My friend, there is no vibration dampening tech on highspeed rail, China or any other country. The "Vibration" you are talking about is not vibration of the train's body, but the vibration of train's movement.
A train wheel is a truncated cone, the diameter is bigger inner side than outer side. Therefore when the train is somehow shifted to one side, say left, the wheel will use bigger diameter on left and smaller diameter on right. By this way, left is a little faster than right, so that the train will go back to the middle and prevented from derailed. Of course, it will go over right a little, than back leftward again... This is the "vibration" generally happens in other high quality railways (low quality railways have a lot of different vibrations of course). There's a kind of device to control this kind of movement that all high speed trains in the world have it. But only China actually controlled it into a near perfect level.
This is because China builds the rail and trains in very high construction standard, like huge base of the rail (mostly strong bridges even over plain ground), very long curve with big radius, use huge digital automatic forge to make the train parts, etc. And China do all these with extreme accuracy.
It's a big achievement with out any doubt, but it has nothing to do with submarine.