Seminar

Classical chaotic systems exhibit exponentially diverging trajectories due to small differences in their initial state. The analogous  diagnostic in quantum many-body systems is an exponential growth of  out-of-time-ordered correlation functions (OTOCs). These quantities can  be computed for various models, but their experimental study requires the ability to evolve quantum states backward in time, similar to the  canonical Loschmidt echo measurement. In some simple systems, backward time evolution can be achieved by reversing the sign of the Hamiltonian; however in most interacting many-...

Semiconductor quantum dots (QDs) are nanoscopic crystals that are often called artificial atoms. Charge carriers trapped within them have discrete energy levels in the fashion of single atoms, and they absorb and emit light at discrete wavelengths corresponding to those energy levels. Because of this, in many ways QDs behave like the canonical two-level quantum system, which makes them suitable for experiments involving the quantum nature of light, which is called quantum optics. For this reason and for their potential uses in quantum information applications, QDs attract great scientific...

Over the past decade, first-principles computation has emerged as a powerful complement to experiment in the discovery of new catalysts and materials. In many cases, computation has excelled most in distilling rules for catalyst structure-property relationships in well defined spaces such as bulk metals into descriptors or linear free energy relationships. More development is needed of computational tools for them to show the same promise in emerging catalytic materials such as single-site metal-organic framework catalysts or single atom catalysts that have increased promise of atom...

The field of circuit QED has emerged as a rich platform for both quantum computation and quantum simulation. Lattices of coplanar waveguide (CPW) resonators realize artificial photonic materials in the tight-binding limit. Combined with strong qubit-photon interactions, these systems can be used to study dynamical phase transitions, many-body phenomena, and spin models in driven-dissipative systems. I will show that these waveguide cavities are uniquely deformable and can produce lattices and networks which cannot readily be obtained in other systems, including periodic lattices in a...

Brian J. Anderson, Ph.D., is director of the U.S. Department of Energy’s (DOE) National Energy Technology Laboratory (NETL). Anderson manages the complete NETL complex, including delivery and execution of the Laboratory’s mission, and national programs in fossil energy. Anderson came to NETL from West Virginia University (WVU) where he served as the director of the WVU Energy Institute. He has a long history of collaboration with NETL and other DOE national laboratories. He served NETL as the coordinator of the International Methane Hydrate Reservoir Simulator Code Comparison study and in...

In the race to show quantum advantage, early Noisy Intermediate-Scale Quantum (NISQ) devices must be compared to the state-of-the-art classical technology currently available. At the Quantum Artificial Intelligence Lab (QuAIL) at NASA Ames, we are continuously developing new classical algorithms to benchmark/validate quantum hardware and to raise the bar to claim quantum advantage. In my talk, I will present our optimized classical simulator for large quantum circuits, including numerical simulations of the Google Bristlecone quantum processing unit.

Trapped ions are one of the leading candidates for realizing practically useful quantum computers. Introduction of advanced integration technologies to this traditional atomic physics research has provided an opportunity to convert a complex atomic physics experiment into a stand-alone programmable quantum computer. In this presentation, I will discuss the new enabling technologies that changes the perception of a trapped ion system as a scalable quantum computer, and the concrete progress made to date in this endeavor. I will also discuss potential application areas where quantum...

Publishing the results of one’s research is an integral part of the scientific process, yet scholarly journals are often seen as black boxes by researchers. What happens to a paper after it is submitted? Who is deciding on its fate? What is the role of the journal editor and the editorial office? How does the peer-review process work, and are its core principles still relevant in today’s changing publishing landscape? 
In this talk I will discuss these questions in an attempt to de-mystify the peer review process from an editor's perspective, and provide advice for getting your...

This presentation will discuss the applications of the phase-field method to understanding and discovering new mesoscale polar states that might emerge from nanoscale ferroelectric heterostructures subject to different mechanical and electric boundary conditions. As an example, the determination of thermodynamic conditions and geometric length scales leading to the formation of ordered polar vortex lattice as well as mixed states of regular domains and vortices in ferroelectric superlattices of PbTiO 3 /SrTiO 3 using phase-field simulations and analytical theory will be presented. Switching of these vortex lattice states might produce other transient polar states such as polar skyrmions. It is shown that the stability of these vortex lattices involves an intimate competition between long-range electrostatic, long-range elastic,
and short-range polarization gradient-related interactions leading to both an upper- and a lower- bound to the length scale at which these states can be observed. We further predicted the periodicity phase diagrams that show excellent agreements with experimental observations by collaborators.