Luminorefrigeration: vibrational cooling of NaCs

Area of Science:

• Molecular Physics
• Laser Cooling
• Quantum Chemistry

Background:

• Ultracold molecules are crucial for fundamental physics and quantum technologies.
• Cooling molecules to their vibrational ground state is essential for precise control and applications.

Purpose of the Study:

• To demonstrate an inexpensive optical pumping technique for cooling ultracold sodium-cesium (NaCs) molecules.
• To prepare molecules in the vibrational ground state X(1)Σ(+)(v=0) from higher vibrational levels (v ≥ 4).

Main Methods:

• Utilized optical pumping with commercially available multimode diode lasers.
• Targeted population transfer into the X(1)Σ(+)(v=0) state of NaCs molecules.
• Investigated the effect of cooling on rotational state distributions.

Main Results:

• Successfully cooled NaCs molecules from v ≥ 4 to the vibrational ground state v=0.
• Observed minimal perturbation of the rotational states, with J(initial)=0-2 evolving to J(final)=0-4.
• Demonstrated an inexpensive and effective method for creating vibrationally cold molecules.

Conclusions:

• Optical pumping provides an accessible route to vibrationally ground-state ultracold polar molecules.
• The method is efficient and minimally affects the rotational distribution, preserving molecular coherence.
• This technique lowers the barrier for research and applications involving ultracold polar molecules.