Skyrmion pairing: a topological route to superconductivity

Shubhayu Chatterjee
Monday, January 31, 2022 - 3:30pm

A CMU-Pitt Colloquium

Abstract: Atomically thin Van der Waals materials have emerged as a highly versatile platform to advance our understanding of quantum matter driven by strong electron correlations. Recent experimental breakthroughs in stabilizing few-layered graphene structures with a “magic” relative twist between layers has led to the discovery of a wide variety of correlated states ranging from magnetism to superconductivity. Despite compelling experimental evidence for unconventional superconductivity, the glue which binds electrons into Cooper...

Ayres Freitas, Pitt (Pitt/CMU Colloquium)

Ayres Freitas
Monday, October 4, 2021 - 3:30pm

Precision studies of the Higgs boson -- a window to new discoveries

Abstract: With the discovery of the Higgs boson, the last remaining constituent of the Standard Model of particle physics has been experimentally confirmed. However, the Standard Model does not answer several important questions about fundamental physics: What is the origin of dark matter?

Why is there matter but (almost) no antimatter in the universe? How can we describe gravity and quantum mechanics in a consistent way?

The Higgs boson is fundamentally different...

Michael Hatridge, Pitt (Pitt/CMU Colloquium)

Michael Hatridge
Monday, September 20, 2021 - 3:30pm

Quantum information research with superconducting circuits

Abstract: The long-term objective of quantum information research is to build machines, especially computers, whose internal operations are governed by the rules of quantum, rather than classical, mechanics. Quantum computers, if we can realize them, promise to revolutionize which problems we can solve through computation by exponentially speeding up in the calculation of certain problems.  I will discuss my laboratory’s efforts to build quantum-limited amplifiers based on parametric...

Tae Min Hong, Pitt (Pitt/CMU Colloquium)

Tae Min Hong
Monday, September 13, 2021 - 3:30pm

Higgs boson at the LHC: Addressing open questions in elementary particle physics

Abstract: The Large Hadron Collider at CERN, in Geneva, Switzerland, accelerates protons to the highest energies currently inoperations. A tiny fraction of the collisions, about ten in a trillion, involve the interactions of weak force quanta residing inside the protons. I will discuss how such interactions produce the recently discovered Higgs boson, and how it may serve as a portal to unknown sectors of elementary particles, such as dark matter. I will also describe...

Properties of exciton in strongly quantum confined lead halide perovskite nanocrystals

Dong Hee Son
Wednesday, October 20, 2021 - 4:30pm

A CMU Chemistry seminar

Abstract: Metal halide perovskite nanocrystals with the chemically tunable bandgap and superb optical properties are promising candidates for a number of high performance optoelectronic and photonic applications. The majority of studies on perovskites have focused on the large perovskite nanoparticles in the weak confinement regime, however recent synthetic advances have allowed for the preparation of high quality 0D, 1D, and 2D confined perovskites nanocrystals. The access to the strongly confined quantum dots, nanowires and...

Evan Reed, Stanford (CMU MSE)

Evan Reed
Friday, September 17, 2021 - 12:15pm

Identification of new battery chemistries guided by data science and multi-metric performance objectives
Zoom link will be provided

Abstract: I will discuss our efforts to combine diverse data sets and materials property calculations with physics and intuition to identify new battery chemistries that satisfy a spectrum of desirable performance metrics. Traditional approaches to battery chemistry development involve the identification of one battery component and optimization of one or two of the desired properties of that component. This approach has been a...

Gus Hart, Brigham Young University (CMU MSE)

Gus Hart
Friday, September 10, 2021 - 12:15pm

Building Useful Machine-Learned Interatomic Potentials

Abstract: Interatomic Potentials have long been used for atomistic modeling where the interesting questions are out of reach by first-principles approaches. Traditional empirical potentials are typically fitted to experimental data. They typically have poor general accuracy but are physically well-behaved. On the other hand, machine-learned interatomic potentials are far more expressive than physically motivated interatomic potentials like Lennard-Jones, Stillinger-Weber, Embedded Atom Potentials, etc., but they...

Theoretical Reflections on Quantum Supremacy

Umesh Vazirani
Friday, December 4, 2020 - 3:30pm

Abstract: The recent demonstration of quantum supremacy by Google is a first step towards the era of small to medium scale quantum computers. In this talk I will explain what the experiment accomplished and the theoretical work it is based on, as well as what it did not accomplish and the many theoretical and practical challenges that remain. I will also describe recent breakthroughs in the design of protocols for the testing and benchmarking of quantum computers, a task that has deep computational and philosophical implications. Specifically, this leads to protocols for scalable and...

Heusler alloys for Spin Transport

Paul Crowell
Friday, November 20, 2020 - 12:00pm

Abstract: It has been widely appreciated that Heusler alloys (e.g., Co2MnSi) can be half-metallic, meaning that there is a gap for one spin state at the Fermi level. It is in principal possible to use this feature to generate currents that are 100% spin-polarized. Unfortunately, exploiting this characteristic in real devices, which necessarily include interfaces between dissimilar materials, represents a far greater challenge. This seminar will focus on observations about epitaxial Heusler alloys grown on GaAs and MgO. I will discuss why we are interested in the microwave...

Why and How to Integrate 2D Materials in Future Electronics

Ya-Ping Hsieh, Mario Hofmann
Tuesday, November 17, 2020 - 9:00am

Abstract: 2D materials are atomically thin nanostructures that are considered enabling elements in future electronics due to their unique geometry and exciting physical properties. To realize such applications, however, challenges in materials quality and production have to be addressed. In this talk we will first introduce a novel growth method that can enhance the scale, reliability, and controllability of 2D materials synthesis. Through control of the gas phase kinetics of the chemical vapor deposition process, efficient 2D materials growth could...