There are fundamental rules and prin-ciples setting the limits of physical sys-tems.It triggers an interesting thought-can we break the limits under specific circumstances?A realistic system can only provide limited functionalities be-cause its performance is physically con-strained by some fundamental princi-ples.'Breaking the limit',which usually implies that the capability of a system could be enhanced significantly,is in-triguing in many research areas such as high-precision metrology,imaging and nanophotonics.