E. N. Fortson

Improved limit on the permanent electric dipole moment of 199Hg.

We report the results of a new experimental search for a permanent electric dipole moment of 199Hg utilizing a stack of four vapor cells. We find d(199Hg)=(0.49+/-1.29_{stat}+/-0.76_{syst})x10;{-29} e cm, and interpret this as a new upper bound, |d(199Hg)|<3.1x10;{-29} e cm (95% C.L.). This result improves our previous 199Hg limit by a factor of 7, and can be used to set new constraints on CP violation in physics beyond the standard model.

New limit on the permanent electric dipole moment of 199Hg.

We present the first results of a new search for a permanent electric dipole moment of the 199Hg atom using a UV laser. Our measurements give d(199Hg) = -(1.06+/-0.49+/-0.40)x10(-28)e cm. We interpret the result as an upper limit absolute value [d(199Hg)]<2.1x10(-28)e cm (95% C.L.), which sets new constraints on theta bar;(QCD), chromo-EDMs of the quarks, and CP violation in supersymmetric models.

Optical clocks based on ultranarrow three-photon resonances in alkaline earth atoms

A sharp resonance line that appears in three-photon transitions between the 1S0 and 3P0 states of alkaline earth and Yb atoms is proposed as an optical frequency standard. This proposal permits the use of the even isotopes, in which the clock transition is narrower than in proposed clocks using the odd isotopes and the energy interval is not affected by external magnetic fields or the polarization of trapping light. With this method, the width and the rate of the clock transition can, in principle, be continuously adjusted from the MHz level to sub-mHz without loss of signal amplitude by varying the intensities of the three optical beams. Doppler and recoil effects can be eliminated by proper alignment of the three optical beams or by point confinement in a lattice trap. Light-shift effects on the clock accuracy can be limited to below a part in 10(18).

Radio frequency spectroscopy with a trapped Ba+ ion: recent progress and prospects for measuring parity violation

We have employed the method of shelving to measure Zeeman resonances of a single trapped Ba+ ion in low magnetic fields, and have observed radio frequency transitions with linewidths of 5 Hz, limited by magnetic-field noise. We have also observed the shift in the Zeeman frequency when the ion is illuminated by off-resonant light. A simultaneous measurement of such light shifts in two atomic states of Ba+ will permit a precise determination of the ratio of transition matrix elements. Furthermore, using this method with an ion in a standing lightwave, a proposed parity nonconservation (PNC) measurement with Ba+ or Ra+ could be realized. In this paper we review methods and the status of these experiments and discuss the remaining challenges of the PNC experiment.

Precision Measurement of Light Shifts in a Single Trapped Ba^+ Ion

Experimental tests of atomic theory often involve the measurement of atomic state lifetimes, oscillator strengths, polarizabilities [1], and other properties which depend directly on atomic dipole matrix elements. Absolute measurements of these quantities can be difficult. Another approach [2] is to make high precision measurements of properties which can be directly calculated using modern atomic theory techniques and depend on ratios of atomic matrix elements. Here we report a 0.1% measurement of the ratio R of the ac Stark effect (or light shift) in the 6S1/2 and 5D3/2 states of a singly-ionized barium ion, iso-electronic to the well-studied alkali atom Cs. Comparison of this result with an ab initio calculation of R would yield a new test of atomic theory. Since R is expressible as ratios of matrix elements (shown below), this measurement also establishes a sum rule relating the barium matrix elements known to ∼ 1% or better (i.e. h 6S1/2||r||6P1/2,3/2i ) to matrix ele

Measurement of light shifts at two off-resonant wavelengths in a single trapped Ba+ ion and the determination of atomic dipole matrix elements

We define and measure the ratio (R) of the vector ac-Stark effect (or light shift) in the 6S_1/2 and 5D_3/2 states of a single trapped barium ion to 0.2% accuracy at two different off-resonant wavelengths. We earlier found R = -11.494(13) at 514.531nm and now report the value at 1111.68nm, R = +0.4176(8). These observations together yield a value of the matrix element, previously unknown in the literature. Also, comparison of our results with an ab initio calculation of dynamic polarizability would yield a new test of atomic theory and improve the understanding of atomic structure needed to interpret a proposed atomic parity violation experiment.

Nuclear magnetic octupole moment and the hyperfine structure of the 5 D 3 / 2 , 5 / 2 states of the Ba + ion

The hyperfine structure of the long-lived

Measurement of linear stark interference in 199Hg.

5{D}_{3/2}

New search for a permanent electric dipole moment of 199Hg.

and

Studies of the /sup 1/S/sub 0/-/sup 3/P/sub 0/ transition in atomic Yb for optical clocks and qubit arrays

5{D}_{5/2}