Review on telecom quantum dots: Challenges and perspectives

Single and entangled photons are an essential resource for quantum communication, enabling the transmission of quantum information. For this technology to work on long-distance networks, quantum light sources are needed that produce photonic quantum states, such as single photons, ideally on demand and with a wavelength in the telecommunication wavelength bands. Solid-state semiconductor quantum dots emitting in these wavelength ranges are promising candidates for reliable single-photon sources. This review will give an overview of the current developments, challenges, and milestones reached in this field. We will provide an overview of different growth methods and discuss current state-of-the-art metrics such as single-photon emission, single-photon purity, and indistinguishability. Vital for the device development is a high source brightness, to ensure the transmission speed, necessary for real-world communication. Promising solutions to this are different kinds of micro-cavities, which deploy the Purcell effect for increased brightness and collection efficiency. In this review, first an overview of the growth methods for C-band quantum dots is given (II), followed by applications (III), and an overview of the solutions to current challenges in this field (IV).