Spring 2022

A Pitt Physics seminar

Abstract: Magnetic skyrmions and topological spin textures have been investigated as possible information carriers in next generation devices. Among the well-studied B20 materials, MnGe is an interesting outlier that has been shown to host a novel three-dimensional hedgehog/anti-hedgehog lattice (HL) with a very short period (~3 nm). Here, we use spin-polarized scanning tunneling microscopy (SP-STM) at low-temperature (~5 K) to directly observe the spin textures present at the surface of an 80 nm MnGe thin film. We find the HL is not...

About Dr. Bahrami: 
Mads Bahrami received his PhD in physical chemistry from Sharif University of Technology. His field of research is the foundation of quantum theory and quantum computation. He did his postdoctoral research in the EU under a Marie Curie fellowship and also in the US at the University of California, Riverside, developing new methods for quantum error correction in noising environment. Mads is currently the director of educational programs at Wolfram Research, and leading the Wolfram quantum team:...

Abstract: The advent of quantum computing has created novel opportunities for the direct simulation of quantum systems on quantum hardware. However, in the near term, quantum devices will possess limited scope due to noise and size limitations. Due in part to these constraints, variational algorithms have gained popularity as a powerful yet economical alternative to traditional digital quantum computation. 

In this talk, I will discuss two variational frameworks, parameterized quantum circuits and tensor networks. For each method I will give an overview followed by...

Abstract: Topologists can differentiate between bagels and pretzels by simply counting holes in each bread. The number of holes, formally described by the Euler characteristic, is a topological invariant insensitive to smooth deformation of the shape and size of an object. In condensed matter physics, we study an analogue of pastry, the Fermi sea. Like bread filled with flour, Fermi sea is filled with electrons, and nature provides a variety of exotic topology, e.g. metal copper has a Fermi sea like a pretzel with 4 handles. In this talk, I will introduce physical...

A CMU/Pitt Colloquium

Abstract: The ability to create arbitrary stacking configurations of layered two-dimensional materials has opened the way to the creation of designer band structures.  Twisted bilayer graphene and graphene on hexagonal boron nitride are two of the simplest examples of such a van der Waals heterostructure where the electronic properties of the composite material can be fundamentally different from either individual material.   These van der Waals heterostructures can be formed using a wide variety of layered materials including...

A Pitt/CMU Colloquium

Abstract: The study of quantum materials has emerged as a rapidly developing field of condensed matter and materials physics. Quantum materials are materials that have properties and exhibit phenomena deeply rooted in the laws of quantum physics, which potentially allows us to exploit these laws for future applications in quantum-based energy and computing technology. Furthermore, in addition to providing a desirable resource, quantum materials also offer unique insight into the fundamental and building blocks of matter and the...