When anything is cooled the molecules shake less violently. They contract, right? And when the sea is warmed it expands, right? So why is it that when you put a bottle of water in the freezer, there is less room in the bottle? As though the water has expanded?
Professor Smitha Vishveshwara received her bachelor's degree in physics magna cum laude from Cornell University in 1996, and was supervised in undergraduate research by Carl Franck and David Mermin. She completed her Ph.D in theoretical physics from the University of California, Santa Barbara, in 2002 under the guidance of Matthew Fisher. Her graduate research includes the studies of localization physics in superconductors, Luttinger liquids, and quantum entanglement in carbon nanotubes. She served as a postdoctoral research associate with Paul Goldbart and Tony Leggett from 2002 to 2005, working on tunneling and fractional statistics in quantum Hall systems, Aharonov-Bohm effects in carbon nanotubes, entanglement in spin chairs and critical dynamics in charged superconductors. She joined the department as an assistant professor in August 2005.
Vishveshwara's research interests span a broad range of topics in condensed matter physics, and in particular, in strongly correlated states of matter at scales where quantum phenomena prevail. She maintains strong collaborative ties with experimentalists with regards to research involving cold atomic systems, carbon nanotubes, superconducting proximity effects and topologically ordered states of matter. Some of her research thrusts are as follows:
Co-existence of quantum phases in optical lattices
Interacting bosons confined to a pure lattice can exhibit either Mott insulating behavior, where constituent particles are pinned to lattice sites, or superfluid order, where particles are delocalized over sites. Under certain conditions, trapped bosons in optical lattices can display co-existence of the two phases. Vishveshwara has worked towards understanding various aspects of such a system. She has mapped the spatial profile of the co-existent phases, studied their signatures in spectroscopic and time-of-flight measurements, characterized the excitation spectrum of the system and explored Josephson physics between two superfluids mediated by a Mott insulator.
Anyons in two-dimensional systems
A spectacular feature of two-dimensional interacting systems is the potential existence of ‘topological order’ and associated quantum particles, namely anyons, which possess ‘fractional statistics’ interpolating between the statistics of the well-known fermions and bosons. Vishveshwara has performed extensive studies towards characterizing and detecting Abelian anyons in the fractional quantum Hall (FQH) system. These studies include predictions for statistically dependent partitioning of anyonic current in FQH edge-states, descriptions of two-particle correlators in the FQH bulk and proposals for creating anyonic beam-splitters akin to those that employ photons in other systems . More recently, Vishveshwara has turned to non-Abelian anyons. In light of recent experiments in superconducting strontium ruthenate, she has proposed an interferometry experiment to detect Majorana fermions predicted to exist in such superconductors. She has also studied quench dynamics in a lattice system that exhibits topological order.
Quantum phenomena in one-dimensional systems
Systems that are effectively confined to one dimension, such as carbon nanotubes, etched quantum wires, and mesoscopic rings, demonstrate striking collective phenemona that baffle and contradict the intuition obtained from three-dimensional electronic systems. Vishveshwara has investigated various aspects of such systems induced superconductivity in nanotubes and a related double-gap feature, application of fields on nanotubes as a means of accessing a valley degree of freedom, nanotube quantum dots and charge fractionalization in etched rings.
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