Probing the short range spin dependent interactions by polarized 3^{3} 3 He atom beams

Experiments using polarized 3He atom beams to search for short range spin dependent forces are proposed. High intensity, high polarization, small beam size 3He atom beams have been successfully produced and used in surface science researches. By incorporating background reduction designs as combination shielding by µ-metal and superconductor and double beam paths, the precision of spin rotation angle per unit length could be improved by a factor of ~104. By this precision, in combination with a high density and low magnetic susceptibility sample source mass, and reversing one beam path if necessary, sensitivities on three different types of spin dependent interactions could be improved by as much as ~102 to ~108 over the current experiments at the millimeter range

Optical Magnetometry

Some of the most sensitive methods of measuring magnetic fields utilize interactions of resonant light with atomic vapor. Recent developments in this vibrant field are improving magnetometers in many traditional areas such as measurement of geomagnetic anomalies and magnetic fields in space, and are opening the door to new ones, including, dynamical measurements of bio-magnetic fields, detection of nuclear magnetic resonance (NMR), magnetic-resonance imaging (MRI), inertial-rotation sensing, magnetic microscopy with cold atoms, and tests of fundamental symmetries of Nature.Comment: 11 pages; 4 figures; submitted to Nature Physic

Femtotesla Nearly-Quantum-Noise-Limited Pulsed Gradiometer at Earth-Scale Fields

We describe a magnetic gradiometer that operates at finite fields and uses an intense pulsed laser to polarize a 87Rb atomic ensemble and a compact vertical-cavity surface-emitting laser probe laser to detect paramagnetic Faraday rotation in a single multipass cell. We report differential magnetic sensitivity of 14 fT/Hz1/2, corresponding to gradiometer sensitivity of 70 fT/cm/√Hz with a 0.2 cm baseline, over a broad dynamic range, including Earth’s field magnitude and a common-mode rejection ratio higher than 104. We also observe a nearly quantum-noise-limited behavior of the gradiometer by comparing the experimental standard deviation of the estimated frequency difference against the Cramér-Rao lower bound in the presence of white photon shot-noise, atomic spin noise, and diffusion