Physical Society Colloquium

Holographic Descriptions of Quantum Liquids

John McGreevy

MIT

It turns out that string theory is useful: via the AdS/CFT correspondence, it provides a tractable description of ordinary quantum many-body systems in terms of a gravitational theory in extra dimensions. This exotic description is most effective in regimes of strong interaction, where standard theoretical techniques flounder. I will describe attempts to apply these ideas to real physical systems which have the common feature that strong interactions are important for determining their collective behavior. These ‘quantum liquids’ include the quark-gluon plasma, cold atoms at unitarity, and the normal phase of high-temperature superconductors. I'll conclude with some speculations about a possible new notion of universality.