Quantum technologies are generating a lot of buzz recently. Quantum emitters and detectors have a wide range of use in several fields such as quantum communication, computation, sensing and the biomedical field.
Quantum emitters and detectors make use of photons, or quanta of light. Thus, photons are the quantum particles that describe the particle nature of light. In the age of quantum-assisted technologies, photons can act as one bit of information, or a “qubit”. Therefore, one needs to generate photons which can be done by exciting an emitter, or a two-level quantum system.
Basically what happens is, an external pump source is used to excite the emitter system. After a certain amount of time, the emitter returns to a lower energy level by emitting a photon. Next, these photons can be passed through a quantum channel or device for implementing certain quantum protocols. The final step in most protocols is corresponding to a measurement performed on these photons which requires a highly sensitive and efficient detector that can detect light at the single photon level, i.e., single photon detectors.
Various material systems and mechanisms are being explored which can realize a perfect single-photon source and detector. Solid-state emitters are being heavily pursued to develop good single-photon sources for scalable technology. Detectors with high detection efficiencies are also being equally pursued.
Materials called two-dimensional van der Waals (2D-vdW) materials show a lot of promise. These materials are atomically thin and layered. They have a lot of advantages such as being able to form heterostructures that gives one more degrees of control over the physical properties of the system. They have tunable optoelectronic properties and can also integrate with photonic sources. Further, these materials can act as good hosts for single photon emitters as well as have competent photodetection properties for single photon detectors. Thus, it can be used for either purposes, although the engineering aspects for fabricating a single photon source or detector from these materials are quite different!
Ms. Madhura Ghosh Dastidar 
Mr. Immanuel Thekkooden 
Prof. Pramoda K. Nayak 
Prof. Vidya Praveen Bhallamudi
A recent review article published by Ms. Madhura Ghosh Dastidar, Mr. Immanuel Thekkooden, Prof. Pramoda K. Nayak and Prof. Vidya Praveen Bhallamudi from the Department of Physics, Indian Institute of Technology Madras, Chennai, India, discusses the progresses made in the field of 2D vdW material-based quantum technologies. They have surveyed and understood the works done by various research groups over the world. They have compiled the studies reported on emitter and detector systems based on certain material platforms – such as hexagonal boron nitride, transition metal dichalcogenides, canonical graphene and their heterostructures that showcases the versatility of 2D vdW materials. Despite the progress made, more research is required before two-dimensional van der Waals materials can be commercialized especially, in the cases of both emission and detection. The authors also indicate the areas of research that can be further explored for more exciting physics in the field of 2D material-based photon emitters and detectors.
Article by Akshay Anantharaman
Here is the original link to the paper:
https://pubs.rsc.org/en/content/articlelanding/2022/nr/d1nr08193d
