Simultaneous bicolor interrogation in thulium optical clock providing very low systematic frequency shifts

Area of Science:

• Atomic, Molecular, and Optical Physics
• Metrology and Precision Measurement

Background:

• Optical atomic clocks achieve high precision (10^-18 instability/uncertainty) but face challenges with external field sensitivity.
• Demand for simpler, robust atomic clocks with low sensitivity to environmental factors is increasing for transportable and space applications.
• Existing clock designs require complex control of systematic shifts.

Purpose of the Study:

• To implement a synthetic frequency approach for a thulium optical clock.
• To simultaneously interrogate two clock transitions for enhanced stability and reduced systematic errors.
• To minimize sensitivity to external fields and simplify clock operation while maintaining high accuracy.

Main Methods:

• Utilized a synthetic frequency approach for optical clock interrogation.
• Employed simultaneous optical interrogation of two distinct clock transitions in thulium.
• Measured and analyzed the suppression of systematic shifts, including quadratic Zeeman and tensor lattice Stark shifts.

Main Results:

• Achieved suppression of the quadratic Zeeman shift by over three orders of magnitude.
• Reduced the tensor lattice Stark shift effect to below 10^-18 in fractional frequency units.
• Demonstrated minimal sensitivity to cross-talks between the simultaneously interrogated clock transitions.

Conclusions:

• The synthetic frequency approach significantly mitigates systematic shifts in thulium optical clocks.
• This method results in a thulium optical clock that is nearly free from difficult-to-control systematic errors.
• The developed protocol enables simpler operation and high accuracy, suitable for advanced metrology and future space-based clocks.