Deep-ultraviolet quantum interference metrology with ultrashort laser pulses

Area of Science:

• Atomic Physics
• Quantum Metrology
• Laser Spectroscopy

Background:

• Precision spectroscopy at ultraviolet (UV) and shorter wavelengths is limited by the availability of narrow-band lasers.
• Accessing extreme ultraviolet (XUV) and soft X-ray regions for atomic metrology remains a significant challenge.

Purpose of the Study:

• To demonstrate high-accuracy quantum interference metrology on atomic transitions using femtosecond frequency comb lasers.
• To extend the capabilities of frequency comb metrology into the deep-UV, XUV, and soft X-ray spectral regions.
• To improve the accuracy of absolute transition frequencies and isotope shifts in atomic systems.

Main Methods:

• Utilized an amplified train of phase-controlled pulses from a femtosecond frequency comb laser.
• Employed high peak power pulses for efficient harmonic upconversion.
• Performed a proof-of-principle experiment on a deep-UV two-photon transition in krypton (Kr).

Main Results:

• Achieved high-accuracy quantum interference metrology on atomic transitions.
• Demonstrated improved accuracy (over an order of magnitude) for absolute transition frequency and isotope shifts in krypton compared to nanosecond laser pulses.
• Paved the way for extending frequency comb metrology to XUV and soft X-ray spectral regions.

Conclusions:

• Femtosecond frequency comb lasers provide a powerful tool for high-accuracy spectroscopy in challenging spectral regions.
• This technique significantly enhances the precision of measurements for atomic transition frequencies and isotope shifts.
• The method opens new avenues for atomic and ionic metrology in the XUV and soft X-ray domains.