Signatures of Non-Classical Light Emission from Semiconductor Lasers

Nowadays, single-photon sources can be generated experimentally through a wide variety of platforms [1]. Semiconductor quantum dots [2] have demonstrated impressive performance in terms of photon purity and indistinguishability, particularly in Hong-Ou-Mandel experiments. Another widely used method involves nonlinear crystals, which can generate entangled photon pairs via nonlinear processes such as spontaneous parametric down-conversion (SPDC) or spontaneous four-wave mixing (SFWM). These are heralded single-photon sources, rather than deterministic ones, yet they remain essential tools in quantum optics [3]. Moreover, among the most commonly used single photon sources, there are NV centres in diamonds [4]. These single-photon sources emit quantum states of light, i.e., those that have no classical counterpart.