All-Optical Manipulation and Hyperfine Characterization of Silicon T-centres

Synopsis

With the continued growth of different platforms towards large-scale quantum computation and quantum communication, the development of new systems that provide quantum memory and networked entanglement continues. Spin-photon interfaces are one such group of systems, which aim to combine the best properties of long-lived spin qubits with the ability to transmit information and entanglement through photons. Silicon, a platform with mature microelectronic and nanophotonic fabrication industries, is home to the T-centre, a spin-photon interface with emission at 1326 nm, which is in the telecommunications O-band. The properties of the T-centre must be determined in order to efficiently control T-centre spins for quantum computation and quantum communication applications.

In this thesis we take the first steps towards all-optical control of the T-centre through simulation and experiment. When compared to direct magnetic controls, optical control methods can have higher speeds and improved scalability. We compare different optical control techniques through simulations. To carry out the measurements necessary to eventually achieve optical control, we developed a multi-channel ultra-stable laser system with a linewidth less than 2.6 kHz. We then demonstrate the first steps towards all-optical control of T-centre qubits using T-centre ensembles in isotopically enriched 28Si. First, we measure optical Rabi oscillations, of which Rabi frequencies > 7 MHz were observed. We also measure the ground state hyperfine structure, enabling a determination of the hydrogen spin hyperfine tensor [34]. We find that the zero-field singlet-triplet splittings of the T-centre are 3.482(3) MHz, 3.713(4) MHz, and 4.268(3) MHz. Finally, we report the first observation of optical coherent population trapping with the T-centre. These measurements and simulations identify conditions for full optical control of the T-centre in the context of both 28Si ensembles and single centres in nanophotonic devices.

Keywords: Spin-photon interface; silicon T-centre; optical control; hyperfine; coherent population trapping