Physics

Prof. Subir Sachdev
Harvard University

The powerful new idea of topological order has significantly advanced
our understanding of the phases of quantum many-particle systems. Topological order characterizes multi-particle quantum entanglement in the ground state,and leads to gauge fields (abelian or non-abelian)
in the description of the excitations. Indeed, there is emerging understanding that even the gauge fields of elementary particle physics do not reflect some fundamental “symmetry”,but are convenient tools to describe the quantum entanglement of the vacuum.I will give examples of topological order in models of the high temperature superconductors,and connect them to recent observations and numerical computations on the“pseudogap” phase.