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Quantum Communication Part 2

Quantum Communication Part 2. Aditi Harish-Chandra Research Institute, India. Outline. Classical info transmission. Communication. Without security. Quantum state transmission. Communication. Secure Communication. Quantum Cryptography. DC Capacity: Known/Unknown.

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Quantum Communication Part 2

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  1. Quantum Communication Part 2 Aditi Harish-Chandra Research Institute, India

  2. Outline Classical info transmission Communication Without security Quantum state transmission Communication Secure Communication Quantum Cryptography

  3. DC Capacity: Known/Unknown Single Sender – Single Receiver Many Senders – Single Receiver Solved 

  4. Dense Coding Network 3

  5. Distributed DC: Two receivers Bob (B1) Alice (A1) Alice (A2) Bob (B2)

  6. Distributed DC: Two receivers Bob (B1) Alice (A1) i1 LOCC Alice (A2) Bob (B2) i2

  7. Distributed DC: Two receivers Bob (B1) Alice (A1) Alice (A2) Bob (B2)

  8. Distributed DC: Two receivers Bob (B1) Alice (A1) Alice (A2) Bob (B2) Alices send her particles to Bobs

  9. Distributed DC: Two receivers Bob (B1) Bob (B2) Bobs task: gather info abtik by LOCC

  10. Distributed DC: Two receivers Bob (B1) LOCC Bob (B2) Bobs task: gather info abtik by LOCC

  11. Distributed DC: Two receivers C = Max

  12. Distributed DC: Two receivers C = Max Max LOCC Holevo bound Maximizationoverallencodingsi.e.overall {pi, Ui}

  13. Distributed DC: Two receivers C = Max Max LOCC Holevo bound Maximizationoverallencodingsi.e.overall {pi, Ui} Badziag, Horodecki, ASD, Sen, PRL’03

  14. Distributed DC: Two receivers Bruss, D’Ariano, Lewenstein, Macchiavello, ASD, Sen, PRL’ 04 C = Max Max LOCC Holevo bound Maximizationoverallencodingsi.e.overall {pi, Ui}

  15. DC Capacity: Known/Unknown Single Sender – Single Receiver Many Senders – Single Receiver Solved 

  16. DC Capacity: Known/Unknown Single Sender – Single Receiver Many Senders – Single Receiver Solved  Many Senders – Two Receivers

  17. DC Capacity: Known/Unknown Single Sender – Single Receiver Many Senders – Single Receiver Solved  Many Senders – Two Receivers Partially Solved

  18. DC Capacity: Known/Unknown Single Sender – Single Receiver Many Senders – Single Receiver Solved  Many Senders – Two Receivers Partially Solved Many Senders – Many Receivers Not Solved 

  19. Outline Classical info transmission Communication Without security Quantum state transmission Communication Secure Communication Quantum Cryptography

  20. Quantum Dense Coding Task: Classical info transmission Quantum Dense Coding

  21. Quantum Dense Coding Task: Classical info transmission Medium: Quantum State Quantum Dense Coding

  22. Quantum Dense Coding Task: Classical info transmission Medium: Quantum State Task: Quantum state/info transmission Task: quantum state/info transmission Quantum Dense Coding

  23. Quantum Dense Coding Task: Classical info transmission Medium: Quantum State Task: Quantum state/info transmission Medium: Quantum State Quantum Dense Coding

  24. Task: Classical info transmission Medium: Quantum State Task: Quantum state/info transmission Medium: Quantum State Quantum Dense Coding Quantum Teleportation

  25. Quantum Teleportation Bennett, Brassard, Crepeau, Jozsa, Peres, Wootters, PRL 1993

  26. Quantum Teleportation Task: Sending arbitrary quantum state

  27. Quantum Teleportation Task: Sending

  28. Quantum Teleportation Task: Sending

  29. Quantum Teleportation Task: Sending Classical: Infinite communication

  30. Quantum Teleportation Task: Sending Classical: Infinite communication

  31. Quantum Teleportation Bob Alice A in B

  32. Quantum Teleportation Bob Alice A in B Alice performs measurements on “in’’ and A

  33. Quantum Teleportation Bob Alice After measurement A in B

  34. Quantum Teleportation Bob Alice After measurement A in B 2 bits of classical comm. sent by Alice to Bob

  35. Quantum Teleportation Bob Alice After measurement A in B Bob performs unitary

  36. Quantum Teleportation Bob Alice After measurement A in B State is with Bob

  37. Moral Quantum Classical Vs. Task: sending arbitrary quantum state 2 bits of classical comm Infinite classical comm

  38. Moral Quantum Classical Vs. Task: sending arbitrary quantum state 2 bits of classical comm Infinite classical comm

  39. Is it magic?

  40. Is it magic? Of course not!

  41. Is it magic? Ingredient: Quantum Mechanics

  42. Is it magic? Entangled states

  43. What is entanglement? Unentangled/Useless states: Entangled/Useful states:

  44. What is entanglement? Unentangled/Useless states: Entangled/Useful states:

  45. What is entanglement? Unentangled/Useless states: Entangled/Useful states:

  46. Is it just theory?

  47. Experiments

  48. Photons

  49. Photons 143 Km Teleportation

  50. ~100KM

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