter in a thermal environment

Robert Jonsson*, Roberto Di Candia

*Corresponding author for this work

Research output: Contribution to journalArticleScientificpeer-review

13 Citations (Scopus)
111 Downloads (Pure)


Lossy bosonic channels play an important role in a number of quantum information tasks, since they well approximate thermal dissipation in an experiment. Here, we characterize their metrological power in the idler-free and entanglement-assisted cases, using respectively single- and two-mode Gaussian states as probes. In the problem of estimating the loss parameter, we study the power-constrained quantum Fisher information (QFI) for generic temperature and loss parameter regimes, showing qualitative behaviours of the optimal probes. We show semi-analytically that the two-mode squeezed-vacuum state optimizes the QFI for any value of the loss parameter and temperature. We discuss the optimization of the total QFI, where the number of probes is allowed to vary by keeping the total power constrained. In this context, we elucidate the role of the ‘shadow-effect’, or passive signature, for reaching a quantum advantage. Finally, we discuss the implications of our results for the quantum illumination and quantum reading protocols.

Original languageEnglish
Article number385301
Number of pages35
JournalJournal of Physics A: Mathematical and Theoretical
Issue number38
Publication statusPublished - 23 Sept 2022
MoE publication typeA1 Journal article-refereed


  • Bosonic amplitude-damping channel
  • quantum Fisher information
  • quantum illumination
  • quantum metrology
  • quantum reading
  • quantum sensing


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