Work

Hyperspectral imaging of downconverted photons in angle phase-matched nonlinear crystals

Year: 2026

Type: article

Abstract: Spontaneous Parametric Down-Conversion (SPDC) is key to generating broadband spectrally entangled photons for quantum optical spectroscopy. Here we use a common-path birefringent interferometer to experimentally map the spatial-spectral distribution of SPDC in Type I and II β-barium borate crystals using hyperspectral k-space imaging. Under broadband pulsed pumping, we observe strong spatial variations in the spectra, with distinct features for each phase-matching type. Simulations based on biphoton amplitudes and phase-matching conditions qualitatively match our results. This spatial-spectral mapping enables control over biphoton entanglement entropy, paving the way for optimized quantum light sources for material spectroscopy.

Source: Optics Letters

DOI: 10.1364/ol.587889

Authors: Evan J. Kumar, Lorenzo Uboldi, Cristian Manzoni, Giulio Cerullo, Ajay Ram Srimath Kandada

Institution: Politecnico di Milano

Language: English

Topic: Quantum Information and Cryptography

Subfield: Artificial Intelligence

Field: Computer Science

Domain: Physical Sciences

Open Access status: gold

Funder: National Science Foundation

Award: CAREER: Nonlinear Dynamics of Exciton-Polarons in Two-Dimensional Metal Halides Probed by Quantum-Optical Methods