PHILADELPHIA -- The former chairman of Temple University's physics department has pleaded not guilty to charges he gave U.S. technology secrets to China.
Xi Xiaoxing is an expert on superconductivity. Federal prosecutors say he sought prestigious appointments in China in exchange for providing data on a U.S. firm's device.
The 47-year-old professor appeared in court in Philadelphia Thursday to enter his not guilty plea.
He is free on $100,000 bail but has surrendered his passport. He is a naturalized U.S. citizen born in China.
Xi has retained Washington lawyer Peter Zeidenberg, who successfully defended an Ohio woman in a Chinese spying case.
Zeidenburg vows that Xi will also be exonerated.
He remains a Temple faculty member. He lives with his wife and children in suburban Philadelphia.