---
res:
  bibo_abstract:
  - Multimode quantum light has promising applications in many areas of physics, such
    as quantum communications and quantum computing. However, its multimode nature
    also makes it challenging to measure its properties. Recently [I. Barakat et al.,
    Optica Quantum 3, 36 (2025)], a technique for the simultaneous measurement of
    squeezing of multiple broadband modes based on a phase-sensitive amplification
    approach was experimentally implemented using a setup that effectively corresponds
    to an SU(1,1) interferometer. Here, we aim to provide a complete theoretical analysis
    of the modal structure of (generally unbalanced) SU(1,1) interferometers and a
    detailed theoretical formal derivation of the framework for this technique. Utilizing
    the joint Schmidt decomposition of the transfer functions, we investigate the
    shape and phase profiles of the modes of the SU(1,1) interferometer and its components
    [parametric down-conversion (PDC) sections] for different parametric gain regimes.
    We discover a complicated interplay between the PDC modes and the modes of the
    entire interferometer, and analyze it by using their overlap coefficients as a
    similarity measure. Finally, we develop a rigorous processing method for the aforementioned
    multimode squeezing measurement technique and discuss necessary approximations
    to make this method experimentally feasible.@eng
  bibo_authorlist:
  - foaf_Person:
      foaf_givenName: Dennis
      foaf_name: Scharwald, Dennis
      foaf_surname: Scharwald
      foaf_workInfoHomepage: http://www.librecat.org/personId=55907
    orcid: 0009-0007-5654-5412
  - foaf_Person:
      foaf_givenName: Polina
      foaf_name: Sharapova, Polina
      foaf_surname: Sharapova
      foaf_workInfoHomepage: http://www.librecat.org/personId=60286
  bibo_doi: 10.1103/ph64-ts39
  bibo_issue: '3'
  bibo_volume: 8
  dct_date: 2026^xs_gYear
  dct_isPartOf:
  - http://id.crossref.org/issn/2643-1564
  dct_language: eng
  dct_publisher: American Physical Society (APS)@
  dct_title: Characterization of spatial Schmidt modes in high-gain SU(1,1) interferometers@
...