Master's Defense: Anton Kovyakh – Københavns Universitet

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Master's Defense: Anton Kovyakh

Scaling Electron Spin Qubit Devices Implemented in GaAs Quantum Dots

Scaling towards multiple qubits is the next major challenge for the field of solid state electron spin qubits. Implementing a solid interconnection mechanism plays a key role in the viability of spin qubits for quantum computation and quantum error correction. A fabrication recipe is developed that allows for creation of arbitrary gate defined quantum systems in two dimensions in GaAs. A number of device designs that allow multiple qubit operation are fabricated. Experimental results from two di↵erent device designs are presented. A linear device with 12 working quantum dots designed for exchange coupling of three resonant exchange only qubits via quantum systems is shown and it’s performance characterized. Operation of exchange only qubits was not possible within the device due to poor performance of the charge sensors and capacitive cross-coupling of the electrostatic gates. A di↵erent device, designed as a flexible platform for implementation of multiple types of spin qubits coupled via a quantum system is also characterized. A tunnel coupled triple quantum dot is configured within the device, and a double quantum dot with the capability for single shot readout is demonstrated. A number of experimental challenges are identified and possible solutions are suggested, together with a few ideas for future experiments within similar systems.