Passive and active phase manipulation of photons for linear optical quantum information processing

Date

2024-9-03

Author

Başay, Yalın

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Quantum information processing by using photonic qubits is an active research field that shows promise of connecting quantum communication and quantum computation in the same platform. A crucial part of the processing operation is controlling phase of qubits. In this thesis, two ways of phase manipulation are investigated. Firstly, a tunable controlled-phase gate is redesigned to be used in photonic integrated circuits. The phase difference to be applied between the qubits is not hard-coded, and given to the system by an ancilla program qubit during the operation. This provides freedom of deciding the phase during the operation, which leads to more versatile operations. Secondly, a convenient way of adding phase by using photonic crystals is explained and experimental results are presented. The method depends on transition between photonic bands of the crystal. As a result of their band structure, photonic crystals can demonstrate negative effective refractive index for certain wavelengths while having positive one for others. Switching between positive and negative effective refractive indices yields high phase difference of light that can’t be realized by conventional methods. This transition is possible by shifting of band structure, which occurs as a result of slight change in refractive index of material. In the experimental part of this work, silicon-on-insulator with hexagonal lattice of air holes is used and index of silicon is changed by plasma dispersion effect.

Subject Keywords

Linear optical quantum computing, Integrated photonics, Phase modulator, Photonic crystals

URI

https://hdl.handle.net/11511/111412

Collections

Graduate School of Natural and Applied Sciences, Thesis