Center for Theoretical Physics (Pupin Hall 8th Floor)
"Quantum Matter Out of Equilibrium"
A central goal of condensed matter physics is to study the universal emergent properties of macroscopic quantum systems with large numbers of interacting particles. Due to a variety of conceptual and experimentally motivated reasons, the traditional approach of many-body physics is largely built around the study of low-temperature and near-equilibrium properties of time independent Hamiltonians. A confluence of developments across a range of subfields --- particularly experimental advances in building programmable quantum devices --- have opened up a vast new territory of studying many-body phenomena in completely novel regimes: highly excited, "post Hamiltonian", and far from equilibrium. The natural evolutions implemented by these novel experiments are out-of-equilibrium dynamics generated by quantum circuits of unitary gates, possibly interrupted by measurements, and starting from initial states that are not low energy in any useful sense. I will describe some highlights of an active research program to advance many-body theory beyond the regime of near-equilibrium time-independent Hamiltonians, with a view towards uncovering novel emergent phenomena in the non-equilibrium dynamics of many-body systems, and the physics of quantum circuits. For example, certain phases of matter that are forbidden in equilibrium, such as quantum time crystals, have found new life in the out-of-equilibrium setting. Likewise, ``monitored" circuits that include unitary evoluion and measurements can give rise to novel entanglement and teleporatation phases.