Sensing Atomic Motion from the Zero Point to Room Temperature with Ultrafast Atom Interferometry.

Area of Science:

• Quantum physics
• Atomic physics
• Quantum optics

Background:

• Trapped atomic ions are crucial for quantum computing and sensing.
• Precisely measuring ion motion is essential for characterizing quantum states and controlling quantum systems.
• Existing methods have limitations in dynamic range and precision for motional state characterization.

Purpose of the Study:

• To develop and demonstrate a novel atom interferometry technique for sensing ion motion.
• To accurately characterize quantum and thermal motional states of trapped ions across a wide energy range.
• To explore the application of this technique in quantum thermometry and ultrafast gate characterization.

Main Methods:

• Utilizing a sequence of state-dependent ultrafast momentum kicks on a trapped atomic ion.
• Employing atom interferometry to probe the motional state of the ion.
• Measuring the ion's motional state from near zero-point energy to high thermal populations.

Main Results:

• Successfully characterized a nearly pure quantum state with n=1 phonon.
• Accurately measured thermal states spanning from near zero-point energy to n[over ¯]~10⁴.
• Demonstrated the technique's capability to extend to significantly higher energies.
• Showcased the method's applicability beyond the Lamb-Dicke regime.

Conclusions:

• The developed atom interferometer provides a powerful tool for precise motional state characterization of trapped ions.
• This technique offers a broad dynamic range suitable for both quantum ground states and high-temperature thermal states.
• Interferometric methods show promise for advanced quantum thermometry and characterizing ultrafast entangling gates in multi-ion systems.