Nonreciprocal devices such as isolators and circulators are key enabling technologies for communication systems, both at microwave and optical frequencies. While nonreciprocal devices based on magnetic effects are ava...
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We present a simple metasurface-inspired planar focusing collector for concentrated solar power. Fabrication is achieved using two-photon lithography, and subsequent nanoimprint lithography tests for scalability. Opti...
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Gamma-ray bursts (GRBs) are the most energetic phenomena in the Universe. Many aspects of GRB physics are still under debate, such as the origin of their gamma-ray emission above the GeV energy range. In 2019, MAGIC d...
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We study two-dimensional hexagonal photonic lattices of silicon Mie resonators with a topological optical band structure in the visible spectral range. We use 30 keV electrons focused to nanoscale spots to map the loc...
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We study two-dimensional hexagonal photonic lattices of silicon Mie resonators with a topological optical band structure in the visible spectral range. We use 30 keV electrons focused to nanoscale spots to map the local optical density of states in topological photonic lattices with deeply subwavelength resolution. By slightly shrinking or expanding the unit cell, we form hexagonal superstructures and observe the opening of a band gap and a splitting of the double-degenerate Dirac cones, which correspond to topologically trivial and nontrivial phases. Optical transmission spectroscopy shows evidence of topological edge states at the domain walls between topological and trivial lattices.
KAGRA is a 3-km interferometric gravitational wave telescope located in the Kamioka mine in Japan. It is the first km-class gravitational wave telescope constructed underground to reduce seismic noise, and the first k...
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The two-dimensional conducting gas (2DCG) that forms at the interface between LaAlO3 (LAO) and SrTiO3 (STO) has been widely studied due to the multitude of in situ tunable phenomena that exist at the interface. Recent...
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The two-dimensional conducting gas (2DCG) that forms at the interface between LaAlO3 (LAO) and SrTiO3 (STO) has been widely studied due to the multitude of in situ tunable phenomena that exist at the interface. Recently it has been shown that nearly every property of the 2DEG that forms at the interface of (111) oriented LAO/STO is strongly anisotropic with respect to the in-plane crystal direction. This in-plane rotational symmetry breaking points to the existence of an electronic nematic phase at the interface that can be modified by an in situ electrostatic back-gate potential. Here we show that the onset temperature of the anisotropy in the longitudinal resistance is T≈22K, which does not match up with any known structural transition, and coincides with the onset of anisotropy in the Hall response of the system. Furthermore, below 22 K, charge transport is activated in nature with different activation energies along the two in-plane crystal directions. Such a response implies that the band edges along the two directions are different and provides further evidence of an electronic nematic state at the interface.
We report measurements of the superconducting properties of the two-dimensional (2D) gas that forms at the interface between LaAlO3 (LAO) and SrTiO3 (STO) in the (111) crystal orientation, a system that permits in sit...
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We report measurements of the superconducting properties of the two-dimensional (2D) gas that forms at the interface between LaAlO3 (LAO) and SrTiO3 (STO) in the (111) crystal orientation, a system that permits in situ tuning of carrier density and disorder by means of a back-gate voltage Vg. Like the (001) oriented LAO/STO interface, superconductivity at the (111) LAO/STO interface can be tuned by Vg. The 2D superconductivity in these (111) LAO/STO samples shows an in-plane anisotropy, being different along different interface crystal directions, and “remembers” the disorder landscape at which they are cooled through the superconducting transition. The low energy scale and other characteristics of this memory effect distinguish it from charge-trapping effects previously observed in (001) interface samples.
The NSF-funded Redshirt in engineering Consortium was formed in 2016 with the goal of enhancing the ability of academically talented but underprepared students coming from low-income backgrounds to successfully gradua...
The NSF-funded Redshirt in engineering Consortium was formed in 2016 with the goal of enhancing the ability of academically talented but underprepared students coming from low-income backgrounds to successfully graduate with engineering degrees. The Consortium takes its name from the practice of redshirting in college athletics, with the idea of providing an extra year and support to help promising engineering students complete a bachelor's degree. The Consortium builds on the success of three existing "academic redshirt" programs and expands the model to three new schools. The Existing Redshirt Institutions (ERIs) help mentor and train the new Student Success Partners (SSPs), and SSPs contribute their unique expertise to help ERIs improve existing Redshirt programs. The Redshirt model consists of seven main programmatic components aimed at improving the engagement, retention, and graduation of students underrepresented in engineering. These components include: "intrusive" academic advising and support services, an intensive first-year academic curriculum, community-building (including pre-matriculation summer programs), career awareness and vision, faculty mentorship, NSF S-STEM scholarships, and second-year support. Successful implementation of these activities is intended to produce two main long-term outcomes: a six-year graduation rate of 60%-75% for Redshirt students, and increased rates of enrollment and graduation of Pell-eligible, URM, and women students in engineering at participating universities. In the first year of the grant (AY 16-17), SSPs developed their own Redshirt programs, hired and trained staff, and got their programs off the ground. ERIs implemented faculty mentorship programs and expanded support to Redshirt students into their sophomore year. In the second year (AY 17-18), Redshirt programs were expanded at the ERIs while SSPs welcomed their first cohorts of Redshirt students. This Work in Progress paper describes the Redshirt programs at e
Machine learning is a modern approach to problem-solving and task automation. In particular, machine learning is concerned with the development and applications of algorithms that can recognize patterns in data and us...
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