In the early 20th century, quantum theory transformed our understanding of matter and materials. The past decade has seen a second quantum revolution in condensed matter physics - the highly entangled quantum matter. In fact, we now see that a myriadof unexpected, and previously disconnected phenomena, such as fractional charge, fractional or non-Abelian statistics, and emergent gauge bosons, have a common root in quantum many-body entanglement.

 

Until 1989, Landau's theory of symmetry breaking was believed to explain all possible orders in matter. However, in studying high Tc superconductors and fractional quantum Hall states, we saw that these phases contain new orders -- topological order that cannot be distinguished by symmetry. More recently, we realized that topological orders are just patterns of long-range entanglement. Long-range entangled qubits can even give rise to gauge bosons and fermions at low energies, suggesting that these fundamental elements of nature may be the result of long-range entanglements. The topological order and long-range entanglements have provided a new conceptual lens, through which we now see that the world of materials is vastly richer than once imagined, and which may in time illuminate the quantum substructure of the universe itself.