Optimal Gaussian metrology for generic multimode interferometric circuit

Teruo Matsubara, Paolo Facchi, Vittorio Giovannetti, Kazuya Yuasa*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

20 Citations (Scopus)


Bounds on the ultimate precision attainable in the estimation of a parameter in Gaussian quantum metrology are obtained when the average number of bosonic probes is fixed. We identify the optimal input probe state among generic (mixed in general) Gaussian states with a fixed average number of probe photons for the estimation of a parameter contained in a generic multimode interferometric optical circuit, namely, a passive linear circuit preserving the total number of photons. The optimal Gaussian input state is essentially a single-mode squeezed vacuum, and the ultimate precision is achieved by a homodyne measurement on the single mode. We also reveal the best strategy for the estimation when we are given L identical target circuits and are allowed to apply passive linear controls in between with an arbitrary number of ancilla modes introduced.

Original languageEnglish
Article number033014
JournalNew Journal of Physics
Issue number3
Publication statusPublished - 2019 Mar 19


  • Gaussian states
  • optical circuits
  • quantum Fisher information
  • quantum estimation
  • quantum metrology
  • squeezed states

ASJC Scopus subject areas

  • Physics and Astronomy(all)


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