by Rahul Jayaraman
Given the exciting news about our very own Prof J. Michael Kosterliz winning the 2016 Nobel Prize in Physics for “theoretical discoveries of topological phase transitions and topological phases of matter,” it seems useful to discuss why exactly his research is relevant. At first read , the description of his research can seem awfully esoteric; however, upon closer inspection, Prof. Kosterlitz’s research proves to have graspable implications for the world around us.
Prof. Kosterlitz’s research focused on phase transitions of these exotic materials, which can be illustrated with a simple analogy – for instance, graphite turning to diamond is a “phase transition,” and graphite and diamond are “phases.” While previous work focused on simply studying analogues to graphite and diamond, Prof. Kosterlitz studied the analogous transition between exotic states of matter.
Conducted in the early 1970s, Prof. Kosterlitz’s research focused on analyzing two-dimensional materials. Two-dimensional materials, also known as “topological” materials, are materials that exist only in two dimensions, rather than the three that we are accustomed to in everyday life. While this may seem a bit strange, it’s not all that surprising – a two-dimensional material is the limiting case of a three-dimensional material when its “height” is 0. Such limiting cases are incredibly interesting to study, since they suggest patterns or behaviors that are not immediately obvious upon studying the object as a whole.
So how do you study something with a height of 0? Prof. Kosterliz’s studies into phase transitions were primarily theoretical and represented a leap in understanding from previous experimental research. Exotic phases of matter, where quantum effects dominate, occur when matter is cooled to temperatures in the tens of Kelvin (between -400 and -300 degrees F – and we thought Providence was cold!) These states had been known and well-studied during the prior couple of decades. However, Prof. Kosterlitz’s work broke new ground since it studied the transitions between these phases, and not the properties of the phases themselves.
So what was Prof. Kosterlitz’s major theory? He posited that vortices in topological states of matter unpair in a phase transition. In simpler terms, pairs of subatomic particles separate at some (extremely cold) critical temperature, causing the material to transition from an ordered to an unordered state, just as the crystalline structure of ice breaks down when it melts and turns into water. In addition, this transition does not break the material’s symmetry, whereas in the ice-water transition, the lattice structure of ice vanishes.
What does this mean, though? How can something that appears so complicated and be applicable in only specific situations relate to our daily lives? One application of studying such transitions is identifying materials that can be turned into superconductors. A superconductor is a material in which all resistance drops to zero as the temperature is lowered, and materials such as these have a wide variety of applications (for instance, some MRI machines use a superconductor). By characterizing these transitions, we will be able to better understand what properties of materials enable them to be a superconductor. Professor Kosterlitz’s research has other applications to modern physics, such as studies into quantum simulations and artificial states of matter.
Despite the fact that most Nobel research appears incredibly complicated and dense, there’s certainly an easy way to break it down – and surprisingly, we see that the research has real-world applications. After all, isn’t relevant research what merits a Nobel Prize?