UBC Theses and Dissertations

UBC Theses Logo

UBC Theses and Dissertations

Modelling photon statistics of cavity QED systems for integrated photonic quantum computing Gitt, Sebastian


Cavity quantum electrodynamic systems hosted in photonic integrated circuits are being explored as a potential platform for realizing quantum computers, owing to their compact size and scalability. The qubits can be encoded in the electronic states of a localized defect centre in some otherwise uniform host material that comprises a microscopic optical cavity. A particular defect centre of much recent interest is the ⁷⁷Se⁺ donor in silicon, which has a dipole-allowed transition at 2.9 μm. The ground state of the transition is split due to a hyperfi ne interaction with the donor's nuclear spin, resulting in long-lived singlet and triplet states, separated by an energy of 6.87 μeV. These two states can be used to encode the states of a qubit. The fundamental building block of the photonic integrated circuit quantum computing platform involves placing the donor in an optical microcavity with a resonance frequency tuned to the transition frequency of only the singlet or triplet state to the excited state. The quantum state of the spin qubit then controls the transmitted and reflected photon statistics of the cavity in such a way that single photon detectors located in waveguides coupled to the qubit-containing cavities can be used to measure and control the spin state of the qubits via projective measurements. To entangle more than one qubit with high fidelity, photon loss must be minimized, a quantum engineering task that requires a rigorous treatment of open quantum systems. In this thesis, we develop a scattering-matrix based formalism to analyze the photon statistics of multiple defect centres embedded in microcavities evanescently coupled to waveguides. This formalism is used to quantify the properties of a single ⁷⁷Se⁺ donor in a photonic crystal cavity with an experimentally-accessible quality factor. More generally, we look at ensembles of atoms in cavities subject to inhomogenous broadening and dipole-dipole interactions. Modelling ensembles of ⁷⁷Se⁺ donors enables us to study and characterize these systems before site-selective single impurity implantation techniques are perfected.

Item Citations and Data


Attribution-NonCommercial-NoDerivatives 4.0 International