Engineered Quantum States

Project 2:

Novel types of quantum states might lead to fresh approaches to processing, transferring and storing information. We explore various routes to creating, studying and eventually exploiting such states in a variety of systems.

Project leaders: Klaus Ensslin, Thomas Ihn, Ataç Imamoglu, Werner Wegscheider

Members: Klaus Ensslin, Jérôme Faist, Anna Fontcuberta i Morral, Andreas Fuhrer, Thomas Ihn, Ataç Imamoglu, Jelena Klinovaja, Daniel Loss, Alberto Morpurgo, Gian Salis, Christian Schönenberger, Andreas Wallraff, Werner Wegscheider, Vanessa Wood, Dominik Zumbühl

The ability to realize quantum states with tailored and tunable properties is a fundamental ingredient for implementing protocols for quantum information processing and quantum communication. The availability of high-purity materials, sophisticated crystal-growth techniques, and modern fabrication technologies has enabled already the engineering of a range of quantum states. Pushing the frontier in the field further towards ever more complex quantum states that incorporate topological concepts, entanglement and many-body interactions opens up new opportunities for enhanced protocols.

In this project, we exploit new concepts arising from solid-state physics and quantum optics for quantum-state engineering. This includes in particular engineered topological states and entangled ‘dressed’ states between a cavity and a qubit. Our programme comprises developments in material synthesis and the fabrication of nanostructured components, the comprehensive characterisation of the systems created, and the construction of prototype devices. These activities are triggered by, and in turn stimulate, theoretical investigations of novel routes towards quantum engineering and information processing.

Building on our work during the first two phases of NCCR QSIT, we explore a broad variety of material systems and experimental techniques. In two-dimensional electron systems, we establish topological behaviour and explore proximity-induced superconductivity; in one-dimensional nanowires, we experimentally investigate Majorana-based charge qubits and parafermion bound states; and in platforms enabling coherent local coupling between photons and electrons, we realize long-distance coupling of qubits of different types.