15 November 2018


Thorvald Wadum Larsen

Thorvald Wadum Larsen

A thesis for the degree of Doctor of Philosophy defended November 2018.

The PhD School of Science, Faculty of Science,  Center for Quantum Devices, Niels Bohr Institute, University of Copenhagen

Charles M. Marcus

Mesoscopic Superconductivity towards Protected Qubits

Several unsolvable problems, such as molecular simulations of drugs, are predicted to be computable with a quantum computer. However, current state-of-the-art quantum bits, qubits, are error-prone making large computations impossible. This thesis presents results from experimental studies of three different approaches towards error-protected qubits based on novel semiconductor nanowires proximitized by an epitaxially grown aluminium shell.

First, we develop gatemons, a semiconductor-based superconducting qubit, as a viable qubit for quantum error correction. Next, we introduce a novel circuit architecture based on the high-transmission of semiconductor Josephson junction to create a protected 0-pi qubit. Finally, we demonstrate a high field compatible superconducting qubit for detection of Majorana states which are predicted to form protected qubits.

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