Graduate

Applied Physics/Physics Colloquium presents Using Quantum Tunneling to Discover New Physics in Two-Dimensional Materials

Topic: 
Using Quantum Tunneling to Discover New Physics in Two-Dimensional Materials
Abstract / Description: 

The remarkable physics of two-dimensional (2D) electronic systems has led to 3 sets of Nobel Prizes (1985, 1998, and 2010) and radically changed our understanding of electrons in materials. Experimenters most often probe these systems using electrical transport measurements involving passing an electrical current through the 2D electronic system and measuring voltages appearing across the sample. Such measurements have revealed amazing behaviors such as the quantum Hall effects and the existence of "edge-states" with quantized conductance. However, these and many other measurements have a main limitation in what they tell us about the system: they only have sensitivity to the behavior of electrons near the Fermi energy. Quantum mechanical tunneling, in contrast, can probe electronic states away from the Fermi level. This talk will introduce a contactless tunneling method that utilizes millions of short electrical pulses to induce tunneling currents into and out of 2D electronic systems and yields precise tunneling spectra of 2D system even in regimes where it is electrically insulating. The measurements have revealed remarkable new physics such as: (1) a sharp resonance in tunneling that arises from vibrations of 2D electrons in a "Wigner Crystal"; (2) structure appearing in tunneling spectra that give a direct measurement of the short-range interactions between electrons; (3) measurement and visualization of the 2D energy levels as a function of momentum; (4) observation of polarons and a novel phonon analog of the vacuum Rabi splitting; and (5) measurement of the unusual spin-polarization of the 2D electronic system in magnetic field.


 

Wtr. Qtr. Colloq. committee: A. Linde (Chair), S. Kivelson, B. Lev, S. Zhang
Location: Hewlett Teaching Center, Rm. 201

Date and Time: 
Tuesday, January 22, 2019 - 4:15pm
Venue: 
Hewlett 201

EE380 Computer Systems Colloquium presents Erudite: A Low-Latency, High-Capacity, and High-efficiency Prototype System for Computational Intelligence

Topic: 
Erudite: A Low-Latency, High-Capacity, and High-efficiency Prototype System for Computational Intelligence
Abstract / Description: 

Since the rise of deep learning in 2012, much progress has been made in deep-learning-based AI tasks such as image/video understanding and natural language understanding, as well as GPU/accelerator architectures that greatly improve the training and inference speed for neural-network models. As the industry players race to develop ambitious applications such as self-driving vehicles, cashier-less supermarkets, human-level interactive robot systems, and human intelligence augmentation, major research challenges remain in computational methods as well as hardware/software infrastructures required for these applications to be effective, robust, responsive, accountable and cost-effective. Innovations in scalable iterative solvers and graph algorithms will be needed to achieve these application-level goals but will also impose much higher-level of data storage capacity, access latency, energy efficiency, and processing throughput. In this talk, I will present our recent progress in building highly performant AI task libraries, creating full AI applications, providing AI application development tools, and prototyping the Erudite system at the IBM-Illinois C3SR.

Date and Time: 
Wednesday, January 16, 2019 - 4:30pm
Venue: 
Shriram 104

Applied Physics/Physics Colloquium presents Field Theory, Geometry and Data in Cosmology

Topic: 
Field Theory, Geometry and Data in Cosmology
Abstract / Description: 

Cosmology is a playground for several interesting aspects of theoretical physics. It is a discipline where large quantum effects can change the asymptotics of the spacetime and make it stochastic; where most-recent mathematical techniques can be used to study the fate of very inhomogenous universes, like ours before inflation, and to formulate no-global-singularity theorems; where particle-physics techniques can be applied to predict not only peculiar signals from inflation, but also the distribution of galaxies and extract unprecedented cosmological information from them. I will overview some of these aspects.

Date and Time: 
Tuesday, January 15, 2019 - 4:15pm
Venue: 
Hewlett 201

Biosensor Workshop

Topic: 
Biosensor Workshop
Abstract / Description: 

Research on innovative biosensing devices has potential to improve the health of individuals and populations. Stanford University professors investigate novel approaches to detect biomarkers of illnesses such as sepsis, cancers, influenza, depression and more. Wearable and point-of-care diagnostics could allow testing that is faster, less invasive, more frequent and/or remote from the clinic. Illness may be detected earlier and treated more effectively using data from future biosensors.

Topic of wearable electrochemical devices for noninvasive biosensing
Alberto Salleo, Professor of Materials Science and Engineering

"Real-time biomolecular sensors"
Tom Soh, Professor of Electrical Engineering and of Radiology

Topic of magnetoresistive biosensors
Shan Wang, Professor of Materials Science and Engineering and of Electrical Engineering

 

Date and Time: 
Wednesday, January 16, 2019 - 1:00pm
Venue: 
Clark Center Auditorium

SystemX Seminar presents "Photonic MEMS: Coupling Mechanics & Photonics at the Micro- and Nanoscale"

Topic: 
Photonic MEMS: Coupling Mechanics & Photonics at the Micro- and Nanoscale
Abstract / Description: 

Photonic integrated circuits have seen a dramatic increase in complexity over the past decades, driven by recent applications in datacenter communications and enabled by the availability of standardized mature technology offerings. Among several directions that are currently pursued to enhance functionality and to reduce power consumption in photonic integrated circuits, we exploit in our research mechanical movement of wave-guiding structures at the micro- and nanoscale, motivated by the unique opportunities of access to a strong modulation of the effective index and the possibility to include mechanical latching and thus non-volatile states. In this talk, we will show how we can exploit nano-mechanics in photonic integrated circuits to perform basic operations on-chip, such as phase shifting, attenuation or photonic switching. Due to their small footprint and low insertion loss, such components can be integrated to form large arrays of several thousands of unit cells with outstanding system performance. We will discuss how movable waveguides can be fabricated in dedicated surface micromachining technology or by selective post-processing in a standard silicon photonics platform. We will discuss an experimental demonstrator of a mechanical waveguide latching mechanism, and provide an outlook on the implementation of the concept of large-scale reconfigurable photonic integrated circuits using Silicon Photonic MEMS. 

Date and Time: 
Thursday, January 31, 2019 - 4:30pm
Venue: 
Building 380, Room 380X

SystemX Seminar presents "Beyond Si: III-V and phase change chalcogenide-based microsystems"

Topic: 
Beyond Si: III-V and phase change chalcogenide-based microsystems
Abstract / Description: 

The fields of microelectronics in general and nano/ microelectromechanical systems (N/MEMS) in particular have benefited from many intriguing and in some ways unique solid state and mechanical properties of silicon. Silicon, for many decades now, is the most popular semiconductor for earth and even planetary applications. However, the push to develop devices, sensors, and instruments that have extra high precision, consume low power, and not only survive but work exquisitely in harsh environments has triggered the engineers and scientists to explore other materials as replacements or augmented platforms for Silicon. In this talk, I will go over two specific material systems, gallium nitride, which is the most heavily used piezoelectric semiconductor, and Germanium Telluride, which is a phase change material. I will talk about their unique material properties, ones that are lacking in Silicon, and discuss electronic and optoelectronic devices that we have developed in such material systems benefiting from their unique properties.

Date and Time: 
Thursday, January 24, 2019 - 4:30pm
Venue: 
Building 380, Room 380X

SystemX Seminar presents " Fine-Grain Many-Core Processor Arrays for Efficient and High-Performance Computation"

Topic: 
Fine-Grain Many-Core Processor Arrays for Efficient and High-Performance Computation
Abstract / Description: 


Topic:
Fine-Grain Many-Core Processor Arrays for Efficient and High-Performance Computation
Thursday, January 17, 2019 - 4:30pm to 5:30pm
Venue:
Bldg. 380 Rm. 380X
Speaker:
Prof. Bevan Baas - Electrical and Computer Engineering - UC Davis
Abstract / Description:
The continually-growing number of devices available per chip assures the presence of many processing blocks per die communicating by some type of inter-processor interconnect. It is interesting to consider what the granularity of the processing blocks should be given a fixed amount of die area. The smallest reasonable tile size is on the order of an FPGA's LUT. Between the domains of FPGAs and traditional processors lies a lightly-explored region which we call fine-grain many-core, whose processors: can be programmed by simple traditional programs; typically operate with high throughput and high energy-efficiency; are well suited for deep submicron fabrication technologies; and are well matched to many DSP, multimedia, and embedded workloads, and--somewhat counterintuitively--also to some enterprise and scientific kernels.

The AsAP project has developed fine-grain many-core systems composed of large numbers of programmable reduced-complexity processors with no algorithm-specific hardware and with individual per-processor digitally-tunable clock oscillators operating completely independently with respect to each other (GALS). Due to the independence of the MIMD cores and individual near-optimal oscillator halting, the system operates with a power dissipation that is almost ideally proportional to the system load.

A third generation 32 nm design that integrates 1000 independent programmable processors and 12 memory modules has been designed and fabricated. The processors and memory modules communicate through a reconfigurable full-rate circuit-switched mesh network and a complementary very small area packet router, and they operate to an average maximum clock frequency of 1.78 GHz, which is believed to be the highest clock frequency achieved by a fabricated processor designed in a university. At a supply voltage of 0.9 V, processors operating at an average of 1.24 GHz dissipate 17 mW while issuing one instruction per cycle. At 0.56 V, processors operating at 115 MHz dissipate 0.61 mW resulting in 5.3 pJ/instruction, enabling 1000 100%-active cores to be powered by a single AA battery.

Several dozen DSP and general tasks have been coded plus more complex applications including: AES encryption engines, a full-rate H.264 1080p 30fps HDTV residual encoder, a fully-compliant IEEE 802.11a/11g Wi-Fi wireless LAN baseband transmitter and receiver, a SAR radar engine, a complete first-pass H.264 encoder, convolutional neural networks, large sparse matrix operations, sorting and processing of enterprise data, and others. Power, throughput, and die area results generally compare very well with solutions on existing programmable processors. A C++ compiler and automatic mapping tool greatly simplify programming.

Date and Time: 
Thursday, January 17, 2019 - 4:30pm
Venue: 
Building 380, Room 380X

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