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W Nagourney

Publications and source records attributed to W Nagourney.

12 recordsLinked to original sources
PubMed2002

rf Spectroscopy with a single Ba+ ion.

We have employed the method of shelving to measure Zeeman resonances of a single trapped Ba+ ion. We use optical pumping to place the ion in a selected magnetic sublevel of either the 6S(1/2) ground state or the 5D(3/2) metastable state. The ion is exposed to an rf field, and a probing/shelving mechanism detects whether spin-flip transitions have taken place. We have observed rf transitions with linewidths of 15 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.

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PubMed1996

Excitation transfer spectroscopy with two metastable 138Ba+ ions in same trap.

In the absence of lasers approaching trapped ion clock transitions in sharpness we propose to replace the 12.49 m laser field exciting the D3/2-D5/2 transition of the single Ba+ ion A in D3/2 with the near-field of a close by identical ion B in the excited D5/2 state. We tune the frequency of the near-field by the differential Stark shift generated when the center of mass of the tuned ions is slightly moved out of the trap center by a small bias voltage. We demonstrate that the resultant resonant energy exchange can be made considerably faster than the natural lifetime of either metastable level and show how it might be detected.

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PubMed1992

The 31S0-33P0 transition in the aluminum isotope ion 26A1+: a potentially superior passive laser frequency standard and spectrum analyzer.

The aluminum 26 isotope ion is proposed here as a possible candidate for a superior atomic clock. For this even isotope, the extraordinarily long lifetime of the 33P0 state offers a potential clock transition (31S0-33P0) linewidth of 300 microHz. The mF = 0 --> 0 transition has only a quadratic Zeeman shift approximately 4 x 10(-18) at 0.1 Gauss magnetic field, compared to approximately 10(-8) for the hydrogen maser. Electronic quadrupole moments vanish for both J and J' states and with them shifts due to electric field gradients. All shifts have been estimated and are orders of magnitude less than for Hg+ and Ba+, which are being studied as atomic clock elements.

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PubMed1989

The 6S(0)-6P(0) transition in thallium isotope ion Tl: A superior atomic clock.

Experimental and theoretical studies of the forbidden J = 0 --> J' = 0 optical transition 6(1)S(0)-6(3)P(0) in the odd Hg isotopes are in the literature. From this work natural width and quadratic Zeeman effect have been estimated for the same line in the isoelectronic, even thallium ion (204)Tl(+), which has a very small nuclear magnetic moment. For the m(F) = 0 --> 0 component a linewidth of <0.01 Hz and a quadratic Zeeman shift <10(-18) at 0.1 Gauss are found, compared to 1 Hz and approximately 10(-8) for the hydrogen maser. Electronic quadrupole moments vanish for both J and J' states and with them shifts due to electric field gradients. All shifts are orders of magnitude smaller than for Hg(+) and Ba(+), which have been studied as atomic clock elements.

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PubMed1989

Trapped individual ion at absolute zero temperature.

Laser cooling and ion trapping have progressed to such an extent that one can now speak of realizing a confined atom at absolute zero temperature. In this short publication, we analyze an experiment toward such realization using a single Ba(+) ion in a miniature rf trap. The Ba(+) ion is first laser-cooled to the limit where the ion spends most of its time in the zero-point energy state. Then a test sequence allows one to verify whether or not the ion is actually in its zero-point state. The test sequence may also serve as a device for state selection of an atom at absolute zero temperature.

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PubMed1989

Miniature Paul-Straubel ion trap with well-defined deep potential well.

In some recently proposed experiments using ion traps, a Paul trap of conventional size and design is insufficient. We have constructed a miniature Paul-Straubel trap. It has a small elliptic ring ( approximately 0.2 mm) and three pairs of planar electrodes ( approximately 2 cm part) arranged so that they form a cube. The two conventional end-cap electrodes are replaced by the six planar electrodes. The ring is heatable to a high temperature for improving the uniformity of the dc potential on the ring surface. With this trap, we hope to do such fundamental studies as the true zero-point confinement of a single ion.

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PubMed1988

Metastability transfer spectroscopy with two like ions in the same trap.

High-resolution optical spectroscopy of an individual trapped ion is hampered by lack of sharp lasers. This suggests the use of a second metastable excited ion as an ultrasharp light source. To this end, laser-cool two barium ions to an equilibrium distance of approximately 8 mum on the z (symmetry) axis of the trap and, in this (earth)(Ba(+))(2)-molecule, visually or photoelectrically identify them as A and B by their location. Briefly turn on a 455-nm spectral lamp until one of the ions, say the A ion, is pumped into the metastable D(5/2) level and turns invisible. Focus on the visible, spatially well-resolved B ion and turn off the blue and red illumination lasers for approximately 15 s. Then turn them back on again and check on whether the excitation by chance has been transferred to the B ion and is now in the D(5/2) level and dark while the A ion is bright. The cross section for absorption of the lambda(D(5/2) --> S(1/2)) identical with lambda(0) = 1.76 mum radiation by a stationary ion can be >lambda(0) (2)/2pi. Thus, by pushing the two ions together to approximately lambda(0)/4 by turning on a much stronger trapping field during the excitation exchange period, one might be able to detect excitation transfer in >10% of the attempts. The ions are tuned relative to each other by a 0- to 10-mV/cm variable dc field in the z direction, which displaces them axially and causes them to see different rf fields, which Stark-shifts their frequencies. In this way, a resonant transfer response as sharp as twice the natural width of the D(5/2) level, 11 mHz or a Q approximately 0.4 x 10(17), might be demonstrated.

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PubMed1986

Self-excited mono-ion oscillator.

We propose self-excitation as a potentially more sensitive technique for studying a mono-ion oscillator of frequency v(z) approximately 0.1-100 MHz. This technique also makes only low demands on the harmonicity of the ion oscillation. It should therefore work with inexpensive, easily constructed rf traps. In our analysis, the bound ion between the trap electrodes is represented by an effective circuit resembling that of a piezoelectric quartz crystal. The feedback circuit developed, when operated below self-excitation threshold, may also make efficient electronic cooling of the ion possible, particularly in conjunction with a heterodyne feedback scheme. In the super-regenerative mode, the apparatus might function as a powerful atomic amplifier of the ion oscillation for an energy as low as a fraction of hv(z). These techniques may prove especially useful in conjunction with attempts to synthesize in an rf trap a loosely bound anti-hydrogen atom from a positron and antiproton.

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PubMed1983

Linewidth of single laser-cooled Mg ion in radiofrequency trap.

A single Mg(+) has been successfully trapped and cooled in a small radiofrequency trap. The ion was cooled by using the radiation from a single-frequency ring dye laser whose output was doubled in frequency with an NH(4) (2)H(2)PO(4) temperature phasematched crystal; a power of about 22 muW or less was sufficient for all of the experiments. The ion temperature was estimated by a computer fit of the experimental resonance line profile; the resulting linewidth was compared to previously published Mg(+) 3(2)P(3/2) Hanle-effect linewidths. The result is a temperature of 5(-5) (+15) mK, which is lower than that attained previously.

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