Sisyphus cooling of electrically trapped polyatomic molecules.

Area of Science:

• Atomic, Molecular, and Optical Physics
• Quantum Information Science
• Ultracold Chemistry

Background:

• Polar molecules possess rich internal structures and long-range interactions, crucial for quantum applications.
• Their full potential is realized at ultracold temperatures, enabling diverse phenomena in many-body physics and beyond the standard model.
• Cooling polyatomic molecules to ultracold temperatures has been a significant experimental challenge.

Purpose of the Study:

• To experimentally demonstrate optoelectrical cooling, a novel method for cooling and accumulating polar molecules.
• To overcome the intractability of cooling polyatomic molecules to ultracold temperatures.

Main Methods:

• Optoelectrical cooling utilizes a Sisyphus effect to remove a large fraction of kinetic energy per cycle.
• The method involves a few repetitions of a dissipative decay process for efficient cooling.
• The scheme operates within a trap, providing three-dimensional cooling.

Main Results:

• Reduced the temperature of approximately one million CH(3)F molecules by a factor of 13.5.
• Increased the phase-space density by a factor of 29 (or 70, excluding trap losses).
• Demonstrated cooling in all three dimensions within a trap.

Conclusions:

• Optoelectrical cooling is a viable method for producing ultracold polyatomic molecules.
• The technique is expected to work for a wide range of polar molecules, with no fundamental temperature limit below the nanokelvin range.
• Achieved low temperatures, large molecule numbers, and long trapping times (up to 27 seconds), enabling interaction-dominated regimes for collision studies and evaporative cooling towards Bose-Einstein condensates.