The indictment alleges that the thefts occurred during the past decade from two companies. Hao Zhang worked at Avago Technologies, while Wei Pang, another professor included in the indictment, worked for Skyworks. Here is how the indictment describes the acoustic technologies that the pair allegedly stole:

Surface Acoustic Wave ("SAW") and Bulk Acoustic Wave ("BAW") filters are used in wireless devices to eliminate interference and improve other aspects of device performance.

Film Bulk Acoustic Resonators ("FBAR") are tunable acoustical resonators...often referred to as "filters" because they filter incoming and outgoing wireless signals for wireless devices.... The most common and most profitable application of FBAR technology is as a radio frequency ("RF") filter for mobile phones and other wireless devices.

According to the indictment, Zhang and Pao, together with collaborators, were filing patents for these technologies in China, and their patent applications often emphasized making China "the leading country in the commercial [radio frequency] industry." Radio frequency isn't the most dramatic of military technologies--its no stealth plane or super fast submarine--but its in everything, from tags that track missing uniforms to how aircraft, including unmanned aircraft, still communicate with each other and ground control.

Zhang and others had access to other sensitive technology as well. In a 2006 paper, Zhang wrote about about how different materials work in high tone bulk acoustic resonators; that research was done with funding from DARPA. Why DARPA? It turns out HBARs can also be used to improve military radar.

The indictment also cites a joke in one of the emails Pang sent Zhang in a fascinating lack of subtlety. The joke reads:

"I want to call the company 'clifbaw'." ... When Zhang responded by asking Pang to "explain the inside meaning," Pang replied: "China lift BAW technology - Clifbaw. haha."

That joke, at least, should be a crime. Read the indictment here.