Optimized spectral purity of unfiltered photons via pump and nonlinearity shaping

T Tommaso Faleo (Institut für Experimentalphysik, Universität Innsbruck 1 , Technikerstr. 25, 6020 Innsbruck,) C Christopher L. Morrison (Institute of Photonics and Quantum Sciences, School of Engineering and Physical Sciences, Heriot-Watt University 2 , Edinburgh EH14 4AS,) R Roméo Beignon (Institut für Experimentalphysik, Universität Innsbruck 1 , Technikerstr. 25, 6020 Innsbruck,) F Francesco Graffitti (Institute of Photonics and Quantum Sciences, School of Engineering and Physical Sciences, Heriot-Watt University 2 , Edinburgh EH14 4AS,) V Vikas Remesh (Institut für Experimentalphysik, Universität Innsbruck 1 , Technikerstr. 25, 6020 Innsbruck,) S Stefan Frick (Institut für Experimentalphysik, Universität Innsbruck 1 , Technikerstr. 25, 6020 Innsbruck,) A Alessandro Fedrizzi G Gregor Weihs (Institut für Experimentalphysik, Universität Innsbruck 1 , Technikerstr. 25, 6020 Innsbruck,) R Robert Keil (Institut für Experimentalphysik, Universität Innsbruck 1 , Technikerstr. 25, 6020 Innsbruck,)

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 downconversion sources, demonstrating high two-photon interference visibility using only moderate bandpass spectral filtering. Here, we optimized 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.

Article Details

Volume / Issue Vol. 128, Issue 20
Published May 18, 2026
ISSN 0003-6951
Publisher American Institute of Physics

Journal Info

Applied Physics Letters

American Institute of Physics

ISSN: 0003-6951 Physical Sciences

Authors (9)

T

Tommaso Faleo

Institut für Experimentalphysik, Universität Innsbruck 1 , Technikerstr. 25, 6020 Innsbruck,

C

Christopher L. Morrison

Institute of Photonics and Quantum Sciences, School of Engineering and Physical Sciences, Heriot-Watt University 2 , Edinburgh EH14 4AS,

R

Roméo Beignon

Institut für Experimentalphysik, Universität Innsbruck 1 , Technikerstr. 25, 6020 Innsbruck,

F

Francesco Graffitti

Institute of Photonics and Quantum Sciences, School of Engineering and Physical Sciences, Heriot-Watt University 2 , Edinburgh EH14 4AS,

V

Vikas Remesh

Institut für Experimentalphysik, Universität Innsbruck 1 , Technikerstr. 25, 6020 Innsbruck,

S

Stefan Frick

Institut für Experimentalphysik, Universität Innsbruck 1 , Technikerstr. 25, 6020 Innsbruck,

A

Alessandro Fedrizzi

G

Gregor Weihs

Institut für Experimentalphysik, Universität Innsbruck 1 , Technikerstr. 25, 6020 Innsbruck,

R

Robert Keil

Institut für Experimentalphysik, Universität Innsbruck 1 , Technikerstr. 25, 6020 Innsbruck,