"Spin orbit coupled atomic gases"

Gauge fields are ubiquitous in Physics. For example, in the context of high energy physics, they are the fundamental carrier of forces; while in condensed matter systems the associated physical fields (electrical and magnetic) are essential in creating and understanding many-body phenomena. These fields can depend on internal — spin — degrees of freedom, and in material systems these spin-dependent gauge fields are often manifest as spin-orbit coupling (SOC, but more correctly spin-crystal momentum coupling).Here I present our experimental work synthesizing SOC for ultracold neutral atoms. I will first show how we use the light-matter interaction to engineer gauge terms in the atomic Hamiltonian, and then how to make these depend on spin. Using such techniques, we created SOC in a pseudo-spin 1/2 Bose gas and observed a previously unexpected quantum phase transition. I will conclude by showing the observed phase diagram of a spin-1 spin-orbit coupled Bose gas: a context without analog in traditional condensed matter systems.