Papuchis coached at LSU under Nick Saban before joining Bo Pelini's staff at Nebraska in 2008, spending the past three seasons as defensive coordinator.
Papuchis joins a staff looking to reshape a defense that gave up more points and yards than any team in program history, including allowing school records of 70 points and 789 yards in a loss at East Carolina.
Last month, the Tar Heels hired former Auburn head coach Gene Chizik as its new defensive coordinator. Head coach Larry Fedora says the 36-year-old Papuchis has ''quickly earned a reputation as an outstanding teacher and recruiter.''
Team spokesman Kevin Best says Papuchis' position assignment has yet to be determined.