Certifying Non-Classicality and Non-Gaussianity Through Optical Parametric Amplification
Kalash M, Passos MH, Rácz É, Ruppert L, Filip R, Chekhova MV (2026)
Publication Type: Journal article
Publication year: 2026
Journal
Book Volume: 7
Article Number: 033020
Journal Issue: 3
DOI: 10.1103/J68X-SKMN
Abstract
Non-Gaussian states of light are essential for numerous quantum information protocols; thus, certifying non-Gaussianity (NG) is crucial. Full quantum state tomography, commonly used for this purpose, is complicated and yields inconclusive results for strongly mixed states. Certifying NG through directly measurable parameters is a simpler alternative, typically achieved by measuring photon-number probabilities—either directly, using photon-number resolving detectors, or through Hanbury Brown-Twiss type measurements with single-photon detectors. Here, we demonstrate, theoretically and experimentally, that phase-sensitive optical parametric amplification (OPA), followed by conventional intensity detection, can effectively replace this approach. Our proposed witness relies on the mean photon number (relative to that produced by the amplifier without any input) and the second-order correlation function after OPA. Both can be directly obtained from the measured amplified intensity and are invariant to detection losses. The method therefore requires neither photon-number resolution nor high detection efficiency. In a proof-of-principle experiment, we successfully certify the quantum NG of a heralded quasi-single-photon state. Since OPA is a broadband and multimode process, our method provides a foundation for developing high-dimensional quantum technologies utilizing broadband multimode non-Gaussian states.
Authors with CRIS profile
Involved external institutions
Max-Planck-Institut für die Physik des Lichts (MPL) / Max Planck Institute for the Science of Light
Germany (DE)
Palacky University Olomouc / Univerzita Palackého v Olomouci
Czech Republic (CZ)
Germany (DE)
Palacky University Olomouc / Univerzita Palackého v Olomouci
Czech Republic (CZ)
How to cite
APA:
Kalash, M., Passos, M.H., Rácz, É., Ruppert, L., Filip, R., & Chekhova, M.V. (2026). Certifying Non-Classicality and Non-Gaussianity Through Optical Parametric Amplification. PRX Quantum, 7(3). https://doi.org/10.1103/J68X-SKMN
MLA:
Kalash, Mahmoud, et al. "Certifying Non-Classicality and Non-Gaussianity Through Optical Parametric Amplification." PRX Quantum 7.3 (2026).
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