Test of Cosmic Spatial Isotropy for Polarized Electrons Using a Rotatable Torsion Balance

Abstract

To test the cosmic spatial isotropy, we use a rotatable torsion balance carrying a transversely spin-polarized ferrimagnetic ${\mathrm{D}\mathrm{y}}_{6}{\mathrm{F}\mathrm{e}}_{23}$ mass. With a rotation period of 1 h, the period of anisotropy signal is reduced from one sidereal day by about 24 times, and hence the $1/f$ noise is reduced. Our present experimental results constrain the cosmic anisotropy Hamiltonian $H={C}_{1}{\ensuremath{\sigma}}_{1}+{C}_{2}{\ensuremath{\sigma}}_{2}+{C}_{3}{\ensuremath{\sigma}}_{3}$ (${\ensuremath{\sigma}}_{3}$ is in the axis of earth rotation) to $({C}_{1}^{2}+{C}_{2}^{2}{)}^{1/2}=(1.1\ifmmode\pm\else\textpm\fi{}2.0)\ifmmode\times\else\texttimes\fi{}{10}^{\ensuremath{-}20}\text{ }\mathrm{e}\mathrm{V}$ and $|{C}_{3}|=(1.1\ifmmode\pm\else\textpm\fi{}6.0)\ifmmode\times\else\texttimes\fi{}{10}^{\ensuremath{-}19}\text{ }\mathrm{e}\mathrm{V}$. This improves the previous limits on $({C}_{1}^{2}+{C}_{2}^{2}{)}^{1/2}$ by 27 times.