Sideband cooling of atomic and molecular ions

Single trapped ions are a near ideal quantum system that can be spectroscopically probed with incredibly high precision. Although molecular ions typically lack strong cycling transitions for efficient cooling and detection, a single atomic ion can be used to sympathetically cool a single molecular ion to the quantum mechanical ground state of motion. By using the quantum logic spectroscopy scheme, transitions can be probed on the molecular ion and detected using the atomic ion. For such experiments, we use 40Ca+ as the cooling/detection ion and MgH+ as the spectroscopy ion.

Chemical reactions with Doppler cooled ions

In recent years, much progress has been made in extending laser cooling techniques to both neutral molecules1,2 and molecular ions3,4. One particularly promising class of molecular ions for cooling and precision spectroscopy are alkaline earth monohalide ions5. To produce translationally cold BaF+ and BaCl+ ions, we react Ba+ ions at mK temperatures with neutral gases at room temperature. To this end, we have performed experiments measuring reaction rates and characterizing reaction products between neutral molecules, such as SF6 and CH3Cl, and Ba+.

Nuclear isomer transition in 229Th3+

To excite most nuclei above the ground isomeric state, energies of order keV to MeV are required. The 229Th isotope, on the other hand, is believed to possess an energy splitting of only 7.6(5) eV, putting it in reach of tabletop UV lasers6. Along with the exceptional isolation of the nucleus from the outside environment, the narrow linewidth of this transition could be exploited for a new generation of high precision clocks7. Further applications of this nuclear transition could include enhanced sensitivity to variations in the fine structure constant8.

Recently, our collaborators in the Kuzmich lab succeeded in directly laser cooling 229Th3+9.



  1. "Production of translationally cold barium monohalide ions," M. V. DePalatis and M. S. Chapman, Phys. Rev. A 88, 023403 (2013). (Link)
  2. "Charge exchange and chemical reactions with trapped Th3+," L. R. Churchill, M. V. DePalatis, and M. S. Chapman, Phys. Rev. A 83, 012710 (2011). (Link)
  3. "Multiply Charged Thorium Crystals for Nuclear Laser Spectroscopy," C. J. Campbell, A. V. Steele, L. R. Churchill, M. V. DePalatis, D. E. Naylor, D. N. Matsukevich, A. Kuzmich, and M. S. Chapman, Phys. Rev. Lett. 102, 233004 (2009). (Link)


  1. "Optical frequency comb Raman spectroscopy of trapped calcium ions," M. V. DePalatis, Gregers Poulsen, and Michael Drewsen, 557th WE Heraues-Seminar, Bad Honnef, Germany, March 2014.
  2. "Lifetime Measurements of Trapped 232Th3+," M. V. DePalatis and M. S. Chapman, DAMOP 2012] County, CA, June 2012. (DAMOP abstract)
  3. "Charge exchange and chemical reactions with trapped thorium ions," M. V. DePalatis, L. R. Churchill, and M. S. Chapman, DAMOP 2011, Atlanta, GA, June 2011. (DAMOP abstract)
  4. "Multiply charged thorium ions for nuclear laser spectroscopy," M. V. DePalatis, C. J. Campbell, L. R. Churchill, D. E. Naylor, A. Radnaev, M. S. Chapman, and A. Kuzmich, DAMOP 2010, Houston, TX, May 2010. (DAMOP abstract)
  5. "Multiply charged ionic crystals for nuclear laser spectroscopy," C. J. Campbell, A. V. Steele, L. R. Churchill, M. V. DePalatis, D.E. Naylor, D. N. Matsukevich, M. S. Chapman, and A. Kuzmich, DAMOP 2009 Charlottesville, VA, May 2009. (DAMOP abstract)


  1. E.S. Shuman et al., Nature 467, 820 (2010). 

  2. M. Hummon et al., Phys. Rev. Lett. 110, 143001 (2013). 

  3. U. Bressel et al., Phys. Rev. Lett. 108, 183003 (2012). 

  4. J.H.V. Nguyen et al., New J. Phys. 13, 063023 (2011). 

  5. E.R. Hudson, Phys. Rev. A 79, 032716 (2009). 

  6. B.R. Beck et al., Phys. Rev. Lett. 98, 142501 (2007). 

  7. E. Peik and C. Tamm, Europhys. Lett. 61, 181 (2003). 

  8. V.V. Flambaum, Phys. Rev. Lett. 97, 092502 (2006). 

  9. C.J. Campbell, A.G. Radnaev, and A. Kuzmich, Phys. Rev. Lett. 106, 223001 (2011).