India Demonstrates 500 km Quantum Key Distribution Network

• 08 Nov 2025

Source: PIB 

Why in News? 

In a landmark achievement under the National Quantum Mission (NQM), Startup QNu Labs demonstrated India’s first 500 km Quantum Key Distribution (QKD) network over existing optical fiber infrastructure. 

• This strengthens India’s quantum capabilities and advances quantum-secure communication and cyber defense. 

What is Quantum Key Distribution (QKD) Network? 

• About: QKD is a secure communication technology that uses the principles of quantum mechanics to generate and share encryption keys between two parties, ensuring that the data exchanged cannot be intercepted or hacked — even by quantum computers.  
  • Its core promise is to detect the presence of any third party trying to eavesdrop on the key exchange. 
• Core Principle: The strong security of QKD is based on two key quantum principles: 
  • No-Cloning Theorem: An unknown quantum state cannot be copied, so an eavesdropper cannot duplicate photons without changing them. 
  • Observer Effect: Measuring quantum particles disturbs them, meaning any attempt to spy on the key creates detectable changes. 
• Functioning: QKD uses qubits (quantum bits) transmitted through optical fibers via total internal reflection to securely exchange encryption keys between two users. 
  • Unlike classical bits, qubits, encoded on photons, are highly sensitive to interference, and any eavesdropping disrupts them, enabling tamper-evident quantum encryption. 
  • QKD enables distant users to create a shared secret key authenticated by classical cryptography. 

• Significance: 
  • Future-Proof Security: QKD is inherently secure against quantum computers, relying on quantum laws rather than computational difficulty, unlike classical encryption. 
  • Eavesdropper Detection: It offers provable, information-theoretic security, detecting any intrusion and allowing compromised keys to be discarded. 
  • Critical Infrastructure Protection: QKD safeguards government, military, financial, and national assets, preventing the “harvest now, decrypt later” threat. 
  • Digital Sovereignty and Innovation: Indigenous QKD development enhances digital sovereignty, builds trust in digital ecosystems, and drives technological advancement and economic opportunities. 

Frequently Asked Questions (FAQs) 

1. What is Quantum Key Distribution (QKD)? 
QKD is a quantum-secure communication technology that generates encryption keys using quantum mechanics, ensuring tamper-evident and unhackable data exchange. 

2. What is the National Quantum Mission (NQM)? 
NQM is India’s flagship initiative to promote quantum research, communication, computing, and sensing, aiming to make India a global leader in quantum technologies. 

3. How does QKD enhance cybersecurity for India? 
By providing future-proof, tamper-evident encryption, QKD protects government, military, and financial networks against quantum and classical cyber threats. 

UPSC Civil Services Examination Previous Year Question (PYQ)   

Q. Which one of the following is the context in which the term "qubit" is mentioned? (2022)

(a) Cloud Services   

(b) Quantum Computing   

(c) Visible Light Communication Technologies   

(d) Wireless Communication Technologies   

Ans: (b)