Zhu did not say why he killed the woman during the hearing Monday.
Police have said she was decapitated with a kitchen knife while having coffee with the Chinese doctoral student. About seven other people who were in the shop at the time told police the two hadn't been arguing before the attack.
Police received two 911 calls shortly after 7 p.m. on Jan. 21, and were on the scene in a little more than a minute to take Zhu into custody.
The killing stunned a campus that still had vivid memories of the mass slayings in April 2007, when a student gunman shot 32 people and then took his own life. The stabbing was the first slaying on campus since then.
It appeared Yang, who was from Beijing, had met Zhu of Ningbo, China, only recently, Kim Beisecker, the director of Cranwell International Center, has said. Zhu, a doctoral student in agricultural and applied economics, had been assisting her in adjusting to life at Tech, something the 500 Chinese students often do for new members in their community.
Zhu is expected to be sentenced on April 1.