High-Visibility Franson Interference Enabled by Passive Photonic Integrated Interferometers at Telecom Wavelengths

Quantum Physics [Submitted on 27 Mar 2026] High-Visibility Franson Interference Enabled by Passive Photonic Integrated Interferometers at Telecom Wavelengths Ramin Emadi, Domenico Ribezzo, Giulia Guarda, Davide Bacco, Alessandro Zavatta High-visibility Franson interference at telecom C-band wavelengths is achieved using a cascaded periodically poled lithium niobate (PPLN) waveguide photon-pair source combined with fully passive, path-imbalanced Mach-Zehnder interferometers implemented on photonic integrated circuits (PICs). The interferometers require neither on-chip phase shifters nor active stabilization; instead, the phase is scanned via thermal tuning of the chip. By employing a narrow-linewidth continuous-wave (CW) pump and dense wavelength-division multiplexing (DWDM) filtering, energy-time entangled photon pairs with high spectral indistinguishability are generated. We achieve a 4.8% heralding efficiency and a two-photon interference visibility of 97.1% from sinusoidal fringe fitting (raw visibility 95.2% and background-corrected visibility 95.6%), alongside a coincidence-to-accidental ratio (CAR) exceeding 1000 at only 1.7 mW of pump power. These results represent one of the highest Franson-interference visibilities reported for a PIC-based analyzer within a compact, fiber-integrated platform. Subjects: Quantum Physics (quant-ph) Cite as: arXiv:2603.26355 [quant-ph]   (or arXiv:2603.26355v1 [quant-ph] for this version)   https://doi.org/10.48550/arXiv.2603.26355 Focus to learn more Submission history From: Ramin Emadi [view email] [v1] Fri, 27 Mar 2026 12:27:26 UTC (256 KB) Access Paper: HTML (experimental) view license Current browse context: quant-ph < prev   |   next > new | recent | 2026-03 References & Citations INSPIRE HEP NASA ADS Google Scholar Semantic Scholar Export BibTeX Citation Bookmark Bibliographic Tools Bibliographic and Citation Tools Bibliographic Explorer Toggle Bibliographic Explorer (What is the Explorer?) Connected Papers Toggle Connected Papers (What is Connected Papers?) Litmaps Toggle Litmaps (What is Litmaps?) scite.ai Toggle scite Smart Citations (What are Smart Citations?) Code, Data, Media Demos Related Papers About arXivLabs Which authors of this paper are endorsers? | Disable MathJax (What is MathJax?)