Search For The Atomic Electric Dipole Moment Of ¹⁷¹Yb

The existence of a permanent electric dipole moment(EDM)violates the timereversal symmetry(T),the parity symmetry(P)and,under the CPT(charge conjugation,parity and time reversal)theorem,the CP symmetry as well.Therefore,EDM searches are sensitive to new CP-violating interactions,a type of new physics beyond the Standard Model.The atomic EDM of 171 Yb is an important case in the nuclear sector.It was proposed more than 20 years ago,but no measurements had previously been carried out.In this dissertation,we completed the first atomic EDM measurement of 171 Yb.We preform the EDM measurements on cold atoms held in an optical dipole trap(ODT)at 1035.8 nm,which is determined in this work to be the magic wavelength for the 6s6p 1S0?6s6p 3P1 inter-combination transition.The use of the magic wavelength eliminates the AC Stark shift and broadening and enables more efficient spinstate detection using the inter-combination transition.By applying a novel quantum non-demolition(QND)method based on the optical dressing effect to the spin-state detection,the detection efficiency is increased by a factor of 50 compared to the commonly used non-QND method.With the improved EDM sensitivity,we observe for the first time the parity-mixing systematic effect,and suppress this systematic effect by averaging between measurements with ODTs in opposite directions.Finally the EDM is determined to be d(171 Yb)=(-0.68±0.51star±0.12syst)×10-26 e·cm,leading to an upper limit of |d(171 Yb)|<1.5×10-26 e·cm(95%C.L.).The EDM precision we have achieved in this first measurement is 1000 times better than the previous measurement on 225Ra using the ODT method.The measurement techniques developed in this work can be adapted to searching for the EDM of 225Ra.