Why in news?

Recently, the chairman of the Mission Governing Board of the National Quantum Mission, announced that India plans to launch a quantum satellite within the next 2-3 years to enable quantum communications.

This initiative is part of the country's efforts to advance in quantum technology.

What’s in today’s article?

• National Quantum Mission
• Quantum satellite
• How Are Messages Secured?
• How Can Quantum Physics Protect Messages?
• Implementation of Quantum Key Distribution (QKD)
• Drawbacks of QKD

National Quantum Mission (NQM)

• About
  • NQM, launched by the Department of Science & Technology, aims to harness quantum physics for next-generation communication and sensing systems.
  • While classical physics has driven technological advances like telecommunications, AI, and weather forecasting, it is approaching its performance limits.
  • Quantum physics, offering capabilities beyond classical systems, promises revolutionary devices with enhanced abilities.
• Budget
  • Approved by the Union Cabinet in April 2023 with a budget of Rs 6,000 crore, the NQM will run from 2023 to 2031.
  • A key initiative under the mission is the development of a quantum satellite, scheduled for launch within 2-3 years, to pioneer quantum communications.

Quantum satellite

• It is a communications satellite leveraging quantum physics to secure signals against interception.
• Communication technologies rely heavily on security to prevent unauthorized access during message transmission across networks.
• The rise of quantum computers poses a threat to current encryption methods.
• However, quantum physics also enables advanced security measures, with quantum satellites playing a pivotal role in ensuring robust, next-generation protection.

How Are Messages Secured?

• Encryption as a Solution
  • Modern communication tools like WhatsApp secure messages through encryption.
  • Encryption converts messages into a secret code before transmission, which can only be decoded by the recipient using the correct key.
  • If intercepted, the message remains unreadable without the key.
• Cryptographic Security
  • This system relies on hiding the decryption key behind complex mathematical problems.
  • While the sender's and recipient's devices already have the solution, an eavesdropper would require immense computing power and time to crack the code.

How Can Quantum Physics Protect Messages?

• Quantum Cryptography and QKD
  • Quantum cryptography secures messages using principles of quantum physics, with Quantum Key Distribution (QKD) being its most well-known application.
  • QKD ensures that if an eavesdropper intercepts the key during transmission, the breach is detected, and the sharing is aborted.
• Quantum Measurement for Security
  • Quantum physics states that measuring a quantum system, like a photon, changes its state.
  • If eavesdropper measures photons carrying the key (encoded in two states, 0 and 1), the state will change, alerting the compromise.
• Quantum Entanglement
  • Quantum entanglement links two photons such that a change in one immediately affects the other.
  • This property helps detect eavesdropping, ensuring unconditional security.

Implementation of Quantum Key Distribution (QKD)

• Development and Current Progress
  • While QKD protocols and technologies are still a decade from standardization, progress has been significant:
    • China operates the world’s largest QKD network with three satellites and four ground stations.
    • Experiments since 1992 have extended the distance of reliable QKD transmissions to several hundred kilometres via fibre-optic cables or free space.
• Notable Experiments
• China (2013): Researchers implemented QKD between a ground station and a moving hot-air balloon 20 km above, supporting the feasibility of quantum satellites.
• India (2024): A study by the Raman Research Institute, Bengaluru, found the Indian Astronomical Observatory in Hanle, Ladakh, to be ideal for satellite-based QKD due to low signal loss (44 dB compared to 50 dB in China’s experiment).
• India’s Planned Quantum Satellite
  • The planned satellite will transmit signals at a main wavelength of 810 nm, with uplink and downlink wavelengths at 532 nm and 1550 nm, respectively.
  • The projected beam distance is 500 km.

Drawbacks of QKD

• Criticism by the U.S. National Security Agency (NSA)
  • The NSA recommends post-quantum cryptography over QKD due to the following limitations:
    • Lack of Authentication: QKD doesn’t authenticate the source of the transmission.
    • Hardware Dependence: QKD networks rely on hardware that can’t be easily upgraded or patched.
    • High Costs and Risks: Infrastructure costs and insider threats limit its feasibility for many use cases.
    • Limited Real-World Security: The security achieved depends on hardware and engineering designs, not the theoretical unconditional security promised by quantum physics.
    • Vulnerability to Attacks: Eavesdroppers can cause denial-of-service (DoS) attacks by halting transmissions.
• Restrictions Imposed by Quantum Physics
• No-Cloning Theorem: Quantum information can’t be amplified like classical information, restricting its transmission across large distances.
• Post-Quantum Cryptography as an Alternative
  • Post-quantum cryptography uses advanced classical encryption techniques to resist attacks from both quantum and classical devices, making it a more practical solution in some cases.