# IAS High Energy Theory Seminar

## " “Unnecessary” Quantum Critical Points in Condensed Matter and Field Theory"

**Abstract:** Quantum critical points usually separate two distinct phases of matter. Here I will discuss a class of "unnecessary" quantum critical points that lie within a single phase of matter (much like the liquid-gas transition, except that they are continuous) so that there is a path that avoids them. First found in critical non-abelian gauge theories, there are by now a number of simpler examples of such quantum critical points. In this talk, I will focus on the conformal fixed point of massless QED3. I will show that this theory describes an unnecessary quantum critical point living inside the most familiar Neel antiferromagnetic phase of spin-1/2 square lattice magnets.

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Bloomberg Lecture Hall (IAS) & Zoom### Speakers

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This seminar will also be presented** **on Zoom.

https://theias.zoom.us/j/84116605050?pwd=VHV6VkRUM3hkM2dFSlo2QWJiUWtPdz09