Temporal-spectral modes of light provide a fundamental window into the nature of atomic and molecular systems and offer robust means for information encoding. Methods to precisely characterize the temporal-spectral state of light at the single-photon level thus play a central role in understanding quantum emitters and are a key requirement for quantum technologies that harness single-photon states. Here we demonstrate an optical reference-free method, which melds techniques from ultrafast metrology and single-photon spectral detection, to characterize the temporal-spectral state of single photons. This provides a robust, wavelength-tunable approach for rapid characterization of pulsed single-photon states that underpins emerging optical quantum technologies based upon the temporal-spectral mode structure of quantum light.
@article{arxiv.1709.05248,
title = {Measuring the single-photon temporal-spectral wave function},
author = {Alex O. C. Davis and Valérian Thiel and Michał Karpiński and Brian J. Smith},
journal= {arXiv preprint arXiv:1709.05248},
year = {2018}
}