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THU: Thursday Contributed Sessions

THU 13: Poster Session: Applications

THU 13.41: Poster

Thursday, September 11, 2025, 16:30–18:30, ZHG Foyer 1. OG

Mode-selective low-noise up-conversion of light with an all-telecom quantum pulse gate — •Ankita Khanda, Laura Serino, Cristof Eigner, Michael Stefszky, Benjamin Brecht, and Christine Silberhorn — Integrated Quantum Optics, Institute for Photonic Quantum Systems (PhoQS), Paderborn University, Warburger Straße 100, Paderborn 33098, Germany

The quantum pulse gate (QPG) is a highly selective coherent temporal mode filter operating at a single-photon level via sum frequency generation (SFG) and group-velocity phasematching in a periodically poled lithium niobate waveguide. Coherent time-frequency filtering is the most efficient noise elimination method in the spectral-temporal domain, making the QPG an ideal candidate for detection in free-space applications, such as deep space communications, where few-photon detection and noise rejection from background light are essential. There is a strong advantage in moving operation to all-telecom wavelengths, thus allowing utilization of a higher-efficiency type 0 phasematching process, easy integration into fiber-optic networks, and reduced system complexity. However, other linear and non-linear processes impact the type 0 SFG and become sources of noise in the output signal, necessitating further feasibility studies. In this work, we implement the telecom QPG (tQPG) and study the efficiency of the SFG process, as well as investigate the associated noise effects impacting the SNR of the detectable signal. We achieved 83.4% efficiency at 1.08 mW average pump power with 4x10^-3 noise photons/pulse, paving the way for efficient low-noise long-range detection in free space.

Keywords: Coherent time-frequency filtering; Lithium niobate waveguide; Frequency conversion; Integrated quantum optics