AIP conference proceedings

Temperature Measurements of Laser-Cooled Ions in a Penning Trap

M. J. Jensen

Published Jan 1, 2003• 2 citations

Abstract

Between 104 and 106 9Be+ ions are trapped in a Penning trap. The ions are laser‐cooled to ∼millikelvin temperatures, where they form ion crystals. This system is an example of a strongly coupled one‐component plasma. By means of Doppler laser spectroscopy we have measured the temperature and heating rate of the plasma. Initially the heating rate is low, 60 ± 40 mK/s, but after about 100 ms the plasma heats up rapidly to a few kelvin. The onset of the rapid heating coincides with the solid‐liquid phase transition.

DOI: 10.1063/1.1635175

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AIP conference proceedings

Temperature Measurements of Laser-Cooled Ions in a Penning Trap

M. J. Jensen

Published Jan 1, 2003• 2 citations

Publisher

Abstract

DOI: 10.1063/1.1635175

Related papers

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M. J. Jensen, Taro Hasegawa, John Bollinger

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Joseph N. Tan, J. J. Bollinger, A. S. Barton +1 more

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Jan 1, 19940 citations

^{9}\mathrm{Be}^{+}

plasmas were measured for a wide range of experimental parameters. The lowest and highest temperatures were approximately 40 mK and 2 K. The measured and calculated temperatures are in agreement.

We report the laser cooling of a single

^{40}\text{Ca}^+

ion in a Penning trap to the motional ground state in one dimension. Cooling is performed in the strong binding limit on the 729-nm electric quadrupole

S_{1/2}\leftrightarrow D_{5/2}

transition, broadened by a quench laser coupling the

D_{5/2}

and

P_{3/2}

levels. We find the final phonon number to be

\bar{n}=0.014\pm0.009

. We measure the heating rate of the trap to be very low with

\dot{\bar{n}}=2.5\pm 0.3\textrm{s}^{-1}

and a scaled spectral noise density of

\omega S_{E}(\omega)\sim1.6^{-8}\textrm{V}^2\textrm{m}^{-2}\textrm{Hz}^{-1}\textrm{s}^{-1}

, which is consistent with the large ion-electrode distance. We perform Rabi oscillations on the sideband-cooled ion and observe a coherence time of

0.7\pm 0.1\textrm{ms}

, noting that the practical performance is currently limited by the intensity noise of the probe laser.

We report the laser cooling of a single

{^{40}\mathrm{Ca}}^{+}

ion in a Penning trap to the motional ground state in one dimension. Cooling is performed in the strong binding limit on the 729-nm electric quadrupole ${S}_{1/2}\ensuremath{\leftrightarrow}{D}_{5/2}$ transition, broadened by a quench laser coupling the

{D}_{5/2}

and

{P}_{3/2}

levels. We find the final ground-state occupation to be 98(1)%. We measure the heating rate of the trap to be very low with $\stackrel{\ifmmode \dot{}\else \textperiodcentered \fi{}}{\overline{n}}\ensuremath{\approx}0.3(2)\text{ }\text{ }{\mathrm{s}}^{\ensuremath{-}1}$ for trap frequencies from 150--400 kHz, consistent with the large ion-electrode distance.