Spintronics for Quantum-Coherent Control of Materials

Quantum-information science stems from early experimental work on photons and light interactions with atoms and ions trapped in vacuum chambers. However, it is clear that future technological applications will need solid-state systems. Currently, superconducting quantum bit devices are leading this field. However, to scale-up such systems to the millions of quantum bits required for a future quantum computer, it is necessary to dramatically scale down the size of the superconducting qubits and/or utilize different degrees of freedom, such as the spin of electrons, atoms, or molecules. Spins interact weakly with the environment, which is excellent for long coherence times for qubits but causes difficulties in reading and initializing the quantum states. Therefore, we believe that spintronic-derived qubits are highly promising, although little researched. For example, MPI-MSP in collaboration with Daniel Loss’s group at the University of Basel, have proposed a chiral domain wall based qubit. An initial goal will be to explore the quantum mechanical tunneling of single nanoscopic domain walls such as those developed for the most advanced racetrack memory devices. Very early work on DW tunneling was carried out by Gabriel Aeppli in 2001 .

Objectives:
1. Spintronic control of quantum bits on surfaces and in spintronic materials

• Survey of qubit candidates on surfaces by X-ray spectroscopy and cryogenic STXM
• Spintronic control of qubits on surfaces

2. Quantum tunneling of single domain walls

• Demonstration of the quantum tunneling of a single domain wall at cryogenic temperatures