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Raphaël Guitter

Publications and source records attributed to Raphaël Guitter.

2 recordsLinked to original sources

Entanglement-enabled image transmission through complex media

Scattering in complex media scrambles light, thus obscuring images and limiting applications from astronomy to microscopy. Existing computational and wavefront-shaping methods treat scattering as a linear optical-wave inversion problem that aims to render the medium transparent by inverting the scattering process. As classical approaches, they do not account for the quantum nature of the incident field. Here, we demonstrate a quantum-entanglement-based method that enables selective image transmission through complex media. The medium is effectively turned into a quantum-classical image filter via wavefront shaping - images encoded on an entangled two-photon state are transmitted faithfully, while those carried by classical light remain fully scattered and unreadable. This method exploits a property of quantum entanglement - the preservation of photon correlations across multiple measurement bases - that has no classical counterpart. Therefore, we establish an approach for controlling light in complex media by tailoring solutions to the quantum properties of the input state, with potential applications in secure information transmission by rendering channels opaque to classical signals while preserving the quantum link.

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Accidental coincidences in camera-based high-dimensional entanglement certification

High-dimensional entangled states, such as spatially-entangled photon pairs produced by Spontaneous Parametric Down-Conversion (SPDC), are a key resource for quantum technologies. In recent years, camera-based coincidence counting approaches have considerably improved the ability to characterize them in terms of speed and dimensionality. However, these methods have limitations, including in most of them the necessity to subtract accidental coincidences. Here, we study the role of these accidentals in entanglement certification for a single-photon avalanche diode (SPAD) array and an intensified time-stamping (Tpx3Cam) camera. Using both Einstein-Podolsky-Rosen (EPR) and entropy-based criteria, we show that the level of accidental coincidences - determined by the temporal characteristics of the camera - and whether they are subtracted critically impact entanglement certification. In particular, we demonstrate that current single-photon camera technologies enable entanglement certification without accidental subtraction only if a Gaussian approximation is applied to the measured two-photon state. Our work is important for developing quantum-optics application in adversarial scenarios, such as high-dimensional quantum key distribution (HD-QKD), and also for loophole-free experimental testing of quantum foundations.

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