WHAT ARE QUANTUM MATERIALS?
These are materials where the extraordinary effects of quantum mechanics give rise to exotic and often incredible properties. While all materials exhibit quantum mechanical properties at some level, 'quantum materials' exhibit unique properties like quantum fluctuations, quantum entanglement, quantum coherence, and topological behavior. 2D materials and van der Waals heterostructures allow us to play with legos at an atomic-scale. These stacked 2D materials or van der Waals heterostructures have generated considerable recent interest as designer photonic and optoelectronic quantum materials. Much like legos, they could stack perfectly or be slightly mismatched (strained) or have strong mismatch effects like Moire periodicity. Each of those scenarios requires specific theory tools and methods that we develop.
The ability to directly fabricate structures with atomic precision suggests a new path toward realizing more resilient quantum devices. Recent experimental work by our collaborators has shown that nanoscale fabrication of 2D material based quantum devices may be able to avoid or reduce common sources of decoherence that plague current solid-state quantum systems. Moire pattern structures formed due to lattice mismatch and rotational misalignment in 2D heterostructures would be particularly rewarding due to the large parameter space of possible structures that exhibit an experimentally tunable length scale (the Moire periodicity). Modulation of carrier, phonon and exciton potentials by the Moire superlattice could potentially localize them and affect the electron-electron and electron-phonon lifetimes as well as quantum transport properties. So far, work in this field has been led by experiments and concomitant simulations. This is where our work comes into the picture! We are developing computational tools and a predictive understanding of quantum materials. Combining the power and possibilities of excited-state and heterostructure engineering with the collective and emergent properties of quantum materials, quantum-matter heterostructures open a new field of materials physics.
ENGINEERING NEW QUANTUM DEFECTS
We have an active effort (and numerous publications) on how to model quantum defects in solids such that we can guide the development of next-generation scalable quantum systems. Through ab initio calculations and new theoretical methods, we are working towards "artificial atoms" with desired quantum properties that advance artificial quantum coherent systems.
Our group currently has an Army Research Office funded MURI (Ab initio Quantum Materials) on design of new quantum emitters in 2D materials.
With colleagues at Oakridge National Lab (ORNL) we are supported by the Department of Energy Basic Energy Sciences QIS grant on "Atom-by-atom design and fabrication of new quantum technologies".
Other ongoing projects include:
- Weyl-semi metals and hydrodynamics in materials (by Jenny Coulter). Here's a recent paper by Jenny Coulter on hydrodynamics in type-II Weyl semimetal WP2, as a function of temperature. We present a new approach to calculate phonon drag in this paper.
- Topological photonics, polaritonics and ultra-low loss plasmonics with new quantum materials. In a recent paper, we predict a new (yet-to-be-synthesized) quantum material, Argentene, that could surpass the optical properties of graphene.