Jianwei Lee
Email Address
jwlee@nus.edu.sg
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SPECIALTY RESEARCH INST/CTRS
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Publication Asymmetric delay attack on an entanglement-based bidirectional clock synchronization protocol(AMER INST PHYSICS, 2019) Lee, Jianwei; Shen, Lijiong; Cere, Alessandro; Troupe, James; Lamas-Linares, Antia; Kurtsiefer, Christian; Dr Shen Lijiong; CENTRE FOR QUANTUM TECHNOLOGIES© 2019 Author(s). We demonstrate an attack on a clock synchronization protocol that attempts to detect tampering of the synchronization channel using polarization-entangled photon pairs. The protocol relies on a symmetrical channel, where propagation delays do not depend on the propagation direction, for correctly deducing the offset between clocks - a condition that could be manipulated using optical circulators, which rely on static magnetic fields to break the reciprocity of propagating electromagnetic fields. Despite the polarization transformation induced within a set of circulators, our attack creates an error in time synchronization while evading detection.Publication Wide-range wavelength-tunable photon-pair source for characterizing single-photon detectors(OSA - The Optical Society, 2021-01-21) Shen, Lijiong; Lee, Jianwei; Hartanto, Antony Winata; Tan, Pengkian; Kurtsiefer, Christian; CENTRE FOR QUANTUM TECHNOLOGIES; PHYSICS; BIOLOGICAL SCIENCESThe temporal response of single-photon detectors is usually obtained by measuring their impulse response to short-pulsed laser sources. In this work, we present an alternative approach using time-correlated photon pairs generated in spontaneous parametric down-conversion (SPDC). By measuring the cross-correlation between the detection times recorded with an unknown and a reference photodetector, the temporal response function of the unknown detector can be extracted. Changing the critical phase-matching conditions of the SPDC process provides a wavelength-tunable source of photon pairs. We demonstrate a continuous wavelength-tunability from 526 nm to 661 nm for one photon of the pair, and 1050 nm to 1760 nm for the other photon. The source allows, in principle, to access an even wider wavelength range by simply changing the pump laser of the SPDC-based source. As an initial demonstration, we characterize single-photon avalance detectors sensitive to the two distinct wavelength bands, one based on Silicon, the other based on Indium Gallium Arsenide. © 2021 Optical Society of America.