High-Sensitivity Atomic Magnetometer Unaffected by Spin-Exchange Relaxation

作者：J. C. Allred, ROBERT LYMAN, T. W. Kornack, Michael Romalis · 发表于：Physical Review Letters · 年份：2002 · DOI：10.1103/physrevlett.89.130801 · 被引用次数：1076 · 研究领域：Atomic and Subatomic Physics Research、Quantum optics and atomic interactions、Advanced MRI Techniques and Applications

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 $10\text{ }\mathrm{f}\mathrm{T}\text{ }\mathrm{H}{\mathrm{z}}^{\mathrm{\ensuremath{-}}\mathrm{1}\mathrm{/}\mathrm{2}}$, 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 $2\ifmmode\times\else\texttimes\fi{}{10}^{\ensuremath{-}18}\text{ }\mathrm{T}\text{ }\mathrm{H}{\mathrm{z}}^{\mathrm{\ensuremath{-}}\mathrm{1}\mathrm{/}\mathrm{2}}$.