Argonne National Laboratory

Seminar Series

Date Title

Feb. 21, 2018

2:00 pm

Bldg. 440, Room A105/A106

"Deep Learning Applied to Simulation of 2d Materials", Isaac Tamblyn, Security and Discuptive Technologies, National Research Council of Canada. Host:  Pierre Darancet In this talk,

I'll show how we are using Artificial intelligence as a new tool to improve computer models of physical and chemical processes at the nanoscale. In particular, I'll discuss how we show how to rapidly solve the Schrödinger Equation [1], predict phase transitions [2], estimate the strength of chemical bonds [3], provide a confidence level for our predictions [4], and achieve a million times speed up in simulating a nanostructured 2d-material [5].

[1] K. Mills, M. Spanner, I. Tamblyn, Deep learning and the Schrödinger equation Phys. Rev. A 96, 042113 (2017), arXiv:1702.01361
 
[2] K. Mills, I. Tamblyn, Deep neural networks for direct, featureless learning through observation: the case of 2d spin models, arXiv:1706.09779
 
[3] K. Ryczko, K. Mills, I. Luchak, C. Homenick, I. Tamblyn, Convolutional neural networks for atomistic systems, arXiv:1706.09496 
 
[4] K. Mills, I. Tamblyn, Phase space sampling and operator confidence with generative adversarial networks, arXiv:1710.08053
 
[5] I. Luchak, K. Mills, K. Ryczko, A. Domurad, I. Tamblyn, Extensive deep neural networks, arXiv:1708.06686
 
 

Feb. 20, 2018

11:00 am

Bldg. 440, Room A105/A106

"Scattering Studies of a Micron-sized Gold Particle and Average Nanoparticles", Milan K. Sanyal,Saha Institute of Nuclear Physics Kolkata, West Bengal, India.  Host:  Martin Holt

Availability of intense synchrotron sources delivering nano-sized beam should be able to provide us structure, composition and strain profiles within a nanoparticle from averaged information obtained over only few such particles and finally may be even from an individual particle. We shall discuss here few evolving x-ray scattering techniques with the help of three recently studied systems, namely distribution of non-FCC phase in a micron-sized gold particle, shape-evolution in gold nanoparticles grown in nano-pores and extraction of compositional profile of an average III-V semiconductor quantum-dot - the size-tunable photonic material.

Feb. 13, 2018

10:30 am

Bldg. 440, Room A105/A106

"Materials and Processing for Quantum Computing - Ion Traps and Superconductors", David P. Pappas, National Institute of Standards and Technology, Boulder.  Host:  Ilke Arslan.

A brief description and history of quantum computing will be presented. Materials topics relevant to ion traps and superconductors will be presented. For the ion traps, the influence of anomalous surface noise on gate operations will discussed. Progress at NIST to study and mitigate these effects will be presented. These include cleaning, surface spectroscopy and scanned probe microscopy as well as a novel stylus trap to measure noise from proximal surfaces. In the second part of the talk similar topics on superconducting transmons will be discussed. In particular, the effects and mitigation techniques of spurious two-level systems at surfaces and interfaces as well as new scalable techniques for fabricating junctions will be presented.

Feb. 2, 2018

2:00 pm

Bldg. 440, Room A105/A106

"Flexible Electronics Based on Two-Dimensional Materials and Beyond", Xu Zhang, Massachusetts Instittue of Technology. Host:  Daniel Lopez

The success in creating atomically thin and mechanically robust two-dimensional (2D) materials has unveiled new possibilities for next generation of flexible and ubiquitous electronics. One critical distinction between 2D crystals and 3D crystals is that 2D crystals are all-surface materials. Therefore, it is essential to understand how 2D materials interact with their environments and how this interaction impacts their electronic properties. A suite of X-ray techniques is used to investigate how the functionalizing dopants impact the electronic and chemical states of graphene. Based on this study, we develop an effective and non-invasive doping method for graphene through plasma-based chlorination. In the second part of this talk, I will focus on system-level applications of 2D materials-based flexible electronics with a special focus on wireless energy harvesting and communication. In particular, we developed a 2D material-based GHz flexible rectifier as an enabling component for both wireless energy harvesting and RF frequency mixing. It is the first flexible rectifier operating up to the X-band and it fully covers the Wi-Fi channels. By integrating with an antenna, the MoS2-enabled rectenna successfully demonstrates direct energy harvesting of electromagnetic (EM) radiation in the Wi-Fi band and lights up a commercial light-emitting diode (LED) with zero external bias (battery-free).

Feb. 1, 2018

2:00 pm

Bldg. 440, Room A105/A106

"Novel transport characterizations in anisotropic and disordered", Lintao Peng, Northwestern University, Electrical Engineering and Computer Science.  Host:  Nathan Guisinger

New electrical transport techniques are introduced for characterization of exfoliated black phosphorous devices. First, an all-electrical conformal-5-contact method is proposed to determine the crystal orientation of an exfoliated flake. Second, the disorder-related switching transient conductivity, and a microscopic DOS model thereof, are discussed within the framework of dispersive diffusion transport and continuous time random walk. Finally, the observation of a disorder-scaling behavior in gate-dependent conductivity is presented and modeled.

Jan. 24, 2018

3:30 pm

Bldg. 440, Room A105/A106

"Light- and heat-managing nanomaterials for personal health and energy efficience", Po-Chun Hsu, Department of Mechanical Engineering, Stanford University.  Host:  Supratik Guha

Energy and health are the two vital necessities for humans. While energy is indispensable, it also produces greenhouse gas emission and climate change. In the US, 12% of total energy is used for maintaining indoor temperatures, which is the fundamental need for human health. Therefore, it is crucial to reduce the building energy consumption while maintaining thermal comfort. In this talk, I will present several nanomaterials that can manage photons and heat transfer to enhance building energy efficiency and personal health. The first part is the personal thermal management by controlling radiation heat transfer, which contributes 50% of the human body heat dissipation. I will demonstrate infrared-reflective nanowires textile for heating, infrared-transparent nanoporous polyethylene for cooling, and asymmetrical emitter to achieve both heating and cooling. The second part is transparent electrodes and electrochromic smart windows for solar heat gain modulation. Fabricated by electrospinning, the metal nanofiber transparent electrodes with superior electrical and optical properties and durability can improve the speed and cycle life of electrochromic windows.

Jan. 11, 2018

11:00 am

Bldg. 440, Room A105/A106

"There's Plenty of Room in Higher Dimensions - Internal Resonance and Decision Mechanisms in Mechanical Resonators", Axel Eriksson, Chalmers University of Technology, Sweden.  Host:  David Czaplewski. 

To understand how adaptive behavior emerges in living and artificial systems is a major challenge for science. In this talk, I consider something simpler – dead vibrating silicon beams and graphene membranes. I will give a short introduction to nonlinear dynamics of vibrational modes in mechanical resonators. An interesting situation occurs when two vibrational modes have a rational relation between their frequencies – a so called internal resonance. The match in frequency allows for efficient transfer of energy between the two modes. Hence, the internal resonance will strongly affect both the dissipation and the driven response of the resonator. The complex response has similarities with other strongly nonlinear systems such as interacting neurons in the brain. Furthermore, the driven response may exhibit choice mechanisms leading to stochastic switching between different long-term behaviors. In future work, we plan to experimentally control this switching as a means to achieve primitive adaptive behavior in mechanical resonators.