Applied Physics / Physics Colloquium

Applied Physics/Physics Colloquium presents "TTbar Deformations, S-matrix, and Density of States"

Topic: 
TTbar Deformations, S-matrix, and Density of States
Abstract / Description: 

Theories in two space-time dimensions provide playground for exploring geometry of the "Theory Space" - the collection of all quantum field theories. Recently introduced "TTbar deformations" of 2D quantum field theories bring insight into the structure of that space. These are special deformations, "irrelevant" in the renormalization group sense and thus likely altering the local structure of the theory. At the same time, the TTbar deformations generate robust and even solvable theories. Of special interest are the deformations of integrable field theories, where they can be related to deformations of the associated factorizable S-matrix, and the theory can be treated using the powerful tool of the Thermodynamic Bethe ansatz. Preliminary results suggest that the deformed theories typically develop Hagedorn-like density of states, similar to that in the string theories.

Date and Time: 
Tuesday, March 16, 2021 - 4:30pm

Applied Physics/Physics Colloquium presents "The magic of moiré quantum matter"

Topic: 
The magic of moiré quantum matter
Abstract / Description: 

The understanding of strongly-correlated quantum matter has challenged physicists for decades. The discovery three years ago of correlated phases and superconductivity in magic angle twisted bilayer graphene led to the emergence of a new materials platform to investigate strongly correlated physics, namely moiré quantum matter. These systems exhibit a plethora of quantum phases, such as correlated insulators, superconductivity, magnetism, Chern insulators, and more. In this talk I will review some of the recent advances in the field, focusing on the newest generation of moiré quantum systems, where correlated physics, superconductivity, and other fascinating phases can be studied with unprecedented tunability. I will end the talk with an outlook of some exciting directions in this emerging field.

Date and Time: 
Tuesday, March 9, 2021 - 4:30pm

Applied Physics/Physics Colloquium presents "Active Topology"

Topic: 
Active Topology
Abstract / Description: 

Topology plays a key role in condensed matter physics, underlying much of our understanding of equilibrium matter in terms of defects in ordered media and topologically protected states. In active systems – collections of entities that consume energy to generate their own motion and forces – topological phenomena can take on new and surprising roles. I will describe some of these behaviors focusing on liquid-crystalline active matter in two dimensions, specifically active nematic liquid crystals, where defects become motile particles, drive spatio-temporally chaotic flows, and can themselves organize in emergent ordered states.

Date and Time: 
Tuesday, February 16, 2021 - 4:30pm

Applied Physics/Physics Colloquium presents "Getting to a Fusion Pilot Plant"

Topic: 
Getting to a Fusion Pilot Plant
Abstract / Description: 

One hundred years ago Arthur Stanley Eddington conjectured that stars are powered by fusion reactions and speculated that one day humans would generate power by fusion. Not yet. However, private capital is flooding into fusion research driven by the lure of fusion's promise of sustainable "firm" power and optimism about new technologies. I will discuss the benefits of these technologies including high temperature superconducting magnets, permanent magnets and liquid metal systems. I will also discuss the advances in understanding the physics of confined plasmas and the growing efforts to find optimal fusion configurations. There is increasing confidence that, with these advances, an electricity producing Fusion Pilot Plant could be operational before the middle of the century. The fusion community is calling for a concentrated effort to design such a plant.

Date and Time: 
Tuesday, February 9, 2021 - 4:30pm

Applied Physics/Physics Colloquium presents "Searching for Axion Dark Matter Below 1 micro-eV: the Dark Matter Radio"

Topic: 
Searching for Axion Dark Matter Below 1 micro-eV: the Dark Matter Radio
Abstract / Description: 

One of the most enduring mysteries in particle physics is the nature of the non-baryonic dark matter that makes up 85% of the matter in the universe. The QCD axion, originally proposed as a solution to the strong CP problem in QCD, is one of the most strongly motivated candidates for dark matter. In this talk, I will describe the search for QCD axion dark matter with mass below ~1 micro-eV. I will discuss fundamental limits on searches for QCD axion dark matter coupled to electromagnetism, subject to the Standard Quantum Limit, and the Dark Matter Radio, an optimized electromagnetic experiment to probe the QCD axion. I will highlight the role of quantum sensors in completing this search.

Date and Time: 
Tuesday, February 2, 2021 - 4:30pm

AP483 Optics & Electronics Seminar presents "Large Scale Micro-/nano-photonic Materials for Energy and Sustainability"

Topic: 
Large Scale Micro-/nano-photonic Materials for Energy and Sustainability
Abstract / Description: 

Micro/nano-structured materials offer significantly new opportunities for high efficiency devices and systems for energy harvesting, conversion and storage. There is, however, a tremendous gap between the proof-of-principle demonstrations at small scale and the intrinsically large scale real-world energy systems and sustainable applications. In this talk, I will give an overview of our research and, more specifically, present our recent development on how judiciously structured photonic materials address the challenge of the tremendous power hungry for space cooling and promote photosynthesis and crop yield in greenhouses.

Date and Time: 
Monday, March 15, 2021 - 12:00pm

AP483 Optics & Electronics Seminar presents "My Experiences and Science at the ISS"

Topic: 
My Experiences and Science at the ISS
Abstract / Description: 

Ellen Ochoa will describe her career at NASA as the first Hispanic female astronaut, a veteran of four space shuttle missions, and Director of NASA's Johnson Space Center. She will focus on building and operating the International Space Station and show a video that chronicles one of her missions to the station as well as its current configuration.


Ellen Ochoa, American engineer, former astronaut and former director of the Johnson Space Center

Date and Time: 
Monday, March 8, 2021 - 4:15pm

AP483 Optics & Electronics Seminar presents "Grating Based Differential Phase Contrast X-ray Imaging and Recent Applications to Medical Imaging"

Topic: 
Grating Based Differential Phase Contrast X-ray Imaging and Recent Applications to Medical Imaging
Abstract / Description: 

When we think of X-ray imaging, we imagine a photon view as particles are absorbed or scattered in materials. This provides the imaging contrast in many important applications such as dental, chest X-rays, airport scanners. The application of X-ray diffraction gratings enables additional contrast modalities using conventional off-the-shelf X-ray sources. Specifically, the differential phase contrast mode can provide direct access to electron density, and the dark field (fringe visibility) contrast can give texture details well below the resolution limit of the detector – opening the door to exciting imaging possibilities, for example, in lung imaging. The standard Grating Based X-ray Phase Contrast Imaging (GBXPCI) technique uses three gratings G0, G1, G2. The first grating G0 provides the partial coherence needed for X-ray interference; the second grating G1 provides the interference of waves that generates a spatially modulated set of fringes at some distance away; the final grating G2 provides the means to interrogate the fringes before the detector. We will review the basic theory, implementation challenges, and some recent developments in literature.

Date and Time: 
Monday, March 1, 2021 - 4:15pm

AP483 Optics & Electronics Seminar: Continuous measurements of biomolecules in live subjects

Topic: 
Continuous measurements of biomolecules in live subjects
Abstract / Description: 

A biosensor capable of continuously measuring specific molecules in vivo would provide a valuable window into patients' health status and their response to therapeutics. Unfortunately, continuous, real-time molecular measurement is currently limited to a handful of analytes (i.e. glucose and oxygen) and these sensors cannot be generalized to measure other analytes. In this talk, we will present a biosensor technology that can be generalized to measure a wide range of biomolecules in living subjects. To achieve this, we develop synthetic antibodies (aptamers) that change its structure upon binding to its target analyte and produce an electrochemical current or emit light. Our real-time biosensor requires no exogenous reagents and can be readily reconfigured to measure different target analytes by exchanging the aptamer probes in a modular manner. Using our real-time biosensor, we demonstrate the first closed loop feedback control of drug concentration in live animals and discuss potential applications of this technology. Finally, we will discuss methods for generating the aptamer probes which are at the heart of this biosensor technology.


This seminar is sponsored by the Department of Applied Physics and the Ginzton Laboratory

Date and Time: 
Monday, February 22, 2021 - 12:00pm

AP483 Optics & Electronics Seminar presents "A Photonics Perspective on Data Center Interconnects"

Topic: 
A Photonics Perspective on Data Center Interconnects
Abstract / Description: 

The optical networks interconnecting datacenters (DCI) have grown the last decade more than any other transport network and have motivated the evolution of the original Internet architecture and of the global fiber infrastructure [1, 2, 3]. The current growth is also projected to continue strong by at least 2 more orders of magnitude [3, 4], placing DCI at the frontier of optical fiber communications. This presentation offers an industry perspective on DCI-motivated innovations and challenges in optical systems and photonics technology. Notably, photonic integration combined with coherent WDM and advancements in DSP and Moore's law, is enabling current DCI systems to operate ever closer to the fiber Shannon limit by exceeding 6 b/s/Hz spectral-efficiency in transatlantic deployments or reaching 25 Gb/s per Watt power-efficiency in metro DCI 400GE pluggable coherent WDM transceivers [1, 3].

1. L. Paraschis et al "Innovations in Inter Data Center Transport Networks", Chapter 15 (pp. 673 - 718) in Optical Fiber
Telecommunications VII, Edited by Alan E. Willner, Elsevier, ISBN 978-0128165027 (2019).
2. L. Paraschis, "Advancements in Metro Regional and Core Transport Network Architectures for the Next-Generation
Internet", Chapter 18 (pp. 793–817) in Optical Fiber Telecommunications VI Volume B, Systems and Networks, Edited by
Ivan Kaminow, Tingye Li, Alan E. Willner, Elsevier, ISBN 978-0123969606 (2016).
3. U. Holzle, "A Ubiquitous Cloud Requires a Transparent Network", IEEE/OSA Conference on Optical Fiber Communications
(OFC), Plenary (2017), and V. Vusirikala, "SDN Enabled Programmable, Dynamic Optical Layer", European Conference on
Communications (ECOC), Plenary (2017).
4. James Hamilton, "How Many Data Centers Needed World-Wide", https://perspectives.mvdirona.com/2017/04/how- manydata-centers-needed-world-wide (last accessed 2021/01/24).

Date and Time: 
Monday, February 8, 2021 - 12:00pm

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