Presumably, you can either print out the QR code or show it on your phone (e.g. the 12306 app is mentioned several times in the article) for the train people to scan.

But, I just read the article again, and noticed that passports are not listed as a valid ID type. Rather, it specifies 外国人永久居留身份证, which is the permanent residence card for foreigners (not to be confused with the 1-5 year residence permits that are attached to work or study permits). In light of the fact that these are still rather uncommon, I'm wondering if it was a typo, or if they are planning on rolling it out more broadly after working out the kinks.

Does anyone have any first hand experience (using passports as ID) yet?