TOPOLOGICALLY PROTECTED AND SCALABLE QUANTUM BITS

Our vision is to enable the world of quantum computing through an unprecedented stable and scalable many-qubit system. This platform will allow us to establish important scientific breakthroughs such as the observation of Majorana bound states, which can lead to the new field of non-Abelian many-body physics. A universal quantum computer can be exponentially faster than classical computers for certain scientific and technological applications. This long-awaited innovation can help solve many global challenges of our time related to health, energy and the climate, such as quantum chemistry problems in order to design new medicines, material property prediction for efficient energy storage, big data handling problems, needed for complexity of climate physics. Such a quantum computer has not yet been realized because of qubit fragility and qubit scalability. The output of TOPSQUAD lays the foundation for universal quantum computing with stable and scalable qubits: We will address qubit fragility by creating topological states, which are insensitive to decoherence. We will address qubit scalability by developing waferscale fabrication technology, using CMOS-compatible processes. After TOPSQUAD, existing integrated-circuit technology can then serve to scale up from individual qubits to 100,000s. These two approaches have not been combined within a single system, but our recent results show that we can be the first to address the key challenges: 1. For the first time we will synthesise Ge wires on silicon wafers using scalable CMOS-compatible processes. 2. We will devise an unprecedented silicon system with the required topological properties: Ge wires with a silicon shell. 3. The thin Si shell will suppress metallization, thus avoiding the destruction of topological states by proximity-induced superconductivity, a typically overlooked problem. With this, TOPSQUAD can realize a scalable, CMOS-compatible, topologically protected system.