What is ‘genius visa’, held by Meta scientist denied US re-entry after China visit?

Meta AI scientist Zifan Wang was denied re-entry into the US following a trip to China, despite having worked in the country on O-1 visa. Often dubbed the 'genius visa', O-1 is a US non-immigrant work visa for individuals with extraordinary ability in various fields, including science, business and education. Benedict Cumberbatch and Justin Bieber reportedly worked on O-1 visas.