"Vapor cell atomic magnetometers and co-magnetometers"
I will report our recent progress on vapor cell atomic magnetometers and co-magnetometers. The first part of the talk describes a Rb scalar gradiometer using two multipass optical cells. We use a pump-probe measurement scheme to suppress spin-exchange relaxation and reach sub-femtotesla magnetic field sensitivity. It approaches, for the first time, the fundamental limit set by Rb-Rb collisions. The second part of the talk describes a system of He, Xe and alkali metal atoms, where the alkali metal atoms both hyperpolarize and detect the noble gas nuclear spin. We apply a scheme to largely suppress the systematic effects of the electron spin polarization on the nuclear spin Larmor frequency. We study the response of He and Xe Larmor frequency ratio in presence of temperature and magnetic field gradient, which violates the basic assumption of co-magnetometers that both species measure the same field at the same time.