Telecom WavelengthsInP‐Based Quantum Dots for Quantum Communication

Quantum dots (QDs), also known as artificial atoms, are among the recently explored hardware platforms for photonic quantum technologies. They offer a range of advantages that make them particularly well-suited for building quantum communication networks over optical fiber channels. One of the most prominent features of QDs is the ability to be easily and deterministically integrated into photonic devices and photonic circuits. They also exhibit near-unity internal quantum efficiency and emit nearly Fourier-transform-limited single photons of high purity and entangled photons. QDs emitting at optical fiber communication wavelengths, especially in the telecom C-band, which corresponds to the spectral range of the lowest attenuation in silica fibers, are very promising for long-distance quantum communication. This makes the development of QD-based quantum light sources for these wavelength ranges of particular interest. This chapter gives an overview of recent developments in InP-based QDs, which are one of the candidates providing emission in this spectral window. These advancements include lowering the spatial density of nanostructures in this material system, increasing their in-plane symmetry, developing high-reflectivity distributed Bragg reflectors, and incorporating them in microcavities and other photonic structures to increase photon extraction efficiency to generate the highest-purity single photons at 1550 nm.