Micius Quantum Satellite

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The Micius satellite, formally known as the Quantum Experiments at Space Scale (QUESS) satellite, is the world’s first quantum communications satellite that has established a global quantum communication network.

What are the core capabilities and experimental achievements of Micius?

  1. High-Speed Satellite-to-Ground Quantum Key Distribution (QKD):
    • Function: It is capable of sending an unconditionally secure encryption key (quantum key) from the satellite down to a ground station using photons (qubits). The security is guaranteed by the laws of quantum mechanics.
    • Achievement: Successfully demonstrated QKD over distances of up to 1,200 kilometers, achieving a key generation rate significantly higher than would be possible with a terrestrial fiber link over that distance.
  2. Quantum Entanglement Distribution over Long Distances:
    • Function: The satellite has an onboard source to generate pairs of entangled photons (photons whose quantum states are linked, regardless of distance) and send one photon from the pair to each of two widely separated ground stations.
    • Achievement: Distributed entangled photons to two ground stations separated by over 1,200 kilometers, which is a record distance for preserving quantum entanglement. This feat is crucial for future quantum repeaters and the quantum internet.
  3. Ground-to-Satellite Quantum Teleportation:
    • Function: Successfully performed quantum teleportation, where the quantum state of a photon on the ground is transferred to a distant photon (that is part of an entangled pair) held by the satellite.
    • Achievement: Demonstrated quantum teleportation from a ground station to the satellite over distances ranging from 500 to 1,400 kilometers.
  4. Enabling Intercontinental Quantum Communication:
    • Function: By acting as a “trusted relay,” Micius receives a quantum key from one ground station and then sends the same key to a second, geographically distant ground station, linking them securely.
    • Achievement: Used as a trusted relay to perform intercontinental quantum key distribution between China and Europe (e.g., between Beijing and Vienna, separated by approx 7,600 km), which was then used to secure a video conference.

More things to be followed up.

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