Optical Traps for Sympathetic Cooling of Ions with Ultracold Neutral Atoms

Area of Science:

• Atomic Physics
• Quantum Optics
• Ultracold Matter

Background:

• Trapping neutral atoms and ions separately is common, but combining them in a single potential without radio frequency (rf) fields presents challenges.
• Existing methods using rf traps are limited by rf-driven, micromotion-induced heating, hindering precise control and cooling of ions.
• Sympathetic cooling, where one species cools another, is crucial for achieving ultracold temperatures in mixed atomic-ionic systems.

Purpose of the Study:

• To demonstrate the simultaneous trapping of ultracold neutral Rubidium (Rb) atoms and Barium ions (Ba+) in a shared optical potential.
• To achieve efficient sympathetic cooling of Ba+ ions using ultracold Rb atoms.
• To overcome the limitations of traditional radio frequency (rf) traps for ultracold ion-atom mixtures.

Main Methods:

• Utilized a common optical potential to trap ultracold neutral Rb atoms and Ba+ ions.
• Prepared Ba+ ions at an initial temperature of 370 μK.
• Demonstrated sympathetic cooling of Ba+ ions by 100 μK after a single collision with Rb atoms.

Main Results:

• Successfully trapped ultracold Rb atoms and Ba+ ions in the same optical potential.
• Achieved efficient sympathetic cooling of Ba+ ions, reducing their temperature by 100 μK.
• Identified that current limitations are due to Rb density and three-body losses.

Conclusions:

• The developed method successfully traps and cools ion-atom mixtures without rf fields, overcoming heating limitations.
• This technique is versatile and applicable to a broad range of ion-atom species.
• The approach opens possibilities for novel ultracold chemistry experiments and the study of complex many-body dynamics.