Optimised spectral purity of unfiltered photons via pump and nonlinearity shaping

• URL: http://arxiv.org/abs/2510.06196v1
• Date: Tue, 07 Oct 2025 17:52:16 GMT
• Title: Optimised spectral purity of unfiltered photons via pump and nonlinearity shaping
• Abstract summary: Photonic quantum technologies rely on efficient generation and interference of indistinguishable photons.<n>We show high two-photon interference using only moderate bandpass spectral filtering.
• Score: 31.576375158481827
• License: http://creativecommons.org/licenses/by/4.0/
• Abstract: Photonic quantum technologies rely on the efficient generation and interference of indistinguishable photons. Exceptional achievements in this respect have been obtained by domain engineering of quasi-phase-matched parametric down-conversion sources, demonstrating high two-photon interference visibility using only moderate bandpass spectral filtering. Here, we optimised the spectral purity and indistinguishability of photons from telecom-wavelength sources by combining Gaussian quasi-phase-matching with Gaussian pump spectral shaping. Without spectral filtering, we used time-of-flight spectrometry to estimate an upper bound spectral purity of 99.9272(6)%, and achieved visibilities of up to 98.5(8)% in two-photon interference experiments with independent sources.

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