Research in our group focuses on the consequences of quantum mechanics to systems of infinite particles. Many-body quantum physics forms the basis of our understanding of the properties of a growing number of complex materials that are being synthesized in laboratories all over the world. The enormous number of electrons in these artificial materials find themselves in an extreme environment in which they lose their individual character acquiring a collective identity that is governed by the fascinating laws of quantum mechanics. While a theoretical description of our material world is of fundamental interest in our comprehension of nature, predictive powers over such materials are also crucial in the search for the building blocks of future technologies.

Our research program straddles the fields of condensed matter theory, computational physics and materials science. Although our research is theoretical, we have a serious interest in interpreting and predicting the outcome of experiments carried out in a number of research groups worldwide.

Technical Description and Publications

A full technical account of our original research can be found in our published journal articles. Click here for a complete reverse chronological list of publications and pre-prints.

Recently, with Roger Melko and Anders Sandvik, I have written a review article for Annual Reviews of Condensed Matter Physics summarizing the latest developments in the field of numerical simulations of quantum criticality. The science is described at a level that should be accesible to a beginning graduate student and some advanced undergraduates. For a pre-print of this article, click here.

Han Purple is an artificial complex material that was first synthesized more than two millennia ago by Chinese scientists!! It was used to color terracotta sculptures, like the terracotta warriors of Xian. In recent experiments, it has been discovered that Han purple undergoes a zero temperature transition between two distinct states of matter, when subjected to a magnetic field. Remarkably, proximate to the quantum critical point that separates the two phases, Han purple acquires a collective description in terms of a universal quantum field theory. Understating such "universal" properties of materials that transcend their complexity is one of the central goals of my research.
Pictures: (left) Ancient warriors and the Chinese purple. (right) Nature Physics 4, 198-204 (2008)

The devices in the photograph above were made by Kirill Bolotin. They enable scientists to probe the electronic properties of ultra-small pieces of metal called "quantum dots" by connecting the "quantum dots" to the small gold wires in the photograph. (The devices are about the size of a finger nail. The "quantum dots" themselves cannot be seen in the picture: they are often smaller than the 1/100 of a wavelength of visible light and hence cannot be photographed with an optical camera!). One of my research interests is concerned with understanding how the theory of quantum mechanics manifests itself in the unusual electronic properties of these small pieces of metal.
Photo: Blaise Dipersia