Trapping and Ground-State Cooling of a Single H_{2}^{+}

Area of Science:

• Atomic, Molecular, and Optical (AMO) Physics
• Quantum Information Science
• Experimental Physics

Background:

• Precise control of molecular ions is crucial for quantum technologies.
• Long chemical lifetimes of molecular ions are essential for advanced spectroscopic techniques.
• Cryogenic environments are key to achieving high-fidelity quantum experiments.

Purpose of the Study:

• To demonstrate co-trapping and sideband cooling of a molecular hydrogen ion (H_{2}^{+}) and a beryllium ion ({}^{9}Be^{+}) pair.
• To investigate the chemical lifetime of H_{2}^{+} at cryogenic temperatures.
• To establish a foundation for quantum logic spectroscopy of H_{2}^{+} and similar light molecular ions.

Main Methods:

• Utilized a cryogenic Paul trap for ion confinement and cooling.
• Employed sideband cooling techniques to reduce translational motion.
• Monitored the chemical lifetime of H_{2}^{+} as a function of apparatus temperature.

Main Results:

• Achieved chemical lifetimes of H_{2}^{+} up to 11_{-3}^{+6} hours at 10 K.
• Cooled two translational modes to average phonon numbers of 0.07(1) and 0.05(1).
• Reached temperatures of 22(1) μK and 55(3) μK for the cooled modes.

Conclusions:

• The demonstrated co-trapping and cooling techniques provide a robust platform for H_{2}^{+} quantum logic spectroscopy.
• This work paves the way for precision measurements on other light molecular ions like HD^{+}, H_{3}^{+}, and He^{+}.
• The long chemical stability achieved is a significant step towards complex molecular ion quantum applications.