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Q: Fachverband Quantenoptik und Photonik

Q 40: Quantum Optics and Nuclear Quantum Optics II

Q 40.3: Vortrag

Mittwoch, 12. März 2025, 15:00–15:15, AP-HS

Evaluating the quality of heralded photon-number states with high-order moments — •Daniel Borrero Landazabal and Kaisa Laiho — German Aerospace Center (DLR), Institute of Quantum Technologies, Wilhelm-Runge-Str. 10, 89081 Ulm, Germany

Typically, the fidelity and second-order correlation function g(2) are used to characterize number states. While the fidelity gives insights on the purity, a low g(2)-value indicates a low multiphoton contributions of the target state. However, the fidelity is not straightforward to measure in an experimental setup, and g(2) ignores the vacuum component, which degrades the state quality. In this work, we propose and numerically demonstrate that the photon-number parity represents a practical and improved tool in state characterization, when accessed via the higher-order factorial moments of photon number [1]. By taking into account imperfections of photon counting systems [2], we successfully simulate the characteristics of heralded number states up to three photons from a twin beams generated in a non-linear optical process of parametric down-conversion. Furthermore, we express our results in an easy experimentally accessible parameter space, which allows identifying optimal regions for the number-state generation with high-quality.

[1] K. Laiho et al., "Measuring higher-order photon correlations of faint quantum light: a short review", Phys. Lett. A 435, 128059 (2022).

[2] J. Sperling et al., "True photocounting statistics of multiple on-off detectors", Phys. Rev. A 85, 023820 (2012).

Keywords: photon counting; number states; photon-number parity; higher-order moments