Recently BBC coined a new term "escapees from Taiwan" to describe those high-quality people from Taiwan to Mainland for a better future of their own.  (BBC tried to antagonize Taiwan against China; actually those "escapees" are just talents moving from one place to another in the opposite ends within the same country.)  Prof. Lin Yifu is an example that BBC raised as one of the forerunners in such a movement.  I have talked about Prof. Lin many times in my previous writings; incidentally, now I found a concise report of his biography at: https://www.toutiao.com/a6560233000200569358/

FYI, China Mainland is going to issue a new, quasi-national ID for people of Taiwan who are travelling, studying, and working in Mainland.  In the broadest sense of such a measure, by the time all of us will have become "escapees" if we want to have any connection with Mainland. 

P.S.  I have never regarded Prof. Lin as a traitor or a quisling, ever.  Why not?  Simply because all the things he have done so far are loyal to his country: China, either in Taiwan or in Mainland.