The Project Philosophy

The principle philosophy of SOLID is to implement small solid-state pure and hybrid QIP systems on common platforms based on fixed or tunable microwave and optical nanophotonic cavities. As illustrated in the figure below, various types of qubits can be connected to these "hubs": Josephson junctions (JJ), quantum dots (QD), nanowires (NW), and NV centres (NVC) in diamond. For JJ-circuits, a common procedure is to connect several qubits to the same MWC. However, conceptually the approach can immediately be extended to connecting different types of solid-state (as well as other types of) qubits in hybrid devices, opening up new avenues for processing, storage and communication. In the figure, the red links connect qubits with microwave devices (MWC), while blue links connect qubits with nanophotonic optical devices (NPhC). The linked objects represent connections and devices that will be primarily explored within the project. The systems that will be fabricated and explored and the methodologies that will be applied can be found in workpackages.

The hybrid approach that is being followed within SOLID is not only suitable for solid-state qubits but, in principle, also for incorporating microscale ion and atom traps, cold atoms and molecules, as well as Bose Einstein condensates. There is currently no direct link between the microwave (MWC) and optical (NPhC) hubs. A major long-term challenge will be to create indirect links via various qubit realisations making it possible in the future to create functional quantum interfaces.

The scientific outcomes of the project will be:

• The development of meso- and nanoscale solid-state systems to be used as qubits
• The interconnection of these systems using fixed or tunable microwave cavities and optical nanophotonic resonators.
• The development of hybrid systems and devices that open up new perspectives for the processing, storage and communication of quantum information.