https://covid19.nj.gov/faqs/nj-information/travel-and-transportation/are-there-travel-restrictions-to-or-from-new-jersey

Please note: school staff and students are still expected to carry out a 14 day quarantine period after travel outside of NJ, NY, PA, CT and DE.

From NJDOH

https://www.nj.gov/health/cd/topics/covid2019_community.shtml#5