article published Martin Houde author Franz Roeder author 88149 Christine Silberhorn author 26263 Benjamin Brecht author 271500000-0003-4140-0556 Nicolás Quesada author 15 department 623 department 288 department <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 <jats:inline-formula> <jats:tex-math> </jats:tex-math> <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> <mml:mrow> <mml:mo>&lt;</mml:mo> </mml:mrow> </mml:math> </jats:inline-formula> 1%) the DL model becomes optimal. These results delineate the measurement regimes in which each architecture is optimal in terms of information theory. </jats:p> IOP Publishing2026 eng 2515-764710.1088/2515-7647/ae82a2 83 M. Houde, F. Roeder, C. Silberhorn, B. Brecht, and N. Quesada, “Quantum fisher information analysis for absorption measurements with undetected photons,” <i>Journal of Physics: Photonics</i>, vol. 8, no. 3, Art. no. 035013, 2026, doi: <a href="https://doi.org/10.1088/2515-7647/ae82a2">10.1088/2515-7647/ae82a2</a>. Houde, M., Roeder, F., Silberhorn, C., Brecht, B., &#38; Quesada, N. (2026). Quantum fisher information analysis for absorption measurements with undetected photons. <i>Journal of Physics: Photonics</i>, <i>8</i>(3), Article 035013. <a href="https://doi.org/10.1088/2515-7647/ae82a2">https://doi.org/10.1088/2515-7647/ae82a2</a> Houde, Martin, Franz Roeder, Christine Silberhorn, Benjamin Brecht, and Nicolás Quesada. “Quantum Fisher Information Analysis for Absorption Measurements with Undetected Photons.” <i>Journal of Physics: Photonics</i> 8, no. 3 (2026). <a href="https://doi.org/10.1088/2515-7647/ae82a2">https://doi.org/10.1088/2515-7647/ae82a2</a>. M. Houde, F. Roeder, C. Silberhorn, B. Brecht, N. Quesada, Journal of Physics: Photonics 8 (2026). Houde, Martin, et al. “Quantum Fisher Information Analysis for Absorption Measurements with Undetected Photons.” <i>Journal of Physics: Photonics</i>, vol. 8, no. 3, 035013, IOP Publishing, 2026, doi:<a href="https://doi.org/10.1088/2515-7647/ae82a2">10.1088/2515-7647/ae82a2</a>. @article{Houde_Roeder_Silberhorn_Brecht_Quesada_2026, title={Quantum fisher information analysis for absorption measurements with undetected photons}, volume={8}, DOI={<a href="https://doi.org/10.1088/2515-7647/ae82a2">10.1088/2515-7647/ae82a2</a>}, number={3035013}, journal={Journal of Physics: Photonics}, publisher={IOP Publishing}, author={Houde, Martin and Roeder, Franz and Silberhorn, Christine and Brecht, Benjamin and Quesada, Nicolás}, year={2026} } Houde M, Roeder F, Silberhorn C, Brecht B, Quesada N. Quantum fisher information analysis for absorption measurements with undetected photons. <i>Journal of Physics: Photonics</i>. 2026;8(3). doi:<a href="https://doi.org/10.1088/2515-7647/ae82a2">10.1088/2515-7647/ae82a2</a> 667402026-08-18T10:20:21Z2026-08-18T10:20:54Z