The article "Integrated Photonics for Quantum Communications and Metrology" by Laurent Labonté et al. provides a comprehensive review of the advancements and challenges in integrated quantum photonics, focusing on its applications in quantum communication and metrology. The authors highlight the transformative impact of integrated photonics on quantum technologies, emphasizing the second quantum revolution's opportunities. They discuss the key platforms for integrated photonics, including silicon (Si), silicon carbide (SiC), lithium niobate (LN), III-V and III-N semiconductors, and silica, detailing their strengths and weaknesses. In the context of quantum communication, the article explores prepare-and-measure Quantum Key Distribution (QKD) schemes, emphasizing the development of compact and efficient systems. It also delves into multimode quantum photonics, discussing the generation and manipulation of multipartite states, and the potential of high-dimensional entanglement for enhanced security and information distribution. For quantum metrology, the article highlights the use of integrated photonics in optical quantum sensors, particularly in quantum optical coherence tomography (QOCT) and enhanced two-photon absorption (TPA). It also discusses the exploitation of two-photon entangled states for precise qualification of optical materials and biochemical species, showcasing the advantages of quantum approaches in terms of precision, flexibility, and reduced systematic errors. Overall, the article provides a forward-looking perspective on the state-of-the-art developments and open challenges in integrated quantum photonics, emphasizing the importance of hybrid and heterogeneous integration to address the limitations of monolithic platforms and achieve practical, scalable solutions for quantum technologies.The article "Integrated Photonics for Quantum Communications and Metrology" by Laurent Labonté et al. provides a comprehensive review of the advancements and challenges in integrated quantum photonics, focusing on its applications in quantum communication and metrology. The authors highlight the transformative impact of integrated photonics on quantum technologies, emphasizing the second quantum revolution's opportunities. They discuss the key platforms for integrated photonics, including silicon (Si), silicon carbide (SiC), lithium niobate (LN), III-V and III-N semiconductors, and silica, detailing their strengths and weaknesses. In the context of quantum communication, the article explores prepare-and-measure Quantum Key Distribution (QKD) schemes, emphasizing the development of compact and efficient systems. It also delves into multimode quantum photonics, discussing the generation and manipulation of multipartite states, and the potential of high-dimensional entanglement for enhanced security and information distribution. For quantum metrology, the article highlights the use of integrated photonics in optical quantum sensors, particularly in quantum optical coherence tomography (QOCT) and enhanced two-photon absorption (TPA). It also discusses the exploitation of two-photon entangled states for precise qualification of optical materials and biochemical species, showcasing the advantages of quantum approaches in terms of precision, flexibility, and reduced systematic errors. Overall, the article provides a forward-looking perspective on the state-of-the-art developments and open challenges in integrated quantum photonics, emphasizing the importance of hybrid and heterogeneous integration to address the limitations of monolithic platforms and achieve practical, scalable solutions for quantum technologies.