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Q: Fachverband Quantenoptik und Photonik

Q 47: Quantum Technologies – Sensing II

Q 47.7: Vortrag

Donnerstag, 5. März 2026, 12:30–12:45, P 5

Calibrated Generation of Heralded Single Photons — •Daniel Borrero Landazabal and Kaisa Laiho — German Aerospace Center (DLR), Institute of Quantum Technologies, Wilhelm-Runge-Str. 10, 89081 Ulm, Germany

Heralded single-photon sources based on parametric down-conversion (PDC) are indispensable in many quantum sensing applications. To characterize such emitters conventionally the second-order correlation function g_h⁽²⁾ of the heralded state has been used. However, the practical deployment of such sources demands a more rigorous, loss-tolerant characterization. We employ a waveguided type-II PDC process pumped by a pulsed laser, generating orthogonally polarized photon pairs with a low optical mode number. After separating the photon pairs–signal and idler– from each other, the detection in idler with a superconducting nanowire single-photon detector heralds the target state in signal. By recording counts of coincidences and singles, we measure g_h⁽²⁾ and extract loss-tolerantly the mean photon number and photon-number parity with a high accuracy. The former delivers access to the residual multiphoton contamination, while the latter provides a direct measure of the non-classicality of the heralded states. We demonstrate that these figures of merit provide a stringent benchmark for a high-quality single-photon generation, surpassing the information delivered by g_h⁽²⁾ alone. Our results pave the way for the generation of calibrated single-photon probes and may find usage for example in quantum radiometry to achieve precision in quantum optics experiments.

Keywords: quantum radiometry; single-photon state; photon number parity; quantum metrology