Mr. Kishore Kumar Jinka
Securing Quantum Communication with the No-Cloning Theorem in Quantum Key Distribution
Abstract of Talk: Quantum Key Distribution (QKD) is a secure method of transmitting cryptographic keys using quantum mechanics, providing security based on the fundamental principles of quantum states, such as superposition and entanglement. Unlike classical key distribution methods, which rely on computational difficulty or assumptions of hard-to-solve mathematical problems, QKD ensures security due to the inherent properties of quantum mechanics. One of the most important principles in quantum mechanics that ensures the security of QKD is the No-Cloning Theorem, which states that it is impossible to create an identical copy of an unknown quantum state. This principle contrasts with classical systems, where copying information such as a bit is trivial and does not alter the original data. In quantum systems, copying a quantum state is not possible without disturbing the original state in some way. This disturbance becomes a key feature in QKD, ensuring that any attempt to intercept or measure the qubits exchanged during the key distribution process can be detected. When an eavesdropper intercepts the qubits, they must measure them in order to gain information. However, due to the nature of quantum measurement, any measurement made by the eavesdropper collapses the quantum state, altering it in the process. This disturbance is what makes QKD secure, as it guarantees that if an eavesdropper tries to copy or measure the quantum states, they will inevitably introduce errors. These errors can be detected by the legitimate parties involved in the communication. In protocols like BB84, qubits are encoded in one of four possible states. If the eavesdropper intercepts the qubits, they may not know in which basis the qubits are encoded, and if they measure the qubits in the wrong basis, the qubit’s state will be disturbed. When the legitimate receiver gets the qubit, they may find discrepancies between the state they measure and the original state sent. To detect such discrepancies, the legitimate parties compare a subset of their results over a classical channel. If the error rate is high, it indicates that an eavesdropper has interfered with the communication, and they discard the key. The ability to detect eavesdropping is possible because of the No-Cloning Theorem. Without this principle, if the eavesdropper could clone the quantum states without disturbing them, they could extract the information without introducing detectable errors. In summary, Quantum Key Distribution relies on the principles of quantum mechanics, including superposition, entanglement, and the No-Cloning Theorem, to ensure the secure exchange of cryptographic keys. The No-Cloning Theorem guarantees that any attempt to intercept or copy the qubits during transmission will disturb the quantum states, creating errors that can be detected by the legitimate parties involved. This provides a level of security that classical cryptographic methods cannot offer, making QKD resistant to eavesdropping and ensuring the integrity of the key exchange.