2002/09/09 by J. C. Allred, ROBERT LYMAN, T. W. Kornack +1 · 1 citation
Physics and Astronomy · Medicine · #Atomic and Subatomic Physics Research #Quantum optics and atomic interactions #Advanced MRI Techniques and Applications
paper · doi:10.1103/physrevlett.89.130801
openalex publication_date 2002/09/09 · openalex created_date 2025/10/10 · openalex updated_date 2026/08/04
Alkali-metal magnetometers compete with SQUID detectors as the most sensitive magnetic field sensors. Their sensitivity is limited by relaxation due to spin-exchange collisions. We demonstrate a K magnetometer in which spin-exchange relaxation is completely eliminated by operating at high K density and low magnetic field. Direct measurements of the signal-to-noise ratio give a magnetometer sensitivity of 10 fT Hz^\mathrm\ensuremath-1/2, limited by magnetic noise produced by Johnson currents in the magnetic shields. We extend a previous theoretical analysis of spin exchange in low magnetic fields to arbitrary spin polarizations and estimate the shot-noise limit of the magnetometer to be 2\ifmmode×\else\texttimes\fi10^\ensuremath-18 T Hz^\mathrm\ensuremath-1/2.