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Quantum Communications with Structured Light

Maddahi, Mohaddesh | 2020

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  1. Type of Document: M.Sc. Thesis
  2. Language: Farsi
  3. Document No: 52864 (04)
  4. University: Sharif University of Technology
  5. Department: Physics
  6. Advisor(s): Bahrampour, Alireza; Farman, Farnaz
  7. Abstract:
  8. Orbital angular momentum (OAM)and the radial quantum number (p) in infinite-dimensional Hilbert space are two degrees of freedom of light which are associated with the spatial distribution of the electromagnetic field. They are attracting a growing interest for their potential in communication applications ranging from classical communication to fundamental tests of quantum mechanics,quantum communication and quantum cryptography. However, a third party trying to eavesdrop information from communication channel and treat channel security , quantum cryptography or quantum key distribution (QKD) is the secure communication method which is based on the quantum mechanical principles can provides unconditional security for quantum channels. There are several different approaches to quantum key distribution most of which use qubits for encoding information by photon polarization . In this way, the highest bit rate system demonstrated exchanges secure keys at 1 bit per photon. The transverse structure of light provides infinite dimensional Hilbert space, which allows us to encode information in higher dimensional alphabet in quantum communication.In a general bipartite free-space QKD system, misaligning the reference frames of the transmitting and receiving units can increase quantum bit error rate.In this thesis, we have investigated the role of structured light fields as resource for encoding quantum information to increase the capacity of the channel and also its security.Besides, we propose methodes to implement QKD protocols that it does not need for alignment of the transmitting and receiving reference frames in higher levels
  9. Keywords:
  10. Quantum Key Distribution ; Orbital Angular Momentum ; Structured Light ; Free Space Communications ; Radial Quantum Number

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