High sensitivity magnetometry with Cs vapor

Spin-exchange relaxation free(SERF) magnetometry based on potassium has breakdown the magnetic field sensitivity record previously kept by the superconducting quantum interference devices (SQUIDs). We describe a Cs atomic magnetometer also operating in SERF regime. Utilizing a 20$\times$20$\times$20 mm vapor cell with a relative low temperature of 106 $^{\circ}$C, we achieve the resonance linewidths 2.703Hz corresponding to an electron spin-exchange rate of 357 s$^{-1}$, and demonstrate magnetic field sensitivity of 8 fT/Hz1/2 in a single channel, as shown in fig. 1. Theoretical analysis shows that fundamental sensitivity limits of this device with a 1 cm$^3$ volume could approach 0.2 fT/Hz1/2. Taking advantage of the higher saturated vapor pressure, Cs magnetometry is particularly appropriate for lower temperatures applications.