Towards a transportable aluminium ion quantum logic optical clock

Area of Science:

• Atomic Physics
• Quantum Optics
• Metrology

Background:

• Optical clocks achieve unprecedented fractional frequency uncertainties (<10^-17).
• New applications like chronometric leveling require high-precision timekeeping.
• Transportable optical clocks are crucial for deploying these advancements outside laboratory settings.

Purpose of the Study:

• To develop a compact and transportable optical clock based on a single trapped aluminum ion (²⁷Al⁺).
• To utilize quantum logic spectroscopy with singly charged calcium ions (⁴⁰Ca⁺) for sympathetic cooling, state preparation, and readout.
• To present a simplified physics and laser package for ion manipulation.

Main Methods:

• Development of a segmented multilayer ion trap with distinct loading and probing zones.
• Integration of a compact titanium vacuum chamber and a high numerical aperture imaging system.
• Implementation of an all-fiber laser system for ⁴⁰Ca⁺ repumping and quantum logic operations.

Main Results:

• Preliminary estimates of trap-induced frequency shifts on ²⁷Al⁺ were obtained using ⁴⁰Ca⁺.
• The micromotion-induced second-order Doppler shift for ²⁷Al⁺ was measured as -0.4_-0.3^+0.4×10^-18.
• The black-body radiation shift for ²⁷Al⁺ was determined to be (-4.0 ± 0.4) × 10^-18.
• Measured heating rates of 30(7) quanta/sec enabled interrogation times of hundreds of milliseconds.

Conclusions:

• The developed compact physics package is suitable for building transportable optical clocks.
• The quantum logic spectroscopy approach with ⁴⁰Ca⁺ is effective for interrogating ²⁷Al⁺.
• The preliminary frequency shift measurements are critical for understanding clock performance and accuracy.