It was the third time in as many years that U.S. authorities have made accusations of economic espionage conducted on behalf of China, a sign that the United States is increasingly focused on what it has termed a top national security concern.
Federal prosecutors say Hao Zhang, Wei Pang and Huisui Zhang met at the university and conspired to steal technology from Skyworks Solutions Inc. and Avago technologies soon after graduating in 2006.
A 32-page indictment charging the six with economic espionage and trade secret theft was unsealed after Hao Zhang was arrested Saturday at Los Angeles International Airport after arriving from China to attend a scientific conference. The five others are believed to be in China.
Zhang and the two other USC alums were charged with stealing source code and other proprietary information from chipmakers Avago Technologies Ltd and Skyworks Solutions Inc, where two of them worked.
Avago has headquarters in San Jose, California and Singapore, and Skyworks is based in Woburn, Massachusetts.
Zhang, a former Skyworks employee, and others established a company, ROFS Microsystems, at Tianjin University with secrets stolen from the U.S. firms, prosecutors said.
Tianjin University, one of China's oldest, is located nearly 100 miles southeast of Beijing.
Prosecutors identified the remaining three defendants as Jinping Chen, 41, a professor and a member of the board of directors for ROFS Microsystems; Chong Zhou, 26, a Tianjin University graduate student and design engineer at ROFS Microsystems; and Zhao Gang, 39, who is the general manager of ROFS Microsystems.
According to the indictment, Pang and Zhang met while studying electrical engineering at University of Southern California and took jobs as engineers at Avago and Skyworks, respectively.
Both companies specialize in Film Bulk Acoustic Resonator (FBAR) technology, which is primarily used in mobile devices like cellphones, tablets and GPS devices, but also has military applications.
Between 2006 and 2007, Pang and Zhang hatched a plan to start manufacturing the technology in China and met with Tianjin University officials, prosecutors said. In 2009, both left the U.S. companies to become professors at Tianjin.
If convicted, the defendants could be sentenced to up to 50 years in prison.
U.S. State Department spokesman Jeff Rathke told reporters at a daily briefing that the United States is committed to protecting U.S. companies' trade secrets.
"This is an important issue for the United States," he said.
In March 2014, a California businessman was convicted of stealing DuPont trade secrets to help a state-owned Chinese company develop a white pigment used in a wide range of products and last May five Chinese military officers were accused of hacking into American nuclear, metal and solar companies.
Skyworks and Avago did not immediately respond to requests for comment.
The indictment against the six, which had previously been sealed, was released at a time of intense diplomatic activity between the two major economic powers.
Secretary of State John Kerry was in China at the weekend, partly to prepare for a U.S. visit by Chinese President Xi Jinping later this year. Kerry's trip was overshadowed by concerns over Beijing's maritime ambitions in the South China Sea.
On May 19, 2014, Washington accused five Chinese military officials of having hacked U.S. companies — mainly technology and power companies — to gain trade secrets. China in return accused the U.S. of hypocrisy just days later, when reporters citing documents leaked by former NSA contractor Edward Snowden revealed that the U.S. National Security Agency had breached the servers of Chinese telecom giant Huawei.