A number of recent exciting developments have made the physics of low dimensional systems increasingly important for understanding real materials. In spite of the fact that our world is definitely three dimensional, advances in materials science and fabrication technology have given us systems which effectively have a lower dimension. The properties of such low dimensional solids are often remarkable, unexpected and of great interest both from the point of view of fundamental- and applied physics. Obvious examples are the integer and fractional quantum Hall effects, which are related to the peculiar behavior of quasi two-dimensional layers of charge carriers in certain semiconductor structures. The quantum Hall effects have been vigorously investigated ever since their discoveries in the early 80's, as have the implications of another discovery from this period—scanning tunneling microscopy. As a result of the latter, we now have available a number of sophisticated techniques enabling us not only to resolve individual atoms on a surface but also to manipulate them and potentially to build ultrasmall structures out of atoms.
The beautiful theoretical ideas developed for understanding the quantum Hall effects have inspired work aiming at
understanding other phenomena, such as the high temperature superconductivity of certain ceramic materials, another
remarkable experimental discovery of the last decade. Even though analogies with the quantum Hall effect may turn out to be irrelevant, it is believed that this new class of superconductors owe their outstanding properties to the two-dimensional nature of electron interactions in these materials. In pursuit of the correct theory of high temperature superconductivity many controversial and stimulating ideas have been aired; the question whether it is necessary to go beyond the framework of the conventional Landau Fermi liquid theory is one which is very much in focus of the current debate.
In artificially structured, low-dimensional semiconductor materials the discreteness of electron energy levels gives rise to novel physical phenomena involving active areas whose dimensions approach the de Broglie wavelength of the electron. In addition, the discreteness of the electron charge have lead to observable effects in semiconductor systems. Such effects are also important in systems of ultrasmall metallic tunnel junctions. Indeed, this effect lies at the heart of the "Coulomb blockade" phenomenon and other charging effects of possible relevance for device applications and metrology.
A Nobel Symposium provides an excellent opportunity to bring together a group of outstanding scientists for a stimulating exchange of new ideas and results. The Nobel Symposia are very small meetings and participation is by invitation only. The number of key participants is usually in the range 20–40. In 1991, the 90th anniversary of the first Nobel Prize was celebrated by inviting all previous Nobel laureates to attend the Nobel ceremonies in Stockholm. This gave an excellent opportunity for arranging symposia with topics that would attract several of the Prize winners. Our chosen topic of Low Dimensional Properties of Solids attracted nine Nobel laureates and another forty leading scientists who met in Göteborg for four days before hastening off to the festivities in Stockholm. The program had for practical reasons to be concentrated on certain aspects and we sincerely apologize to all prominent scientists in the field that could not be invited due to space limitations.
These Proceedings contain essentially all the material presented at the Symposium—in invited lectures as well as in contributed posters. A few Symposium contributions which summarized work published elsewhere are exempted. The
papers are organized into three groups:
High Tc superconductivity, in particular the low dimensional aspects
Transport properties of semiconductor nanometer structures
Tunneling in confined geometries, in particular single charge tunneling effects
Many participants gave valuable comments regarding the planning of the Symposium. Special thanks are due to our
program consultants: Ted Geballe, Kostya Likharev, Erik Karlsson, Bengt Lundqvist, Bengt Nagel and Stellan Östlund. Our executive secretary, Ann-Mari Frykestig, made an outstanding job organizing all practical matters. She got good help from many members of the local university community, in particular from Yvonne Steen. Anders Bárány, the editor of Physica Scripta and secretary of the Nobel Committee for Physics, has helped getting these proceedings published with minimum delay.
The Symposium was sponsored by the Nobel Foundation through its Nobel Symposium Fund. The main part of the
lectures were given at Ågrenska Villan, a former merchant mansion that serves as a meetings center for the University of Göteborg under the able management of Kajsa Lindroth. Receptions, that were sponsored by the University of Göteborg, Chalmers University of Technology, and the City of Göteborg, gave the participants possibilities to meet local scientists and industrialists as well as to enjoy chamber music and guided tours of art. A couple of open sessions gave a broader audience a possibility to enjoy reviews of central topics.
We, the organizers, want to express our thanks to sponsors and contributors to this succesful scientific event. We hope that these Proceedings will convey to the reader some of the excitement felt by the participants during the Symposium.