Evelyn Hu, the Tarr-Coyne Professor of Applied Physics and Electrical Engineering at the John A. Paulson School of Engineering and Applied Sciences at Harvard University, delivered the 2020 Mildred S. Dresselhaus Lecture on "Transforming Defects into Opportunities: Leveraging the Nanoscale."
As the “Queen of Carbon”, Millie Dresselhaus’ profound understanding of materials like graphene and carbon nanotubes also recognized new design concepts made possible at the nanoscale. Her work on quantum structures brought dramatic new insights into the long-established field of thermoelectric materials. She understood that it was not only the “perfection” of quantum confinement that could improve materials performance, but also features usually regarded as “imperfections”: the many internal interfaces characteristic of nanostructures that might be used as a means to control and enhance the thermoelectric behaviour.
In tribute to Millie’s contributions, this talk provides another narrative of how materials defects and insights at the nanoscale can be developed into transformative scientific opportunities. There has been recent excitement about the performance of defects (such as vacancies, or missing atoms) in crystalline semiconductors, where the defect, also termed qubit, can manifest optical emission at a variety of wavelengths, distinctively coupled to long spin coherence times. In particular, when defects such as Silicon Vacancies in 4H SiC are integrated within nanoscale optical cavities, there is the possibility for remarkable, controlled output of light from the defect. Moreover, the integrated defect-cavity system can serve as a “nanoscope” into the material, allowing us to learn about the interactions with surrounding defects, ultimately providing broader insights into longer-term quantum coherence.
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The Dresselhaus Lecture series is named in honor of Mildred "Millie" Dresselhaus, a beloved MIT professor whose research helped unlock the mysteries of carbon, the most fundamental of organic elements—earning her the nickname “queen of carbon science.” This annual event recognizes a significant figure in science and engineering from anywhere in the world whose leadership and impact echo Millie’s life, accomplishments, and values.
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