Multi-ion Frequency Reference Using Dynamical Decoupling.

Area of Science:

• Atomic, Molecular, and Optical Physics
• Quantum Information Science

Background:

• Trapped atomic ions are promising for high-precision frequency standards.
• Magnetic field fluctuations and other noise sources limit the performance of ion clocks.
• Dynamical decoupling is a technique to mitigate decoherence.

Purpose of the Study:

• To experimentally realize a continuous dynamical decoupling scheme for ion clocks.
• To suppress leading frequency shifts in a multi-ion frequency reference.
• To engineer transitions with reduced sensitivity to environmental noise.

Main Methods:

• Utilized a continuous dynamical decoupling scheme with radio-frequency dressing fields.
• Employed near-resonant magnetic coupling of Zeeman sublevels in ^{40}Ca^{+} ions.
• Applied a second, detuned dressing field to minimize amplitude noise and tensor shifts.

Main Results:

• Achieved suppression of the quadratic dependence of the quadrupole shift to 3(2) mHz/μm².
• Demonstrated coherence times of 290(20) ms on the optical transition.
• Maintained performance in a laboratory environment with significant magnetic field noise.

Conclusions:

• The demonstrated dynamical decoupling effectively suppresses frequency shifts in multi-ion clocks.
• This technique can remove inhomogeneous line shifts in ion-based frequency standards.
• The method shows potential for applications in quantum computing and simulation with trapped ions.