  For a long time, we thought that only symmetry breaking can give rise to
different phases of matter. If there was no symmetry breaking, there would be
no pattern and it would be featureless. But now we realize that, for quantum
matter at zero temperature, even symmetric disordered liquids can have
features, which give rise to topological phases of quantum matter. Some of the
topological phases are highly entangled (i.e. have topological order), while
others are weakly entangled (i.e. have SPT order). In this article, we will
briefly introduce those new zero-temperature states of matter and their amazing
emergent properties. We will also discuss their significance in unifying some
most basic concepts in nature.
