2026-04-17T05:15:59Zhttps://recercat.cat/oai/request

oai:recercat.cat:2117/4304962025-07-22T15:43:26Zcom_2072_1033col_2072_452951

QKD: Single Photon Generator and Detector Iriondo Pesarrodona, Ferran Àrees temàtiques de la UPC::Enginyeria de la telecomunicació::Telecomunicació òptica::Fotònica Quantum optics Photonics Òptica quàntica Fotònica Quantum Key Distribution is a communication method following a cryptographic protocol based on key exchange. The keys for encrypting and decrypting are based on physical principles. In (Bennett & Brassard, 2014) is stated, that polarized photons can be used to transmit digital information. The quantum states of photons, so the polarization with 0, 45 or 90 degrees, contains the information. So a quantum channel transmits encrypted information with single photons, which has to be sent and detected. The main part of our project is to provide functional hardware with a single photon source and detector. The purpose will be fulfilled as a basis for a future minor project of Fontys Engineering. The project starts with research on QKD and quantum physics due to the lack of knowledge of the group members about the assigned project topic. In this context, meetings are held with technical support professors Chris Lee and Mark Greuell, who help to learn more about the topic. The next step is a simple experiment involving some filters, a laser and a detector. The aim of it is to understand what the main part of the project is about, getting familiar with the laboratory components, and be able to calculate the attenuation which is needed for the laser in the final experiment of single photons. After creating a document in which the required attenuation is calculated and verified with Mart, the process begins with the development of the layout with all the optical elements and circuits necessary for operation. From this point the ordering of the necessary components starts and then the assembly using breadboards and other simple components provided by the Fontys Applied Sciences department. With the project, a few challenges have to be faced. The first components of the detector circuit were too slow, so faster electronics should eliminate the lack of speed. Also placing the parts on a breadboard is not working because they are too lose, so they are placed on a perfboard. For the optical setup and the Laser circuit, it is important to really calculate everything to not order the wrong parts. Soldering is also challenging in the beginning because some of the students have never done it before. Designing the PCB in KiCad is harder than expected because the software is really complex; however this challenged is faced with the help of the teacher. Outgoing 2025-02-27 Bachelor thesis Open Access Universitat Politècnica de Catalunya