Without a doubt we live in the information age. Storing and processing information requires a physical device. If this device is a quantum mechanical system, novel possibilities for information science arise: unbreakable cryptographic codes and ultra-fast computational algorithms become possible. In addition, quantum simulations come within reach, finally providing the solution to major unsolved problems in the quantum physics of solids. Exploiting these possibilities requires materials and devices whose quantum states are understood in detail, as these states need to be controlled and manipulated with high accuracy and fidelity. One class of candidates are systems of ultracold atomic matter: collections of only a few atoms that move slowly and can be manipulated precisely with the help of electric or magnetic fields and laser light. A second possibility is to use solid quantum materials in which electrons encode the information as they move through the crystal in a manner that is unusual yet predictable. Examples of such solid state systems are 1-dimensional materials (quantum wires) or 2-dimensional electron systems, as can be realized in graphene (nanoscale chicken wire made of carbon atoms) and –with even greater potential– in a new family of materials known as ‘topological insulators’.
For effective handling of quantum information, an important requirement is fault tolerance: one needs to avoid events where quantum information leaks away or where unwanted switches of a quantum memory occur. One method to achieve fault tolerance is to select a device platform that is, to a high degree, robust against small perturbations. A second strategy is via software: the implementation of fault tolerant algorithms in combination with error correcting codes offer protection against a limited number of errors. A particularly elegant idea is to achieve a kind of intrinsic fault-tolerance through a principle called topological protection.
At IoP-WZI, the Quantum Gases and Quantum Information group (Schreck – recently appointed from IQOQI in Innsbruck, Spreeuw, van Druten, van Linden van den Heuvell) has pioneered experiments with ultracold atoms and is developing novel implementations of information storage and manipulation via ultracold atoms in arrays of magnetic microtraps. The study of ultracold gases in lattices is a promising new direction, which can provide quantum registers and also generate quantum simulators, able to solve as yet intractable problems of central importance to the physics of new materials based on the emergent quantum properties of electrons in the solid state. Schreck, holder of the new chair in Experimental Quantum Physics is about to provide new experimental possibilities at the core of this burgeoning research priority area.
Also at IoP-WZI, the Quantum Electron Matter group (Golden, de Visser, Goedkoop, van Heumen – new tenure track appointment, Dürr – also Senior Scientist and PI at SLAC in Stanford) focuses on just such novel electronic materials including strongly correlated electron systems and topological insulators. Particularly the latter is the focus of great current interest as a possible future platform for encoding quantum information in a topologically protected way.
The ITFA theory group (Caux, Schoutens, Bais, Gritsev – new member of the Delta Institute for Theoretical Physics, Corboz – just appointed) combines expertise covering all fields of quantum matter and quantum information relevant to the cluster. Topological states of matter have a strong tradition, starting from quantum Hall systems through to topological quantum computation extending to contemporary topological insulators. The group additionally encompasses world-leading expertise in the use of exact methods for low-dimensional correlated quantum systems, with important applications in the fields of quantum magnetism, quantum wires, cold atomic gases and quantum information processing.
The ILLC/CWI group (Buhrman, de Wolf, Schaffner – recently appointed within the ILLC/CWI collaboration) is active in the area of fault tolerant quantum computing and addresses multiparty quantum communication complexity, entanglement, quantum algorithms, and quantum cryptography. This latter topic has high valorization potential. The group also works on applications of quantum information to purely classical areas in computer science and mathematics. This so called quantum proof technique does not require the construction of a quantum computing device.
The mathematics research at the KdVI (Opdam, Stokman, Reshetikhin) is concerned with topological quantum field theory in relation to fault tolerant quantum computation and the mathematical description of topological insulators and one-dimensional quantum gases. These quantum field theoretical applications also have a profound impact on several disciplines in pure mathematics, in particular representation theory and knot theory (quantum topology). Vice versa, advances in these latter fields will inspire new techniques in quantum computation.
What makes the QM&QI effort special? Firstly, the cluster translates a wide science span covering different disciplines into a compact consortium, in a single location. Secondly, QM&QI fuses experimental efforts in quantum matter and quantum information with theoretical physics, quantum information theory and mathematical foundations. It is this integrative approach across disciplines that allows the RPA to become an internationally recognized research center.