Schematic of the
apparatus used to search for a permanent electric dipole moment of mercury
atoms. The atoms are contained in two glass cells located between high
voltage electrodes. We polarize the atoms using a UV laser and measure
the frequency of their precession in a uniform magnetic field B by monitoring
the transmission of the laser beams through the cells. We apply 10kV
to each of the electrodes to create oppositely directed electric fields
E inside the cells. If Hg atoms had a finite electric dipole moment,
the difference between the precession frequencies in the two cells would
depend on the polarity of the high voltage. We measure this difference
with a precision of 0.4 nano-Hz to set the limit on the electric dipole
moment of Hg atoms.
Reported by:
Romalis et al.,
Physical Review Letters, 19 March 2001
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