India’s first 500 km Quantum Key Distribution (QKD) network
Kartavya Desk Staff
Source: DST
Context: A startup supported under the National Quantum Mission (NQM) — QNu Labs Pvt. Ltd. — has successfully demonstrated India’s first 500 km Quantum Key Distribution (QKD) network.
About India’s first 500 km Quantum Key Distribution (QKD) network:
What it is QKD?
• Quantum Key Distribution (QKD) is a secure communication technology that uses the laws of quantum physics to generate and exchange encryption keys between two parties. Unlike traditional encryption, it ensures that any attempt to intercept or observe the key instantly alters the system, making eavesdropping detectable.
Developed by: The Bengaluru-based quantum startup QNu Labs Pvt. Ltd., supported by the Department of Science and Technology (DST) under the National Quantum Mission (NQM).
How it works?
• QKD transmits streams of light particles (photons) carrying random quantum states through optical fiber.
• Each photon encodes information as qubits (quantum bits).
• If an eavesdropper tries to measure or clone the photons, quantum properties change—alerting the communicating parties.
• After error correction and privacy amplification, both parties obtain a shared secret key used for encrypting data securely.
Types of QKD:
• Prepare-and-Measure Protocols: Use random photon polarization to generate keys and detect eavesdropping. Example: BB84 protocol (most widely used).
• Use random photon polarization to generate keys and detect eavesdropping.
• Example: BB84 protocol (most widely used).
• Entanglement-Based Protocols: Use entangled photon pairs — measuring one instantly determines the state of the other. Intrusions become instantly noticeable.
• Use entangled photon pairs — measuring one instantly determines the state of the other.
• Intrusions become instantly noticeable.
• DV-QKD (Discrete Variable QKD): Uses photon detectors to read discrete quantum states.
• Uses photon detectors to read discrete quantum states.
• CV-QKD (Continuous Variable QKD): Encodes quantum data in amplitude and phase of laser light.
• Encodes quantum data in amplitude and phase of laser light.
Features of the Demonstrated QKD Network:
• 500 km quantum-secure link deployed over existing optical fiber infrastructure.
• Enabled end-to-end encryption using multiple trusted nodes for enhanced reliability.
• Supported by Quantum Suraksha Kavach hardware for high-grade data protection.
• Demonstrated integration of Quantum Random Number Generator (QSIP) technology for superior cryptographic strength.
• Showcases civil–military synergy (STRIDE model) — linking research, industry, and defence sectors.
• Positions India among leading nations in quantum-safe communication and cybersecurity readiness.