# Topology of the Fermi sea: ordinary metals as topological materials

### APA

Tam, P.M. (2022). Topology of the Fermi sea: ordinary metals as topological materials. Perimeter Institute. https://pirsa.org/22120022

### MLA

Tam, Pok Man. Topology of the Fermi sea: ordinary metals as topological materials. Perimeter Institute, Dec. 08, 2022, https://pirsa.org/22120022

### BibTex

@misc{ pirsa_22120022, doi = {10.48660/22120022}, url = {https://pirsa.org/22120022}, author = {Tam, Pok Man}, keywords = {Condensed Matter}, language = {en}, title = {Topology of the Fermi sea: ordinary metals as topological materials}, publisher = {Perimeter Institute}, year = {2022}, month = {dec}, note = {PIRSA:22120022 see, \url{https://pirsa.org}} }

Pok Man Tam University of Pennsylvania

## Abstract

It has long been known that the quantum ground state of a metal is characterized by an abstract manifold in the momentum space called the Fermi sea. Fermi sea can be distinguished topologically in much the same way that a ball can be distinguished from a donut by counting the number of holes. The associated topological invariant, i.e. the Euler characteristic (χ_F), serves to classify metals. Here I will survey two recent proposals relating χ_F to experimental observables, namely: (i) equal-time density/number correlations, and (ii) Andreev state transport along a planar Josephson junction. Moreover, from the perspective of quantum information, I will explain how multipartite entanglement in real space probes the Fermi sea topology in momentum space. Our works not only suggest a new connection between topology and entanglement in gapless quantum matters, but also suggest accessible experimental platforms to extract the topology in metals.

Zoom link: https://pitp.zoom.us/j/98944473905?pwd=ak5nVmd4N0pSdXpjOFM0YnFJdnJ4dz09