Sub-Hertz optical frequency comparisons between two trapped 171Yb+ ions

Area of Science:

• Atomic, Molecular, and Optical Physics
• Quantum Metrology
• Spectroscopy

Background:

• Precise frequency comparisons are crucial for advancing atomic clocks and testing fundamental physics.
• Trapped single ions offer a controlled environment for high-precision spectroscopy.

Purpose of the Study:

• To compare the transition frequencies of two single 171Yb+ ions in independent traps.
• To measure key atomic properties, including the quadrupole moment and polarizabilities of the 5d2D(3/2) state.
• To assess the stability and reproducibility of trapped ion frequency standards.

Main Methods:

• High-precision laser spectroscopy of the 6s2S(1/2)-->5d2D(3/2) transition in single 171Yb+ ions.
• Storing ions in independent ion traps to minimize correlated perturbations.
• Applying external electric fields to probe quadratic Stark shifts and determine polarizabilities.

Main Results:

• The quadrupole moment of the 5d2D(3/2) state was measured as 9.32(48) x 10(-40) C m2.
• Scalar and tensor polarizabilities were determined: alphaS(S(1/2)) - alphaS(D(3/2)) = -6.9(1.4) x 10(-40) J m2/V2 and alphaT(D(3/2)) = -13.6(2.2) x 10(-40) J m2/V2.
• A mean frequency difference of 0.26(42) Hz (relative difference of 3.8(6.1) x 10(-16)) was observed between the two ions.

Conclusions:

• The frequency comparison between the two trapped 171Yb+ ions demonstrates high agreement, rivaling state-of-the-art cesium fountain clocks.
• The precise measurements of atomic properties contribute to a better understanding of ytterbium ion spectroscopy.
• This work validates the potential of trapped ytterbium ions as a platform for next-generation atomic clocks and quantum information applications.