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This Week at Physics

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Events on Friday, September 30th, 2016

R. G. Herb Condensed Matter Seminar
Engineering light-matter interactions with atom-like systems
Time: 10:00 am
Place: 5310 Chamberlin Hall
Speaker: Jennifer Choy, Draper Laboratory
Abstract: Techniques that utilize photons to probe and manipulate discrete electronic energy levels in atoms have enabled numerous metrology applications, including precise and stable inertial sensors, time and frequency standards, magnetometers, and test-beds of quantum information protocols. Despite the promise of this technology, the electro-optics and vacuum requirements associated with atomic instruments pose a considerable challenge to their implementation outside of the laboratory. This field can greatly benefit from integration with a photonics platform that provides robust and efficient control of photon-atom interactions.
Wide-bandgap semiconductors are candidate material systems for such a photonics platform. Recent advancements in material processing and nanofabrication have made it possible to develop micro- and nano-photonic devices in these “nonstandard” materials. In some cases, crystalline defects can lead to optically active color centers that can be isolated as single quantum systems (“artificial atoms”), with optical and spin properties that are viable for quantum information and quantum sensing.
In this talk, I will provide examples of engineering light-matter interactions with these artificial atoms, focusing on the nitrogen-vacancy center in single-crystal diamond. I will review several devices that enhance color-center emission, including nanowires and gratings that improve excitation and collection efficiencies, as well as resonators that modify spontaneous emission rates. I will summarize the major applications that have been enabled by diamond-based photonic devices. Finally, I will conclude with an overview of other potential photonic platforms (e.g. silicon carbide, titanium dioxide, silicon nitride, III-V materials, and hybrid approaches), and a comparison between photonics with solid-state artificial atoms and real atomic systems.
Host: McDermott
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Physics Department Colloquium
Nuclei and Cosmos
Time: 3:30 pm
Place: 2241 Chamberlin hall
Speaker: Ani Aprahamian, Notre Dame University
Abstract: : The Origin of the Heavy Elements in the Universe was identified as one of the Eleven Unanswered questions in Physics and Astronomy at the beginning of the 21st century. The question in intertwined in the complexities of the cosmos with the properties of nuclei. The universe can and does synthesize the heavy elements but the question regarding the site(s) of the synthesis remains unresolved. My talk will focus on an attempt to use nuclear properties as a tool to perhaps distinguish between two of the popularly proposed sites of compact object mergers and core collapse supernovae. We have just completed a comprehensive sensitivity study of the exotic nuclei that have the largest impact on the rapid neutron capture process (the main mechanism for producing the heavy elements). Our next goal is to measure the masses, decay rates, and neutron capture rates of these very exotic nuclei. Facilities such as FRIB (Facility for Rare Isotope Beams) now in construction at Michigan State University will allow us to reach the presently unreachable nuclei in the laboratory. Studies of nuclei along with the astrophysical messengers from gravitational waves to neutrinos point to a promising solution of at least one of the outstanding open questions.
Host: Baha Balantekin
Video: https://vod.physics.wisc.edu/media/2016_09_30.m4v
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