From the middle of February until the middle of May 2012, the Center for Interdisciplinary Research (ZiF) of the University of Bielefeld has been the scene for a scientific program with the title indicated above. Philippe Blanchard and Jürg Fröhlich have served as scientific coordinators. Our interest in organizing this program has been aroused by the following developments.
In recent years, there has been major progress in experimentally exploring previously inaccessible realms of the micro-cosmos ? the quantum world ? and in experimentally testing fundamental features of (low-energy) quantum mechanics. This progress relies, on one hand, on the newly acquired ability of experimentalists to manipulate quantum systems, atom by atom, using laser technology, magnetic traps, etc. and to configure atoms into artificial crystals, quantum fluids, Bose-Einstein condensates, etc. On the other hand, it is based on new semi-conductor devices used to realize 2D electron gases exhibiting the fractional quantum Hall effect, 2D and 3D topological insulators, etc.
Thanks to progress in experimental techniques, there are many elegant new experiments testing various somewhat weird aspects of and strange effects in quantum mechanics, such as interference of very large molecules in double-slit experiments, proving the impossibility of hidden-variable theories to describe the quantum world (by exhibiting violations of Bell-type inequalities and verifying predictions of the Kochen-Specker theorem), and illustrating curious consequences of entanglement, quantum teleportation, etc.
Furthermore, many new applications of quantum-mechanical effects in the field of information science, cryptography and computation have been proposed, some of which have actually been implemented in devices. Another related area that has seen much progress in recent years concerns open quantum systems and quantum transport.
All these developments have confronted theorists with numerous challenging problems that have been addressed and, in some instances solved, in recent years. Although quantum mechanics has been with us for more than eighty-five years, they have led to a new surge of interest in the foundations of this theory, which have puzzled physicists ever since its discovery, and in surprising new applications of quantum mechanics that appear to bear strong potential for the future. Yet another direction in Physics that has seen enormous experimental and theoretical progress is the exploration of the early universe, including some of its features suspected to belong to the realm of the quantum. This is the concern of astro-particle physics, which holds enormous promise for the future.
The aim of our program was to gather experimentalists and theorists working in some of the areas described above, in order to review the present state of affairs and to identify interesting and important open problems. Our strategy in pursuing this aim has been to organize two workshops, the first one focusing on the first three topics described above, the second one focusing on some theoretical aspects of the first topic (topological insulators) and the fourth one (open systems and quantum transport). The first workshop began just a week after the start of our program and lasted two weeks. The second one took place three weeks before the end of our program and lasted one week (including Saturday morning). While the first workshop gathered some top-nudge experimentalists and a broad spectrum of theorists, the second one was essentially purely theoretical and technically more demanding. Both of them were extraordinarily successful.
In between the two workshops, we had a mini-program on general relativity and cosmology (the fifth topic described above) featuring two lecturers; we organized lectures by a visitor from the University of Geneva (originally from the Ukraine) specializing in electronic interferometry (the first topic), a mathematician from ETH Zurich (originating from China) working on, among other things, the mathematics of transport theory and friction, a colleague from Göttingen who is a great expert in the foundations of quantum theory and relativistic quantum field theory, as well as by several other visitors working in one of the areas mentioned above, including some PhD students and young researchers. Participants in our program came from many European countries, the Americas and China, the majority from Germany, France and Italy.
Feedback from visitors and participants in our workshops has been uniformly positive. The coordinators received a considerable number of e-mail messages from participants praising the program, which has addressed very topical subjects at just the right time. Some of them confirmed that our program has had a positive impact on their research. Apparently, several scientific papers by various participants, including the coordinators, have been completed in the course of this program.