Quantum cryptography is a topic of considerable interest. A simple and robust experiment and theory for a senior level undergraduate investigation of quantum key distribution are described. In the proposed experiment, key principles from the BB84 protocol, used in quantum cryptography, are emulated using an optical apparatus and computational scripts independently.

Paper production and recycling result in large amounts of recycled paper sludge (RPS) that is currently being disposed of in very costly and unsustainable practices, raising the importance of developing green solutions for waste management. The use of nanocellulose (NC) as the next generation of materials has gained much attention due to its economic potential. However, there are substantial challenges in NC extraction, detection, and quantification methods. In this study, NC was produced from RPS as a means of converting waste into a resource. The process included a short, 30 min ozonation (21 mg O₃/g RPS), which allowed a sufficient delignification and facilitated the following hydrolysis step. Among all tested durations, a 4-h hydrolysis with 64% w/w sulfuric acid resulted in the highest NC production. Fluorescent staining by calcofluor white was used for simple and low-cost detection of NC in-situ. Crude NC showed a significant 63% dye uptake of 0.1 ppm acid red 131 within 30 min. Compared to the standard disposal methods of RPS, its utilization for NC production supports the circular economy concept and significantly contributes to the development of cellulose bio-based nanomaterials for water treatment applications.

Quantum cryptography continues to be an area of significant research and educational interest. Here, a straightforward and reliable approach to both the experimental and theoretical aspects of quantum key distribution is presented, tailored for senior undergraduate students. Focusing on illustrating the essential concepts of the B92 protocol through a combination of optical experiments and custom-developed computational tools, this work offers a thorough exploration of quantum cryptography according to the principles of the B92 protocol.

Quantum cryptography continues to be an area of significant research and educational interest. Here, a straightforward and reliable approach to both the experimental and theoretical aspects of quantum key distribution is presented, tailored for senior undergraduate students. Focusing on illustrating the essential concepts of the B92 protocol through a combination of optical experiments and custom-developed computational tools, this work offers a thorough exploration of quantum cryptography by B92 protocol’s principles.