What is the shortest trip I can can on a bullet train from Shanghai?

the shortest is the intercity trip between Shanghai South to Jin Shan Wei. you can get off at the second station, Chunshen station. It takes only 9 minutes and costs CNY3. this is more like a trip by subway.
If you want to experience a high-speed rail trip, you can go from Shanghai or Shanghai Hongqiao station to Kunshan. It takes less than 20 minues and costs CNY18.5 for first class and CNY14.5 for second class.