Quantum computation has captured the imagination of many, but has long seemed beyond reach. Casimir groups have played a crucial role in removing obstacles towards an actual scalable design for information storage and manipulation based on quantum systems.
Qubits: Our approach to quantum computation is through solid-state nanofabrication of qubits, as this is one of the most promising avenues for scaling up to many qubits, whether in the form of superconducting circuits (DiCarlo), spins in diamond (Hanson), or spins in semiconductor quantum dots (Vandersypen and Kouwenhoven). The central challenge is to maintain quantum coherence while achieving control of the qubits.
Majorana: Very recently, with seminal contributions from Beenakker’s group (Leiden), it has been suggested that information may be stored indefinitely in the form of Majorana Fermions. Kouwenhoven’s group (Delft) has discovered the first experimental signs of these fermions by coupling a so-called topological insulator with a superconductor in a solid-state device. Equally important is the emission and detection of single photons, as well as the future quantum repeater, all important elements of a future quantum internet (Zwiller group). The national science funding agency FOM and Microsoft co-fund the Leiden-Delft collaboration as leading effort in solid-state quantum information processing.
Quantum oscillations: The groups of Bouwmeester and Oosterkamp (Leiden) and Van der Zant and Steele (Delft) are exploring quantization of mechanical vibration states of macroscopic objects, a phenomenon profoundly connected with the foundations of quantum mechanics. It has been argued that quantum mechanics as we know it should break down for an oscillator of sufficient mass, oscillating at sufficiently large amplitude. In order to test these ideas Bouwmeester’s team aims to bring a mechanical oscillator in quantum superposition with a single photon in an optical cavity.