Quantum information transfer between hole spins and topological states

ended

The promise of universal quantum computation stems from the remarkable behaviour of quantum states and the challenge is to gain control over their fragile nature. In topological quantum computation, information can be encoded nonlocally on Majorana states to provide inherent protection against noise, but operation is restricted to the trivial Clifford group. Spins in quantum dots do provide universal logic, but interactions are short-ranged. I propose to study the question whether these platforms can be united to overcome their limitations as a path toward large-scale quantum computation. The grand goal of this project is, therefore, to coherently transfer quantum information between spin and topological qubits. Our quantum material of choice is germanium, which can exhibit strong spin-orbit coupling, can provide long quantum coherence for single spins, and can make ohmic contacts to superconductors for hybrid superconductor-semiconductor systems. We will use two-dimensional germanium hetero structures and fabricate superconducting quantum dot devices. Qubits defined on the spin states of single holes will be electrically driven using the spin-orbit interaction and coupled through the exchange interaction. On linear chains of quantum dots we will pursue topological superconductivity, which we will consequently integrate in the spin qubit platform. We will then study their interaction to demonstrate controllable transfer of quantum information between hole spin and Majorana states. This research is presently at a fundamental stage and is thereby bound to produce exciting results where new physics may arise. The choice of the materials platform and its compatibility with semiconductor manufacturing promises for a successful adoption as building block for future quantum technology. Our long-term dream is to create a powerful platform where complex and emerging systems can be created, simulated, and computed to advance our general understanding of physics.