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A scheme to distinguish entangled two-photon-polarization states (ETP) from two independent entangled one-photon-polarization states (EOP) is proposed. Using this scheme, the experimental generation of ETP by parametric down-conversion is…
Two-photon states generated from spontaneous parametric down-conversion (SPDC) can display entanglement in all degrees of freedom (DoFs) of light, including spatial, temporal, and polarization. The coupling between different DoFs of a…
It was shown recently that entanglement of identical particles has a feature called dualism [Phys. Rev. Lett. 110, 140404 (2013)], which is fundamentally connected with quantum indistinguishability. Here we report an experiment that…
Chromatic dispersion is one of the main limitations to the security of quantum communication protocols that rely on the transmission of single photons in single mode fibers. This phenomenon forces the trusted parties to define longer…
We demonstrate polarization entanglement in highly non-degenerate photon pairs, generated through Type-0 spontaneous parametric down conversion (SPDC) using bulk periodically poled Lithium Niobate (PPLN) crystals. Through the utilization of…
We demonstrate an optical-fiber based source of polarization entangled photon-pairs with improved quality and efficiency, which has been integrated with off-the-shelf telecom components and is, therefore, well suited for quantum…
Spontaneous parametric down-conversion is a vital method for generating correlated photon pairs in the visible and near-infrared spectral regions; however, its extension to X-ray frequencies has faced substantial barriers. Here, we present…
The thorough characterization of entangled-photon sources is vital for their optimal use in quantum communication. However, this task is not trivial at telecommunication wavelengths. While cameras and spectrometers are well developed for…
In this work we propose and analyse a scheme where the full spatio-temporal correlation of twin photons/beams generated by parametric down-conversion is detected by using its inverse process, i.e. sum frequency generation. Our main result…
Integrated photonics represents a technology that could greatly improve quantum communication networks in terms of cost, size, scaling, and robustness. A key benchmark for this is to demonstrate their performance in complex quantum…
We use polarization-entangled photon pairs to demonstrate quantum nonlocality in an experiment suitable for advanced undergraduates. The photons are produced by spontaneous parametric downconversion using a violet diode laser and two…
We report an experiment in which one determines, with least tomographic effort, whether an unknown two-photon polarization state is entangled or separable. The method measures whole families of optimal entanglement witnesses. We introduce…
A bi-photon polarization-frequency entanglement source was realized by shaping the phase-matching function of a poled KTP crystal. It provides a simple method to achieve either polarization or spectral entanglement in a simple collinear…
Integrated entangled photon-pair sources are key elements for enabling large-scale quantum photonic solutions, and addresses the challenges of both scaling-up and stability. Here we report the first demonstration of an energy-time entangled…
The aim of this review paper is to enlighten some recent progresses in quantum optical metrology in the part of quantum efficiency measurements of photo-detectors performed with bi-photon states. The intrinsic correlated nature of entangled…
Direct spectral characterization of a quantum photon-pair source usually involves cumbersome, costly, and time-consuming detection issues. In this study, we experimentally characterize the spectral properties of a type-II phase-matched…
Quantum imaging is an advanced method for microscopy or investigating the optical properties of materials or bio-medical inspections with high accuracy, low noise, and extremely low photo-damage. In previous work, we proposed a quantum…
The heralded generation of entangled states is a long-standing goal in quantum information processing, because it is indispensable for a number of quantum protocols. Polarization entangled photon pairs are usually generated through…
We present results of a bright polarization-entangled photon source operating at 1552 nm via type-II collinear degenerate spontaneous parametric down-conversion in a periodically poled potassium titanyl phosphate crystal. We report a…
Hyperentanglement offers enhanced capacity for quantum information processing and communication protocols, especially in combination with robust high-dimensional degrees of freedom such as frequency-bin encoding. Here, we present a…