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Optical Frequency Standards

Active and Passive Frequency Standards

Optical frequency standards are crucial for precise frequency measurements. Active standards involve lasers emitting well-defined optical frequencies, while passive standards have a known frequency response used in building active standards.

Standards Based on Optical Transitions

Optical frequency standards are typically based on precise optical transitions of atoms, ions, or molecules. These transitions are used to stabilize the frequency of single-frequency lasers, ensuring high precision in measurements.

Requirements for High-Precision Standards

For optimal performance in optical atomic clocks, atoms, ions, or molecules used should have narrow linewidths, convenient clock frequencies, suitable transitions for laser cooling, and be insensitive to external factors like electric or magnetic fields.

Reference Cavities for Stability

Reference cavities are utilized as flywheel oscillators to stabilize lasers in optical frequency standards. They provide short-term stability, while the optical transitions maintain long-term stability.

Accuracy, Precision, Stability

In frequency metrology, accuracy refers to the closeness of measured frequency to the true value, precision is the consistency of repeated measurements, and stability indicates the frequency’s resistance to drift over time.

Advancements in Frequency Standards

Research continues to improve optical frequency standards, aiming for higher accuracies and stabilities. New technologies such as optical lattice clocks and single-ion frequency standards push the boundaries of precision in frequency metrology.

Source: Nature
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