Quantum-limited measurements on trapped laser-cooled ions

Wayne M. Itano, James C Bergquist, J. J. Bollinger +5 more

Joseph F. Goodwin, G. Stutter, Richard Claude Thompson +1 more

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.

Kenji Toyoda, Shinji Urabe

B. B. Blinov, R. N. Kohn, M. J. Madsen +3 more

We demonstrate broadband laser cooling of atomic ions in an rf trap using ultrafast pulses from a mode-locked laser. The temperature of a single ion is measured by observing the size of a time-averaged image of the ion in the known harmonic trap potential. Although the lowest observed temperature was only about 1K, this method efficiently cools very hot atoms and can sufficiently localize trapped atoms to produce near diffraction-limited atomic images.

Hidetsuka Imajo, Shinji Urabe, Kazuhiro Hayasaka +1 more

The characteristics of laser-cooled Be+ ions stored in a Penning trap are reported. Be+ ions are cooled by a laser to approximately 300 mK and the cyclotron and axial frequencies of the cooled ions are measured by a laser fluorescence technique. In addition, ion resonances are observed when several kinds of ions are trapped with Be+ ions.

Wayne M. Itano, Jonas Bergquist, J. J. Bollinger +1 more