They shared, at least, the science behind gravitational wave transmission and neutrino communications. Possibly other things.
It is not clear to me what their motivation for this was. Although for quite a long period of time both societies appeared to mutually benefit from deterrence and the sharing of information, clearly the Trisolarans were prepared to reneg and return to hostilities if and when the opportunity afforded this. Under that assumption it seemed to be to their disadvantage to share technology with humanity.