Highly Spin-Polarized Molecules via Collisional Microwave Pumping

Area of Science:

• Molecular Physics
• Quantum Chemistry
• Laser Cooling and Trapping

Background:

• Producing cold, spin-polarized molecules is crucial for various quantum science applications.
• Existing methods face limitations in efficiency and selectivity for certain molecular states.

Purpose of the Study:

• To develop a general technique for producing cold spin-polarized molecules in Σ electronic states.
• To maximize steady-state spin polarization through controlled collisional relaxation.

Main Methods:

• Utilizing coherent microwave excitation to populate rotationally excited molecular levels.
• Employing collisional quenching to induce spin-flipping and populate a single final spin state.
• Theoretically demonstrating the technique for ^{13}C^{16}O molecules in a cold helium buffer gas.

Main Results:

• Achieving high nuclear spin polarization (≥95%) at 1 K for ^{13}C^{16}O.
• Maximizing polarization by suppressing collisional transitions in the ground rotational manifold (N=0) relative to the excited manifold (N=1).
• Demonstrating high selectivity of the spin-polarization technique.

Conclusions:

• The proposed technique offers a general and highly selective method for preparing cold spin-polarized molecules.
• This method is particularly effective for Σ-state molecules at low temperatures.
• The findings pave the way for advanced applications in quantum information and precision measurements.