Rapid ¹²⁹Xe-Rb spin-exchange rate measurement by using an atomic magnetometer

Area of Science:

• Atomic Physics
• Quantum Optics
• Metrology

Background:

• Accurate determination of spin-exchange rates is crucial for applications in atomic clocks, magnetometry, and fundamental physics research.
• Traditional methods for measuring spin-exchange rates, such as those relying on longitudinal relaxation, can be time-consuming and less suitable for certain experimental conditions.

Purpose of the Study:

• To propose and validate a novel, fast, and accurate method for determining the ¹²⁹Xe-Rb spin-exchange rate.
• To enable efficient measurements using atomic magnetometers operating at low magnetic fields and pressures.

Main Methods:

• Utilized an atomic magnetometer to measure the spin-exchange rate by analyzing the product of maximum transverse spin polarization of ¹²⁹Xe nuclei and the corresponding Rabi frequency.
• Determined the velocity-averaged binary spin-exchange cross section and the rate constant for spin-exchange in ¹²⁹Xe-Rb van der Waals complexes within a ⁴He buffer gas.

Main Results:

• Measured the velocity-averaged binary spin-exchange cross section ⟨σν⟩_SE to be (1.26 ± 0.13) × 10^-16 cm³/s.
• Quantified the rate constant for spin-exchange in ¹²⁹Xe-Rb van der Waals complexes (κ_4He) as 1326 ± 47 s^-1 in ⁴He buffer gas.
• Demonstrated a significant reduction in measurement time, completing the spin-exchange rate determination in minutes.

Conclusions:

• The proposed method offers a substantial improvement in measurement speed and efficiency compared to techniques based on longitudinal relaxation rates.
• This approach is particularly advantageous for vapor cells exhibiting long longitudinal relaxation times, broadening its applicability in precision measurements.