An unvaccinated person who travels domestically or internationally should be tested 3-5 days after they return to NJ and quarantine for a full 7 days even with a negative test result. 
If they choose not to get tested, they must quarantine for 10 days. 
A vaccinated person, or someone who has had and recovered from Covid in the past 90 days, does not need to be quarantined, but should be tested 3-5 days after they return to NJ and closely monitor for symptoms.