This award supports theoretical and computational research and education to advance understanding of quantum phase transitions and broaden it beyond the Landau-Ginzburg-Wilson paradigm.
The PI will explore several classes of unconventional quantum phase transitions, focusing on four separate but related areas.
1. Strong-disorder quantum phase transitions: Motivated by experiments on nitrogen-vanadium, cerium-palladium-rhodium, and strontium-calcium ruthenate compounds, the PI aims to develop a theory of rare region effects at itinerant ferromagnetic quantum phase transitions. He will also study the influence of randomness on first-order quantum phase transitions as well as the effects of disorder correlations.
2. Novel phases and transitions in layered systems: The PI will investigate the unusual phases and transitions emerging in randomly and quasi-periodically layered superconductors and superfluids that can be produced in ultracold gases or nano-structured materials.
3. Dynamics and transport at quantum critical points: The PI will study the conductance of superconducting molybdenum germanium and niobium nanowires at the superconductor-metal quantum phase transition. He will also investigate electronic transport in ferromagnetic Griffiths phases.
4 Berry phases in impurity problems and percolation transitions: The PI plans to analyze the effects of Berry phases on the quantum-to-classical mapping of impurity quantum phase transitions as well as their effects on percolation transitions of rotors and spins.
A combination of analytical techniques and computer simulation will be used to carry out the research.
This award also supports efforts to establish a series of "Nobel Prize talks" to be given each fall after the prizes in physics, chemistry and physiology or medicine have been announced. The talks in this series will be coordinated between the Missouri S&T departments of physics, chemistry and biological sciences. They will give elementary introductions into the science behind the prize. These talks will expand the successful series of talks on the physics prize that the PI has organized since 2007. The proposed work will also enhance the research and education infrastructure at Missouri S&T, as the Pegasus computer cluster designed and built and built by the PI becomes a hub of computational research in the Physics Department.
NON- TECHNICAL SUMMARY
This award supports theoretical and computational research and education with the aim to advance understanding of a type of phase transition that occurs in materials at the absolute zero of temperature called a quantum phase transition. Unlike familiar phase transitions, for example the transformation of water to steam, which are driven by thermal fluctuations, quantum phase transitions are driven by quantum mechanical fluctuations, a consequence of the Heisenberg uncertainty principle. Quantum phase transitions are important because their influence can extend to temperatures, possibly as high as room temperature and beyond, and profoundly change the behavior of electrons in materials. This has consequences on the way electrons organize themselves into states of matter, such as magnetism and superconductivity, and other exotic states that have been predicted to occur in materials where electrons interact strongly with each other. The perhaps less familiar state of superconductivity has the unusual feature of being able to conduct electricity without losing energy to dissipation. This leads to potential applications in power transmission. Known superconducting materials only exhibit superconductivity at frigid temperatures, some as high as temperatures where atmospheric gases like oxygen and nitrogen are liquids. A better understanding of quantum critical phenomena may help discover materials that exhibit superconductivity at much higher temperatures. The rigorous description of quantum phase transitions lies outside the standard theory of phase transitions. This research has potential to open new areas in the study of phase transitions. Quantum phase transitions may also have important consequences for efforts to develop quantum computers which are based on the manipulation of quantum mechanical states, and nanoscale technologies involving elements that are some tens of thousands of times smaller than the diameter of a human hair.
This award also supports efforts to establish a series of "Nobel Prize talks" to be given each fall after the prizes in physics, chemistry and physiology or medicine have been announced. The talks in this series will be coordinated between the Missouri S&T departments of physics, chemistry and biological sciences. They will give elementary introductions into the science behind the prize. These talks will expand the successful series of talks on the physics prize that the PI has organized since 2007. The proposed work will also enhance the research and education infrastructure at Missouri S&T, as the Pegasus computer cluster designed and built and built by the PI becomes a hub of computational research in the Physics Department.
