# Orbital Angular Momentum and Spectral Flow in Two Dimensional Chiral Superfluids

### APA

Oshikawa, M. (2015). Orbital Angular Momentum and Spectral Flow in Two Dimensional Chiral Superfluids. Perimeter Institute. https://pirsa.org/15090007

### MLA

Oshikawa, Masaki. Orbital Angular Momentum and Spectral Flow in Two Dimensional Chiral Superfluids. Perimeter Institute, Sep. 29, 2015, https://pirsa.org/15090007

### BibTex

@misc{ pirsa_PIRSA:15090007, doi = {10.48660/15090007}, url = {https://pirsa.org/15090007}, author = {Oshikawa, Masaki}, keywords = {Condensed Matter}, language = {en}, title = {Orbital Angular Momentum and Spectral Flow in Two Dimensional Chiral Superfluids}, publisher = {Perimeter Institute}, year = {2015}, month = {sep}, note = {PIRSA:15090007 see, \url{https://pirsa.org}} }

Masaki Oshikawa University of Tokyo

## Abstract

The orbital angular momentum in a chiral superfluid has posed a paradox for several decades. For example, for the $p+ip$-wave superfluid of $N$ fermions, the total orbital angular momentum should be $N/2$ if all the fermions form Cooper pairs. On the other hand, it appears to be substantially suppressed from $N/2$, considering that only the fermions near the Fermi surface would be affected by the pairing interaction. To resolve the long-standing question, we studied chiral superfluids in a two-dimensional circular well, in terms of a conserved charge and spectral flows. We find that the total orbital angular momentum takes the full value $N/2$ in the chiral $p+ip$-wave superfluid, while it is strongly suppressed in higher-order ($d+id$ etc.) chiral superfluids. This surprising difference is elucidated in terms of edge states.