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Theoretical Investigation of Quantum Optical Amplifiers in Quantum Communications

Marjan, Negar | 2020

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  1. Type of Document: M.Sc. Thesis
  2. Language: Farsi
  3. Document No: 52893 (04)
  4. University: Sharif University of Technology
  5. Department: Physics
  6. Advisor(s): Bahrampour, Alireza; Bathaee, Marzieh Sadat
  7. Abstract:
  8. Signal transmission of information on noiseless and lossy channels is an important issue in data transmission. Using the amplifier in the transmission channels is a good solution to help send information on longer channels. In classical communication, information can be coded in the amplitude or phase of the field and an amplifier is responsible for amplifying these parameters. If we consider the conditions ideal and ignore electrical noises, Classical mechanics does not impose any restrictions on the amplification of arbitrary classical signals. Instead, in quantum telecommunications the information encoded on the quadrature of the electromagnetic field are mounted on quantum states, such as coherent or squeezed states, and are transmitted through the quantum channel. These conditions are far more vulnerable to channel noise than classical signals. Consequently, we need an amplifier capable of amplifying an unknown quantum signal without noise. In this thesis, we study the problem of noise amplification of a quantum signal in the context of quantum mechanics. We therefore first study in general terms the limitations that the principles of quantum mechanics apply to the noiseless amplification of quantum signals specifically on coherent states. We then introduce different types of amplifiers, which are divided into two major deterministic and non-deterministic categories. We then focus on the study of a non-deterministic amplifier called quantum state comparison amplifier and the theoretical and practical studies that have been undertaken in recent years. These amplifiers compare weak signal modes with other possible guessing modes can lead to noiseless and probabilistic amplification of the signal. In the final part of the thesis, which is our main work, we show you how to correct wrong guesses with the feeding forward method. As a result, the signal fidelity is amplified and we improve the success probability in amplifying the information signal
  9. Keywords:
  10. Noise ; Signals ; Coherent State Quantum Computation ; Quantum Noise ; Quantum Telecommunication ; Noise Less Amplification ; State Comparison Amplifier

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