QUROPE Quantum Information Processing and Communication in Europe

The ability to engineer materials at the level of single atoms is rapidly becoming an urgent practical requirement as new technologies demand ever smaller devices. However, such a capability also offers profoundly new functionality for molecular-scale devices. The DIAMANT team has pioneered the discovery and development of diamond as a uniquely promising material system for solid-state molecular technologies: Diamond has exceptional optical and magnetic properties that are associated with dopant complexes or solid-state molecules in the diamond lattice.

We propose to develop a novel photon detector for applications in quantum information processing and for general applications in areas where detection of ultra weak photon fluxes is required.

MICROTRAP is a Strep project aimed at developing an EU technology capability in trapped ion micro-structures for application to quantum information science. Much of the recent experimental advances in Quantum information science have been demonstrated in trapped ion systems, and there is significant interest in developing micro-structure trapped ion system architectures which facilitate scalibility whilst maintaining long coherence times.

A system of neutral atoms stored in an optical lattice is a promising candidate for implementing scalable quantum computing. A quantum phase transition can be used to prepare exactly one atom per lattice site, where each atom can be considered as quantum bit. Based on the so-called Mott-Insulator state several schemes for quantum computation have been proposed, including proposals for the creation of entanglement, computation with cluster states and quantum simulations.

The steady progress in the development of superconducting qubits is opening the door towards the implementation of a complex quantum information processor. There is no doubt that single superconducting qubits and even systems with two qubits can provide decoherence times long enough to perform basic quantum algorithms. However, further increase of system complexity is facing the problem of inefficient external room-temperature electronics test beds.

Following our successful assessment project QUELE, we aim with the present proposal at building and operating a universal scalable quantum processor consisting of 3-10 trapped electrons. Confinement will be performed in a Penning trap using a new concept of planar geometry. Ultra-high vacuum conditions will minimize the effect of the environment. The use of static fields is an advantage over rf ion traps because of weaker decoherence effects due to the absence of r.f. heating.

In the recent years, quantum continuous variables (QCV) have emerged as a tool of major importance for developing novel quantum communication and information processing protocols. Encoding quantum continuous information into the quadrature of a quantized light mode or into the collective spin variable of a mesoscopic atomic ensemble has proven to be a very interesting alternative to the standard concept of quantum bit-based processes.

Quantum communication, the transfer of quantum superposition states over long distances, is presently limited to about 200km (both in optical fibre and free space) due to unavoidable photon absorption losses. For this reason, theoretical schemes to extend this distance using “entanglement swapping” and “teleportation” have been established. By concatenating short entanglement swapping sub-sections it is in principle possible to generate entangled (correlated) bits over very long distances with bit rate only limited by the losses in one short section.