Ms. Kanagalakshmi Murugan

Quantum Memory Implementation for Reducing Photon Loss in Cryptographic Networks

Abstract:

Quantum cryptography leverages the fundamental principles of quantum mechanics to provide theoretically unbreakable encryption, with Quantum Key Distribution (QKD) being the most prominent application. While QKD ensures secure key exchange, its practical deployment over long distances is significantly limited by photon loss in optical fibers or through atmospheric transmission. Photons, the carriers of quantum information, are easily absorbed or scattered, leading to reduced signal strength and increased error rates over extended links. Unlike classical systems, quantum signals cannot be amplified due to the no-cloning theorem, which prevents copying unknown quantum states. This poses a major challenge for long-range quantum communication. To overcome this limitation, researchers have proposed quantum repeaters, which divide long channels into shorter segments and rely on quantum memory to temporarily store quantum states. Quantum memory can hold entangled photons or qubits until entanglement is successfully established in the next segment, enabling a process known as entanglement swapping. This greatly reduces the impact of photon loss by avoiding the need for direct transmission over the full distance. Additionally, it enhances key generation rates and improves the fidelity of entangled states. The integration of quantum memory with QKD protocols paves the way for scalable and robust quantum networks. As memory lifetimes, fidelity, and storage capacities improve, practical quantum communication over hundreds or even thousands of kilometers becomes feasible. Continued research in this direction is critical for building a global quantum internet and securing next-generation communication infrastructure.