Professor Teunis (Tony) C. Dorlas      





Tony Dorlas was born in Groningen, the Netherlands, in 1955. At an early age he became interested in electronics, but soon discovered that in order to understand it better he had to study more mathematics and physics than was being taught at school. His uncle then gave him an old book on differential and integral calculus by H. A. Lorentz, which he possessed. This book he studied with great interest and it made him change his mind about becoming an electronics engineer. He entered the University of Groningen to study Mathematics and Physics and graduated in both subjects, after which he started working on a Ph.D. under Prof. Nico Hugenholtz. During this time he gave a series of lectures on Constructive Quantum Field Theory and prepared a set of notes (in Dutch) about this subject. His Ph.D. thesis is on a related subject and is entitled On Some Aspects of Renormalisation Group Theory and Hierarchical Models.

He then moved to Dublin, to work as a Scholar (postdoc) at the Dublin Institute for Advanced Studies, where he worked with Prof. John Lewis and Prof. Joe Pule on a variety of models of a boson gas. In this work it was shown that the phenomenon of Bose-Einstein condensation, which is now a very popular subject due to the experimental observation of the effect in 1995, is very subtle and depends on details of the interaction potential. A summary of this work can be found in Large Deviations for Some Models of an Interacting Bose Gas.

It also led to the solution of an old problem: a rigorous proof of the Yang-Yang solution for the thermodynamics of the nonlinear Schroedinger model. This model is exactly soluble with the help of the Bethe Ansatz, which means that one can determine its eigenvalues and eigenfunctions exactly by means of an initial guess. The problem of the completeness of these eigenfunctions was left open, however. This problem was later also solved, after a position as Lecturer in the Mathematics Department of University College of Swansea had been taken up in 1989. The main paper about this work, Orthogonality and Completeness of the Bethe Ansatz Eigenstates of the Nonlinear Schroedinger Model, appeared in 1993. In 1995 a new collaboration was started with Joe Pule and Nicolas Macris from the Ecole Polytechnique of Lausanne, concerning the problem of Anderson localisation in a two-dimensional system with an external magnetic field. This problem is important for the understanding of the (integer) quantum Hall effect, where the existence of Anderson localisation at the edges of the spectral bands is the accepted explanation for the existence of plateaus in the Hall conductance. This work culminated in a paper showing that in fact the lowest Landau bands are completely localised in the case of very strong fields, but with an infinite degeneracy remaining in the centre. It is entitled Characterisation of the Spectrum of the Landau Hamiltonian with Delta Impurities.

From 1995 until 1998 he also supervised a Ph. D. student, Janak R. Wedagedera from Sri Lanka, on the subject of spin glasses and error-correcting codes. This was inspired by a claim of N. Sourlas that spin glasses could be used to construct a code that approximates Shannon's upper bound on the rate of faithful transmission of information. In their paper in PRL, this claim was justified more accurately in a slightly modified form.

In the years 1993 until 1995 lecture courses were given on Statistical Mechanics from a Large Deviation Theory point of view. These were generally well-received and subsequently written up in a textbook entitled Statistical Mechanics. Fundamentals and Model Solutions. It was published by the Institute of Physics in 1999.

In 1999 he accepted a Senior Professorship position at the Dublin Institute for Advanced Studies which he took up in January 2000. After a long process of moving to Dublin, he is now working on a new problem concerning Anderson localisation in collaboration with Joe Pule, and he is giving a set of lectures on Quantum Computing for Trinity students, but open to all. He has also continued research on spin glasses and possible connections with error-correcting codes, in particular in connection with quantum computing, together with Mark Dukes.