16-year-old Petkov, a Bulgarian midfielder, has long been on the club’s radar and has signed a three-year contract.
Speaking to Hearts News about the captures, U20s coach Jon said: “I’m happy to get these guys in and the squad is beginning to take shape.
“We reported back for pre-season training today so the lads got the chance to meet each other, though some have already been and around the club last season.
“It’s now about working hard, achieving peak fitness and undertaking a series of friendly matches before the season starts.”
Main picture - Nikolay Todorov
Second picture - Harry Paton and Marcus Godinho
Third picture - Alex Petkov