Nanotechnology Perceptions ISSN 1660-6795 www.nano-ntp.com Nanotechnology Perceptions 20 No. S15 (2024) 2749-2761 Quantum Computing and Its Implications for Cryptography: Assessing the Security and Efficiency of Quantum Algorithms Dr. K. L. Sumathy 1 , M. Megala 2 , Dr. Sasanko Sekhar Gantayat 3 , Dr. B.V. RamaKrishna 4 1 Assistant professor, Department of Computer science, st Anne's Arts and science college, India 2 Assistant professor, Department of Artificial intelligence and data science, Panimalar Engineering college, India 3 Associate Professor, Department of Computer Science and Engineering, School of Computer Science & Artificial Intelligence SR University, India. 4 Associate Professor, Department of CSE, Aditya College of Engineering and Technology, India Email: drsumil7411@gmail.com Quantum computing can be regarded as a disruptive enabling technology that can pose a threat to traditional cryptography as it invented new approaches to encrypt data. This paper will compare the level of security that accompanies quantum algorithms as well as the level of efficiency. Specifically, we examine the impact of efficient quantum computing on traditional cryptography and propose techniques against quantum invasions. Four quantum algorithms are analyzed for their efficiency and security benefits in the post-quantum era: Grover’s Algorithm, Shor’s Algorithm, The Quantum Key Distribution (QKD), Lattice-based cryptography. The results reveal that Grover’s algorithm improves search time complexity from O(n) to O(√n), which is advantageous over large data sets. As it will be clear shortly, Shor’s algorithm challenges RSA encryption because it outperforms classical algorithms in factoring large integers. QKD presents secure key exchange protocols that cannot be breached notwithstanding the attempts made using quantum computing. Lattice-based schemes are quantum-resistant alternatives based on the security of certain hard mathematical problems. Based on our experimental results, computational efficiency can be improved, but new cryptographic systems will have to be developed for the mitigation of quantum- related vulnerabilities. This research shows the importance of quantum-resistant cryptographic techniques to ensure data security in the emerging quantum computing era. Keywords: Quantum Computing, Cryptography, Grover’s Algorithm, Lattice-based Cryptography, Quantum Key Distribution (QKD).