Formation of quantum-degenerate sodium molecules

Area of Science:

• Atomic, Molecular, and Optical (AMO) Physics
• Quantum Chemistry
• Condensed Matter Physics

Background:

• Bose-Einstein condensates (BECs) are quantum states of matter formed by cooling atoms to near absolute zero.
• Ultracold molecules offer unique opportunities for studying quantum phenomena and chemical reactions.
• Feshbach resonances provide a powerful tool for controlling atomic interactions and forming molecules.

Purpose of the Study:

• To produce ultracold sodium molecules from a Bose-Einstein condensate.
• To achieve efficient conversion and high purity of the molecular sample.
• To investigate the properties of the resulting ultracold molecules.

Main Methods:

• Formation of an atomic Bose-Einstein condensate of sodium atoms.
• Ramping an applied magnetic field across a Feshbach resonance to induce molecule formation.
• Selective removal of remaining atoms using resonant laser light.
• Time-of-flight analysis to characterize the molecular sample.

Main Results:

• Production of over 10^5 ultracold sodium molecules.
• Achieved a conversion efficiency of approximately 4% from atoms to molecules.
• Selective atom removal prevented rapid collisional relaxation of the molecules.
• Obtained an instantaneous phase-space density greater than 20 for the pure molecular sample.

Conclusions:

• Ultracold sodium molecules can be efficiently produced from a BEC using magnetic Feshbach resonances.
• Selective laser-based atom removal is effective in preserving the ultracold molecules.
• The high phase-space density achieved indicates a highly quantum degenerate molecular sample.