Nielsen, 25, of Palo Alto, was traveling south on Middlefield Road at about 12:50 a.m. Saturday when he lost control of his car, Palo Alto police said.
The car struck a sign on the west side of the street, then slammed into a tree and ricocheted off a parked vehicle before coming to rest in the front yard of a home near the intersection of Middlefield Road and Hawthorne Avenue, police said.
Officers arrived and found Nielsen, who was alone in his car, suffering from serious injuries. He was pronounced dead at the scene.
The cause of the crash remains under investigation, according to police.
Nielsen, originally from Denmark, was studying nanotechnology at Stanford, according to his website.