Patrick Ledwith ’19, Pappalardo Fellow

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Area of Physics

Condensed Matter Theory

Research Interests

Patrick is a theoretical physicist who studies quantum many body systems. He is particularly interested in understanding and predicting collective properties that emerge from strongly interacting electrons. He has recently focused on moiré materials, like twisted bilayer graphene at the “magic angle” of 1.1 degrees. These materials often host strongly interacting topological bands. The topology of the band ensures that electrons cannot be localized, which makes exotic correlated motion one of the best ways for electrons to minimize their interaction energy. This correlated motion, in turn, can produce “fractionalized” phases of matter at the macroscale in which the fundamental excitations have electric charge smaller than that of the constituent electrons.

Patrick is also interested in bridging the theoretical gap between strongly correlated electrons in (1) the topological “quantum Hall” setting and (2) the “Mott” setting that is emblematic of high temperature superconductivity and traditionally not topological. He has begun developing new analytical tools for this purpose, with applications to twisted bilayer graphene.

Biographical Sketch

Patrick grew up in North Wales, Pennsylvania in the Philadelphia area. He went to MIT for his undergraduate degree in Physics and Mathematics in 2019. While at MIT he worked with Leonid Levitov on electron hydrodynamics, discovering and elucidating extra-long-lived collective excitations in two dimensional electron gases. He then went to Harvard for his PhD, advised by Asvhin Vishwanath. During his PhD he worked on a variety of topics within moiré materials, including analytical methods for predicting and realizing fractional Chern insulating states.

Selected Publications

• P. Ledwith, J. Dong, A. Vishwanath, and E. Khalaf, Nonlocal Moments in the Chern Bands of Twisted Bilayer Graphene, Aug. 2024. arXiv: 2408.16761.
• P. Ledwith, A. Vishwanath, and D. E. Parker, “Vortexability: A unifying criterion for ideal fractional Chern insulators,” Physical Review B, vol. 108, no. 20, p. 205 144, Nov. 2023.
• T. Devakul, P. Ledwith, L.-Q. Xia, A. Uri, S. C. de la Barrera, P. Jarillo-Herrero, and L. Fu, “Magic-angle helical trilayer graphene,” Science Advances, vol. 9, no. 36, eadi6063, Sep. 2023.
• P. Ledwith, G. Tarnopolsky, E. Khalaf, and A. Vishwanath, “Fractional Chern insulator states in twisted bilayer graphene: An analytical approach,” Physical Review Research, vol. 2, no. 2, p. 023 237, May 2020.
• P. Ledwith, H. Guo, and L. Levitov, “The hierarchy of excitation lifetimes in two-dimensional Fermi gases,” Annals of Physics, vol. 411, p. 167 913, Dec. 2019, issn: 0003-4916.