One-way quantum interactions for fun and profit

The most common kinds of interactions in physics obey reciprocity: when two systems or particles interact, each one influences the other, and information flows in both directions.  In this talk, I’ll discuss general methods for engineering interactions that break this symmetry, in a fully consistent quantum setting.  These engineered “one-way” quantum interactions open up a host of unusual possibilities, from new methods for manipulating and processing quantum information, to new kinds of topological and many-body physics.  I’ll introduce some of the basic theoretical ideas that underlie these unusual interactions, and connections to recent interest in “non-Hermitian” quantum systems.  I’ll also discuss connections to the "bosonic Kitaev chain", a model that is the bosonic analogue of Kitaev’s celebrated model of a 1D fermionic p-wave superconductor, and that has non-reciprocal properties.  This model exhibits a surprising entanglement phase transition, and has recently been realized in two different experimental platforms.