Spin-exchange-relaxation-free magnetometry with Cs vapor

Abstract

We describe a Cs atomic magnetometer operating in the spin-exchange-relaxation-free (SERF) regime. With a vapor cell temperature of $103°\text{C}$ we achieve intrinsic magnetic resonance widths $\Delta B=17\mu \text{G}$ corresponding to an electron spin-relaxation rate of $300{\text{s}}^{-1}$ when the spin-exchange rate is ${\Gamma }_{\text{SE}}=14000{\text{s}}^{-1}$. We also observe an interesting narrowing effect due to diffusion. Signal-to-noise measurements yield a sensitivity of about $400\text{pG}/\sqrt{\text{Hz}}$. Based on photon shot noise, we project a sensitivity of $40\text{pG}/\sqrt{\text{Hz}}$. A theoretical optimization of the magnetometer indicates sensitivities on the order of $2\text{pG}/\sqrt{\text{Hz}}$ should be achievable in a $1{\text{cm}}^3$ volume. Because Cs has a higher saturated vapor pressure than other alkali metals, SERF magnetometers using Cs atoms are particularly attractive in applications requiring lower temperatures.