Dear all,
I hope you all have had a wonderful Spring semester and get a restful break from classes. This is my semesterly reminder about the QSE teaching requirement. Please think about and plan on how you will fulfill the QSE teaching requirement<https://gsas.harvard.edu/policy/quantum-science-and-engineering>. Note that the requirement is to serve as TF for a minimum of 15 hours per week or a 0.375 FTE TF appointment. Depending on the enrollment in courses, departments may offer TF appointments only in increments of 0.25 FTE, so you may require to serve as TF for more than a semester if your appointment is under 0.375 FTE. If you have any questions about this, please do not hesitate to reach out to me.
In addition, we have a new way to inform us about your TF service. Instead of sending me an email, please fill out this TF service form<https://docs.google.com/forms/d/e/1FAIpQLSfIyD8UdcvQ5Z7ZUDzPixuBM4KZ6-4PE22…> to inform us about your upcoming TF service. This information will help ensure that your TF service is counted towards the QSE teaching requirement and also to ensure that your TF stipend is supplemented to the same level as the RA stipend.
Best,
Nishant
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*Time: Friday 10:00 am - 11:30 am ET, May 10*
*Location: Harvard CMSA G10*
Zoom (Back up only, please join in person):
https://harvard.zoom.us/j/977347126
<https://urldefense.proofpoint.com/v2/url?u=https-3A__harvard.zoom.us_j_9773…>
Password: cmsa
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Welcome Eslam!
please help us on posting.
Eslam Khalaf (Harvard)
*Title*: From quantum Hall to Hubbard physics in twisted bilayer graphene
*Abstract*: Early on it was noticed that twisted bilayer graphene (TBG) has
elements in common with two paradigmatic examples of strongly correlated
physics: Hubbard physics and quantum Hall physics. On the one hand, TBG
hosts flat topological Landau-level-like bands which realize quantum
anomalous Hall states and orbital ferromagnetism under the right
conditions. On the other hand, these bands are characterized by
concentrated charge density and show experimental signs of fluctuating
magnetism, and unconventional superconductivty; all characteristics of
Hubbard-model-like physics. The emergence of fluctuating moments is
particularly surprising, as localized Wannier states do not exist in
topological bands. I will discuss a phenomenological model for the flat
bands in TBG that centers the concentration of charge density and,
relatedly, the concentration of Berry flux. The bands obtained have
excellent quantitative agreement with the Bistritzer-Macdonald model for
realistic parameters. I will show that, rather remarkably, the model hosts
decoupled flavor moments which despite being only power-law delocalized
with infinite localization length, have parametrically small overlap with
each other. I will show how this unifies many of the observations in TBG
and leads to a novel Mott semimetal phase for intermediate temperatures
where moments are thermally disordered but charge fluctuations are mostly
frozen.
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https://cmsa.fas.harvard.edu/events-archive/category/quantum-matter-seminar/
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Harvard University CMSA,
20 Garden Street,
Cambridge, MA 02138
Quantum Colloquium – Prof. Garnet Chan
Wednesday, May 8, 2:00pm
Jefferson 250
Garnet Kin-Lic Chan, Bren Professor of Chemistry, Caltech
“Simulating the quantum world on a classical computer”
Dirac wrote that the laws that govern ordinary matter were known, but that the resulting equations of quantum many-particle systems were too complicated to be soluble. I will describe how, a century later, the situation has very much changed in the classical simulation of molecules and materials. I will draw on examples from our group’s research in the applied physics domain, namely recent work on the simulation of the ground-states of high-temperature superconductors and the modeling of certain kinds of quantum dynamics.
Guest presentation will begin promptly at 2:00 PM
Quantum Colloquium – Prof. Garnet Chan
Wednesday, May 8, 2:00pm
Jefferson 250
Garnet Kin-Lic Chan, Bren Professor of Chemistry, Caltech
“Simulating the quantum world on a classical computer”
Dirac wrote that the laws that govern ordinary matter were known, but that the resulting equations of quantum many-particle systems were too complicated to be soluble. I will describe how, a century later, the situation has very much changed in the classical simulation of molecules and materials. I will draw on examples from our group’s research in the applied physics domain, namely recent work on the simulation of the ground-states of high-temperature superconductors and the modeling of certain kinds of quantum dynamics.
Guest presentation will begin promptly at 2:00 PM
Quantum Colloquium – Prof. Xie Chen
Wednesday, May 1, 1:00pm
Jefferson 250
Xie Chen, Caltech
“Quantum circuit as a lens into quantum phases and phase transitions”
Quantum systems host fascinating phases like superconductivity, quantum Hall, topological order, etc. that have no classical counterpart. Understanding what quantum phases exist and how phase transitions happen between them is the ultimate goal of condensed matter. But this is notoriously hard, especially in systems with strong interactions. We find that the Quantum Circuit, a tool in quantum computation, provides surprisingly useful insight into the many-body entanglement structure of quantum wavefunctions and correspondingly the structure of the quantum phase diagram. In this talk, we start by reviewing how a decade ago defining gapped quantum phases using finite-depth quantum circuits led us to the systematic construction and classification of Symmetry Protected Topological Phases. Recently, we made another breakthrough by realizing that the transition between different gapped phases can be achieved with sequential quantum circuits. This opens the door to the systematic study of defects in quantum systems, their condensation, and the induced phase transitions in strongly interacting systems.
Guest presentation will begin promptly at 1:00 PM
