Frequency metrology by use of quantum interference.

Area of Science:

• Atomic physics
• Quantum optics
• Nonlinear optics

Background:

• Two-photon excitation is a key process in atomic spectroscopy.
• Phase-sensitive measurements are crucial for high-precision frequency metrology.
• Optical frequency combs and atomic transitions are used for frequency standards.

Purpose of the Study:

• To demonstrate phase-sensitive frequency demodulation using quantum interference in atomic cesium.
• To explore the use of atoms as ultrafast nonlinear mixing elements.
• To propose a new method for absolute frequency comparisons over a wide spectral range.

Main Methods:

• Exploiting quantum interference in the two-photon excitation rate of cesium atoms.
• Utilizing the 6S(1/2) ?6P(3/2) ? 6D(5/2) transition.
• Demonstrating phase-sensitive frequency demodulation over an optical interval of +/- 12.5 THz.

Main Results:

• Successful demonstration of phase-sensitive frequency demodulation.
• Achieved precise control over optical frequencies using atomic interference.
• Validated the concept of using atoms as nonlinear mixing elements.

Conclusions:

• Quantum interference in atomic excitation provides a robust method for frequency demodulation.
• Atoms can serve as efficient ultrafast nonlinear elements for optical signal processing.
• This approach offers a novel pathway for absolute frequency comparisons in the 200-2000 nm range.