2d-ion crystals for quantum computing and near-term quantum applications

The development of a general-purpose quantum processor requires the possibility of scaling the device up to large numbers of quantum bits and the realisation of fault-tolerant quantum gate operations between them, ideally with the possibility to carry out gates between arbitrary qubit pairs. In trapped-ion based implementations, quantum gates are typically carried out on sub-ensembles of qubits that are stored in linear strings of ions. These sub-ensembles are subsequently connected by shuttling ions around or using photonic interfaces. To reduce the footprint of such a device, we propose to replace linear strings by two-dimensional ion crystals and directly operate on 100 ion-qubits. Within this application, we will demonstrate the realisation of entangling gate operations between arbitrary ion pairs in a 2d-crystal with fidelities better than 99%. In collaboration with the company Alpine Quantum Technologies (AQT), we will make off-the-shelf 2D ion-crystals available for computational tasks by integrating the traps needed to store the crystals into the quantum computing systems developed by AQT. The control of these first-of-its-kind 2D ion-trap array will be based upon standardised quantum software development kits for this novel computing architecture. The realisation of a universal gate set in a processor with about 100 qubits with all-to-all connectivity will, beyond quantum computation, spearhead novel applications in hybrid digital-analog quantum simulations, quantum metrology and quantum networks.