Comparison of discharge lamp and laser pumped cesium magnetometers

Abstract

We have performed a comparison of laser (LsOPM) and lamp (LpOPM) pumped cesium vapor magnetometers. Although the LsOPM operated 50% above its shot-noise limit we found an intrinsic sensitivity of 15 fT/\sqrt{Hz} and 25 fT/\sqrt{Hz} for the LsOPM and LpOPM respectively. Two modes of operation, viz.,the phase-stabilized and the self-oscillating mode were investigated and found to yield a similar performance. We have compared the performance of the LsOPM and the LpOPM directly by simultaneous measurements of field fluctuations of a 2 microtesla magnetic field inside a multilayer magnetic shield and have used one of the magnetometers for an active field stabilization. In the stabilized mode we found a gradient instability of 25 fT within an integration time of 100 s, which represents an upper limit of the long-term stability of the magnetometers.Comment: 11 pages, 13 figures, 1 tabl

Synchronous optical pumping of quantum revival beats for atomic magnetometry

“…We find that it creates a coherently oscillating superposition state with a spin polarization a factor of 4 higher than can be obtained without double modulation for the same average laser power. We also model the effects in other alkali atoms and find that the amount of polarization enhancement increases for systems with a larger number of quantum states.Because the revivals occur in geomagnetic field range of about 0.5 G, our experiments are also directly applicable to optically-pumped alkali-metal magnetometers, which are used in many applications, from archaeology [18] and mineral exploration [19] to searches for a CPviolating electric dipole moment [20]. As was recently discussed in [21,22], Breit-Rabi mixing of Zeeman levels decreases magnetometer sensitivity by splitting the Zeeman resonance into many separate lines.…”

Optical magnetometry

“…Another technique for reducing wall relax-ation is application of a non-relaxing coating, typically, paraffin, on the cell walls (see below). As mentioned above, the light sources of choice today are diode lasers; however, discharge lamps -the original light sources for atomic magnetometers -are still used in most commercial atomic magnetometers, and can achieve sensitivity comparable to lasers in some research applications [14]. Figure 1 shows separate light sources for pumping and probing with orthogonal light beams.…”

Low-noise high-density alkali-metal scalar magnetometer

“…High-density hot alkali-metal vapors are used in such vital metrology applications as atomic clocks [1] and magnetometers [2,3,4]. In these applications the resolution of frequency measurements of the hyperfine or Zeeman resonance can be improved by increasing the density of alkali-metal atoms until the resonance begins to broaden due to alkali-metal spin-exchange (SE) collisions.…”

“…Some of these applications require magnetometers that can measure small (∼ fT) changes in geomagnetic-size fields with a fractional sensitivity of 10 −10 − 10 −11 . Existing sensitive scalar magnetometers use large cells filled only with alkali-metal vapor and rely on a surface coating to reduce relaxation of atoms on the walls [2,3,4]. Here we use helium buffer gas to reduce diffusion of alkali atoms to the walls, which also allows independent measurements of the magnetic field at several locations in the same cell [11].…”