Quantum Satellite

Why in News?

Recently, the chairperson of the National Quantum Computing Mission said India plans to launch a quantum satellite in “2-3 years for quantum communications”.

What is Quantum satellite?

To know about National Quantum Mission, click here.

• Quantum communication – It  relies on individual photons and quantum principles to carry quantum information.

• Quantum satellite - These are communication satellites that uses quantum physics to secure its signals.
• Quantum cryptography  - It uses quantum key distribution(QKD) to secure messages.
• Quantum Key Distribution (QKD) – QKD involves sending encrypted data as classical bits over networks, while the keys to decrypt the information are encoded and transmitted in a quantum state using qubits.
• QKD enables two parties to produce a shared random secret key (encryption key) known only to them.
• Quantum measurement — It is the act of measuring the properties of a quantum system, like a photon (the subatomic particle of light).
• According to the rules of quantum physics, a quantum measurement changes the state of the system.
• Methods of quantum encryption
  • Encoding the key  in a stream of photons (in two states, one representing 0 and the other 1) and any act of measuring them changes the state of the photons.
  • Quantum entanglement - when two photons are entangled, any change to one particle will instantaneously change the other.
• Applications of quantum communication
  • Satellite based Quantum Key Distribution (QKD) over larger distances
  • Protecting sensitive client information in Banking/ Finance Industry
  • Protecting customer credit card information
  • Government and defence industry
  • Protecting high value/sensitive data in remote data centres
  • NavIC based RS-Key distribution

What are worldwide developments related to quantum communication?

• China & Japan have successfully demonstrated Quantum Communication experiments from satellite to ground.
• China  - It currently operates the world’s largest QKD network with three quantum satellites and four ground stations.
• Europe - European Space Agency (ESA) is developing a technology demonstration satellite known as Eagle-1.
• Germany - Qube satellite was launched in August 2023 to test QKD capabilities.

• India’s progress:
  • Single photon based inter-building free space quantum communication link was established over a distance of ~300m of atmospheric channel.
  • 2-way quantum secured client-to-client live video conferencing demonstration has been demonstrated.
  • NavIC  enabled synchronization mechanism has been implemented.
  • BB84 protocol-based quantum key distribution(QKD) protocol was created.

What are the limitations of QKD?

• Lack of source verification - QKD does not provide a means to authenticate the QKD transmission source.
• Upgradation difficulty - Since QKD is hardware-based, QKD networks can’t be upgraded or patched easily.
• High cost - QKD increases infrastructure costs that eliminate many use cases from consideration.
• Limited security - The actual security provided by a QKD system is not the theoretical unconditional security from the laws of physic but rather the more limited security that can be achieved by hardware and engineering designs.
• Denial-of-service attack - Since eavesdroppers can cause a transmission to stop, they can deny the use of a transmission by its intended users (a.k.a. a).
• Restrictions on quantum physics - non-quantum information can be amplified before being transmitted across large distances whereas the no-cloning theorem prohibits the amplification of quantum information.
• Capacity limitation - Even the best optical fibers/ terrestrial free space can carry these photons only up to few hundreds of kilometres before light absorption makes the process impossible.

Post-quantum cryptography refers to cryptographic techniques that resist attacks from both quantum and classical devices using more advanced classical encryption.

Reference

The Hindu | Quantum Satellite