{"id":59567,"date":"2025-04-29T07:06:06","date_gmt":"2025-04-29T07:06:06","guid":{"rendered":"https:\/\/www.europesays.com\/uk\/59567\/"},"modified":"2025-04-29T07:06:06","modified_gmt":"2025-04-29T07:06:06","slug":"compact-optical-clock-uses-quantum-interference-for-improved-frequency-stability","status":"publish","type":"post","link":"https:\/\/www.europesays.com\/uk\/59567\/","title":{"rendered":"Compact optical clock uses quantum interference for improved frequency stability"},"content":{"rendered":"

\"Scientists<\/p>\n

Theoretically calculated (left) and experimentally observed (right) spectroscopic signals in proposed method. Credit: Peter Yun<\/p>\n

An atomic clock research team from the National Time Service Center of the Chinese Academy of Sciences has proposed and implemented a compact optical clock based on quantum interference enhanced absorption spectroscopy, which is expected to play an important role in micro-positioning, navigation, timing (\u03bcPNT) and other systems.<\/p>\n

Inspired by the successful history of the coherent population trapping (CPT)-based chip-scale microwave atomic clock and the booming of optical microcombs, a chip-scale optical clock was also proposed and demonstrated with better frequency stability and accuracy, which is mainly based on two-photon transition of Rubidium atom ensemble.<\/p>\n

However, the typically required high cell temperatures (~100 \u2103) and laser powers (~10 mW) in such a configuration are not compliant with the advent of a fully miniaturized and low-power<\/a> optical clock.<\/p>\n

To address these limitations, the researchers developed an innovative approach that utilizes enhanced-absorption sub-Doppler resonances on the D1 line of rubidium atoms.<\/p>\n

By employing monochromatic light and carefully tuned polarization settings for counterpropagating pump and probe beams, the researchers observed enhanced absorption due to the constructive or destructive interference<\/a> between two dark states prepared by the pump and probe beams, respectively. The observed absorption-enhanced Doppler-free resonance with a high ratio of signal amplitude to linewidth is favorable for implementing high-performance optical clocks.<\/p>\n

\"Scientists<\/p>\n

Compact optical clocks implemented with enhanced-absorption of sub-Doppler resonances, experimental setup (left) and measured laser frequency stability (right). Credit: Peter Yun<\/p>\n

In addition, the spectroscopic lines are obtained for modest laser powers (around 100 \u00b5W) and cell temperatures (around 40\u2103)\u2014all features of significant interest for demonstrating a compact optical reference.<\/p>\n

The researchers presented a theoretical model that highlights the significant contribution of Zeeman dark states in this spectroscopic scheme. And the theoretically calculated spectroscopic signals agree well with the experimental observations.<\/p>\n

To measure the frequency stability of this optical clock, two identical diode lasers were frequency-stabilized onto enhanced-absorption sub-Doppler resonances. The influence of key parameters on the sub-Doppler resonance features is thoroughly investigated. Using this simple-architecture setup, the researchers demonstrated the locked laser beat-note with a fractional frequency stability of 1.8 x 10\u221212 at 1s and below 10\u221211 at 10,000 s, which is improved by more than two orders of magnitude compared with the free-running case.<\/p>\n

These results demonstrate the potential of this scheme for the implementation of a compact or even chip-scale optical frequency reference, which might find applications in instrumentation, navigation, and metrology.<\/p>\n

This work is a collaboration with Prof. Rodolphe Boudot from the Franche-Comt\u00e9 \u00c9lectronique M\u00e9canique Thermique et Optique\u2014Sciences et Technologies (FEMTO-ST) Institute in France, and the results are published<\/a> in Physical Review Applied.<\/p>\n

More information:<\/strong>
\n\t\t\t\t\t\t\t\t\t\t\t\tPeter Yun et al, Enhanced absorption in Doppler-free spectroscopy of the Rb atom D1 line with monochromatic light: Application to laser-frequency stabilization, Physical Review Applied (2025). DOI: 10.1103\/PhysRevApplied.23.034063<\/a><\/p>\n

\n\t\t\t\t\t\t\t\t\t\t\t\t\tProvided by
\n\t\t\t\t\t\t\t\t\t\t\t\t\t\t\t\t\t\t\t\t\t\t\t\t\t\t\tChinese Academy of Sciences<\/a>
\n\t\t\t\t\t\t\t\t\t\t\t\t\t\t\t\t\t\t\t\t\t\t\t\t\t\t\t\t<\/p>\n

\t\t\t\t\t\t\t\t\t\t\t\t\t\t<\/a>\n\t\t\t\t\t\t\t\t\t\t\t\t\t\t\t\t\t\t\t\t\t\t\t\t\t\t\t\t\t\t\t\t\t\t\t\t\t\t\t<\/p>\n

\n\t\t\t\t\t\t\t\t\t\t\t\tCitation<\/strong>:
\n\t\t\t\t\t\t\t\t\t\t\t\tCompact optical clock uses quantum interference for improved frequency stability (2025, April 28)
\n\t\t\t\t\t\t\t\t\t\t\t\tretrieved 29 April 2025
\n\t\t\t\t\t\t\t\t\t\t\t\tfrom https:\/\/phys.org\/news\/2025-04-compact-optical-clock-quantum-frequency.html\n\t\t\t\t\t\t\t\t\t\t\t <\/p>\n

\n\t\t\t\t\t\t\t\t\t\t\t This document is subject to copyright. Apart from any fair dealing for the purpose of private study or research, no
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