Syllabus

GS 3: Achievements of Indians in science & technology; indigenization of technology and developing new technology

Context: 

Recently, DRDO and IIT Delhi have successfully demonstrated secure quantum communication.

More on the News

• They demonstrated secure quantum communication using quantum entanglement over a free-space distance of more than 1 kilometer.
• The experiment achieved a secure key rate of around 240 bits per second with a quantum bit error rate below 7%.
• It has been developed under the project titled ‘Design and Development of Photonic Technologies for Free Space QKD’, sanctioned by the Directorate of Futuristic Technology Management (DFTM), DRDO.
• India has stepped into a new quantum era of secure communication which the Raksha Mantri described as a future game-changer in modern warfare and national security.

What is quantum entanglement

• When two or more photons are created in a special way, they become connected which means if you measure one photon, you immediately know the result for the other, even if they are far apart. 
• This strange connection is called “quantum entanglement”. It cannot be explained by normal or classical physics; it only makes sense in quantum science.
• Quantum cryptography refrers to an encryption to secure and transmit data in a way that cannot be hacked.

What is Quantum communication

• Quantum communication refers to using ideas from quantum physics, especially entanglement, to create ultra-secure communication channels.
• In one method, like the one demonstrated by the IIT-Delhi team, entangled photons are used to send information between two points. 
• If a third person tries to intercept the data, the connection is immediately disturbed. This alerts the users that the channel is no longer secure.
• This makes quantum communication very useful in defence, as it protects against hackers or powerful computers trying to break into the system.
• One key technique used in quantum communication is called Quantum Key Distribution (QKD), which helps share secret keys safely between two parties.

How does Quantum Key Distribution (QKD) functions

Imagine X wants to send a private message to Y. X can mail it to Y’s house—everyone knows Y’s address, but only Y has the key to open the mailbox. 

• Email works in a similar way: Y’s email ID is public but only she knows the password to read the message.

Quantum Key Distribution (QKD) works a bit differently. Its main goal is not to send the message but to help X and Y share the same secret key securely. 

Once they have this key, they can use normal methods like AES (Advanced Encryption Standard) to encrypt and decrypt their messages.

So, QKD doesn’t hide the message itself but makes sure that only X and Y get the key to lock and unlock it and in a way that no one else can steal it without being noticed.

There are two types of QKD:

1. Prepare-and-measure QKD: X prepares photons in certain states and sends them to Y, who measures them.

2. Entanglement-based QKD: A special device creates two entangled photons, sending one to X and one to Y. Because they are linked, any tampering can be detected.

• This makes QKD one of the safest methods for sharing encryption keys—perfect for secure communication in defence and other critical areas.

Significance 

• Quantum Cybersecurity: Makes unbreakable communication channels, which cannot be hacked in to or have their data stolen, using quantum mechanical rules.
• Long-Distance Quantum Key Distribution (QKD): Demonstrate the feasibility of secure encryption-key transference over long-distances.
• Quantum Internet Capability: Provides a building block of connected quantum networks, which are necessary for the quantum internet ecosystem in the future.
• Real-Time Uses: Showing for use in real-time in defence, banking and critical infrastructure communication

Mains Questions

Discuss the concept of Quantum Key Distribution (QKD) and evaluate its significance in strengthening India’s cybersecurity and strategic communication capabilities in the era of quantum technologies. (10M,150W)