@article{66740,
  abstract     = {{<jats:title>Abstract</jats:title>
                  <jats:p>
                    We theoretically compare the quantum Fisher information (QFI) for three configurations of absorption spectroscopy with undetected idler photons: an SU(1,1) interferometer with inter-source idler loss, an induced-coherence (IC) setup in which the idler partially seeds a second squeezer together with a vacuum ancilla, and a distributed-loss (DL) scheme with in-medium attenuation. We calculate the QFI as a function of parametric gain for both full and signal-only detection access. For losses below 99% and low to moderate gain, the SU(1,1) configuration provides the largest QFI. At high gain and intermediate loss, the IC scheme performs best, while under extreme attenuation (transmission
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                    1%) the DL model becomes optimal. These results delineate the measurement regimes in which each architecture is optimal in terms of information theory.
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  author       = {{Houde, Martin and Roeder, Franz and Silberhorn, Christine and Brecht, Benjamin and Quesada, Nicolás}},
  issn         = {{2515-7647}},
  journal      = {{Journal of Physics: Photonics}},
  number       = {{3}},
  publisher    = {{IOP Publishing}},
  title        = {{{Quantum fisher information analysis for absorption measurements with undetected photons}}},
  doi          = {{10.1088/2515-7647/ae82a2}},
  volume       = {{8}},
  year         = {{2026}},
}