Frequency comparison of two high-accuracy Al+ optical clocks

Area of Science:

• Atomic Physics
• Quantum Metrology
• Spectroscopy

Background:

• Optical atomic clocks are crucial for fundamental physics tests and timekeeping.
• Aluminum ion (Al+) clocks offer potential for high accuracy due to their suitable atomic structure.
• Quantum logic spectroscopy is a leading technique for probing atomic transitions with high precision.

Purpose of the Study:

• To construct and characterize a novel optical clock based on the Al+ ion.
• To achieve a fractional frequency inaccuracy below 1x10^-17.
• To compare the performance of the new clock with a previously developed Al+ optical clock.

Main Methods:

• Employed quantum logic spectroscopy on a single Al+ ion.
• Utilized a simultaneously trapped Mg+ ion for sympathetic cooling and state detection of the Al+ ion.
• Compared the frequency of the {1}S{0}<-->{3}P{0} transition with a prior Al+ optical clock.

Main Results:

• Achieved a fractional frequency inaccuracy of 8.6x10^-18 for the new Al+ optical clock.
• Observed a relative stability of 2.8x10^-15 tau^-1/2 between the two Al+ clocks.
• Measured a fractional frequency difference of -1.8x10^-17, consistent with the older clock's accuracy limit.

Conclusions:

• The newly constructed Al+ optical clock demonstrates state-of-the-art accuracy.
• Sympathetic cooling with Mg+ ions is an effective method for high-precision spectroscopy.
• This work advances the development of next-generation atomic clocks for metrology and fundamental science.