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arXiv · 2510.06196

Optimised spectral purity of unfiltered photons via pump and nonlinearity shaping

Tommaso Faleo·Christopher L. Morrison·Roméo Beignon·Francesco Graffitti·Vikas Remesh·Stefan Frick·Alessandro Fedrizzi·Gregor Weihs·Robert Keil
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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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Tommaso Faleo, Christopher L. Morrison, Roméo Beignon, Francesco Graffitti, Vikas Remesh, Stefan Frick, Alessandro Fedrizzi, Gregor Weihs, Robert Keil. 2025-10-07. Optimised spectral purity of unfiltered photons via pump and nonlinearity shaping. https://doi.org/10.1063/5.0315044

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