Recent advances in room temperature single-photon emitters

Considering the ever-increasing growth of quantum technology and the expansion of its applications into non-laboratory environments, usability at room temperature is becoming more and more critical in these systems. Generating the quantum particle is the first block of a quantum system, and the need to produce stable, indistinguishable, and isolated quantum particles requires extensive studies in these areas. Photons have a quantum nature, exhibit a high coherence time, and are extremely isolated from the surrounding environment; hence, they can be used in higher temperature and approximately room temperature environments, contrary to single atoms, ions, and superconductors. Photons emitted from classical and thermal [light] sources such as lamps and coherent sources like lasers are emitted as clusters and in a random manner, respectively. On the other hand, single-photon emitters have a non-classical nature and are able to provide the necessary quantum particles required for telecommunication and quantum processing. The emitter should perform at room temperature and maintain its stability and emission rate similar to how it performs in lower temperatures to increase its efficiency and facilitate non-experimental applications. Furthermore, the emitter should be minorly influenced by thermal phonons, and the emission wavelength must be stable. Fashioning such single-photon emitters requires special methods and comes with a set of challenges, which are discussed in this article. Firstly, their history, principles, characterizing parameters, and the measuring approaches related to these sources are discussed; afterward, different materials and structures with optimal emission capabilities are investigated and compared.