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PQI Seminar: Dr. Mario Hofmann, Dr. Ya-Ping Hsieh

Dr. Mario Hofmann and Dr. Ya-Ping Hsieh from the National Taiwan University and Academia Sinica gave a talk titled "Why and How to Integrate 2D Materials in Future Electronics" in the Pittsburgh Quantum Institute Fall Seminar series on Nov. 17th, 2020.

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 be achieved in atomically confined conditions. This advance permits the synthesis of 2D materials, such as graphene and TMDCs, at unprecedented scale and at crystalline qualities that rival exfoliated materials. Moreover, synthesis in the van-der-Waals gap of a host 2D material is demonstrated to facilitate a novel 2D crystallization process that yields novel transition-metal monochalcogenides with unexpected thermodynamic properties and finely adjustable thickness. Finally, the atomic length scales in confined growth enable controllable multi-precursor synthesis of diluted magnetic semiconductor 2D materials. The high quality of thus grown materials reveal novel interfacial ordering effects of 2D materials that are fundamentally different from bulk and present both challenges and opportunities towards their integration in electronics. Organization of ionic impurities on high quality graphene was shown to introduce a novel scattering process, that modulates graphene’s mobility by six times and is independent of charge concentration, necessitating improvements in materials’ characterization and handling. On the other hand, ordering effects at 2D materials interfaces can provide routes towards enhanced fabrication and performance of electronic devices. Interaction of graphene surfaces with gaseous adsorbates was shown to stabilize graphene in chemical reactions, permitting atomic-precision lithography approaches for large-scale semiconductor fabrication. Finally, assembly of monolayer water films on graphene under nanomechanical confinement was shown to produce a novel ferroelectric ice phase that can be exploited in mechanical memristive devices.

PQI Seminar: Dr. David Wallace

Dr. Dave Wallace from the University of Pittsburgh gave a talk titled "What is 'Orthodox' Quantum Mechanics?" in the Pittsburgh Quantum Institute Fall Seminar series on Nov. 12th, 2020.

Abstract: What is called "orthodox'' quantum mechanics, as presented in standard foundational discussions, relies on two substantive assumptions --- the projection postulate and the eigenvalue-eigenvector link --- that do not in fact play any part in practical applications of quantum mechanics. I argue for this conclusion on a number of grounds, but primarily on the grounds that the projection postulate fails correctly to account for repeated, continuous and unsharp measurements (all of which are standard in contemporary physics) and that the eigenvalue-eigenvector link implies that virtually all interesting properties are maximally indefinite pretty much always. I present an alternative way of conceptualizing quantum mechanics that does a better job of representing quantum mechanics as it is actually used, and in particular that eliminates use of either the projection postulate or the eigenvalue-eigenvector link, and I reformulate the quantum measurement problem within this new presentation of orthodoxy.

PQI Seminar: Dr. Chris Lirakis

Dr. Chris Lirakis from IBM-Q gave a talk titled "What does it Take to Build a Quantum Computer" in the Pittsburgh Quantum Institute Fall Seminar series on Oct. 1st, 2020.

Abstract: IBM has been working on realizing a quantum computer since the idea first surfaced in 1982. Early instantiations were photon-based and proved that indeed bit like information could be stored in a quantum state. Since then many different modalities have sprung up, Trapped Ions and Superconducting qubits being the most popular. The IBM systems are on the path to error correction. However, we still have a long way to go. The path to success will be paved by wide scale acceptance and training in these using this new computational paradigm. All manner of expertise will be important on the road to success. Beyond the need for experts in quantum computation, the nation will need experts in mechanical engineering, electrical engineering, computer science and other disciplines. During this talk I will show how IBM is using superconducting technology as quantum bits (qubits) and all of the ancillary technology along with notions of the types of problems we wish to solve. The goal is to show how each of this disciplines can help on the path to large scale system.

Pittsburgh Quantum Institute

The Pittsburgh Quantum Institute (PQI) was established in 2012 to help unify and promote research in quantum science and engineering in the Pittsburgh area. PQI members have faculty appointments from Carnegie Mellon University, Duquesne University, and the University of Pittsburgh in physics, chemistry, and engineering disciplines.