Challenges
Datasets
Workspaces
Papers
Discussions
Leaderboard
Log inSign up
Challenges
Datasets
Workspaces
Papers
Discussions
Leaderboard
Blog
Job Board
Q3AS

© 2026 Aqora Quantum S.A.S.

TermsPrivacyLegal Notice

IEEE Transactions on Instrumentation and Measurement

Raman–Ramsey Interaction for Coherent Population Trapping Cs Clock

Stéphane Guérandel, T. Zanon-Willette, N. Castagna, F. Dahès, Emeric de Clercq, N. Dimarcq, Andr  Clairon

Published Mar 16, 2007• 43 citations
Publisher

Abstract

A gas cell atomic frequency standard based on coherent population trapping (CPT) with Ramsey interrogation pulses is developed. The clock resonance is detected in a Cs cell with buffer gas using two phase-locked diode lasers tuned to the D1 line. A preliminary short-term stability of$3.5 \times 10^{-12}t^{-1/2}$is reported. The CPT specificity allows a new interrogation–detection sequence, i.e., the continuous pulse train, which, with phase modulation, could lead to better short-term stability compared to usual continuous CPT clocks. The parameters optimizing the stability include a high Rabi frequency, a very short measurement time, and an interrogation time equal to the lifetime of the hyperfine coherence.

DOI
10.1109/tim.2007.891124

Related papers

A high-performance Raman-Ramsey Cs vapor cell atomic clock

Moustafa Abdel Hafiz, Grégoire Coget, Peter Yun +3 more

We demonstrate a high-performance coherent-population-trapping (CPT) Cs vapor cell atomic clock using the push-pull optical pumping technique in the pulsed regime, allowing the detection of high-contrast and narrow Ramsey-CPT fringes. The impact of several experimental parameters onto the clock resonance and short-term fractional frequency stability, including the laser power, the cell temperature, and the Ramsey sequence parameters, has been investigated. We observe and explain the existence of a slight dependence on laser power of the central Ramsey-CPT fringe line-width in the pulsed regime. We report also that the central fringe line-width is commonly narrower than the expected Ramsey line-width given by 1/(2TR), with TR the free-evolution time, for short values of TR. The clock demonstrates a short-term fractional frequency stability at the level of 2.3×10−13 τ−1/2 up to 100 s averaging time, mainly limited by the laser amplitude modulation noise. Comparable performances are obtained in the conventional continuous wave regime, with the use of an additional laser power stabilization setup. The pulsed interaction allows to reduce significantly the clock frequency sensitivity to laser power variations, especially for high values of TR. This pulsed CPT clock, ranking among the best microwave vapor cell atomic frequency standards, could find applications in telecommunication, instrumentation, defense or satellite-based navigation systems.

arXiv:1703.04720•Journal of Applied Physics•Mar 10, 2017•86 citations

Investigations on continuous and pulsed interrogation for a CPT atomic clock

N. Castagna, Rodolphe Boudot, Stéphane Guérandel +3 more

We investigated the influence of some critical parameters and operating conditions such as cell temperature, laser intensity, and interrogation technique affecting the performances of a gas cell Cs frequency standard based on coherent population trapping (CPT). Thanks to an original experimental setup, the atoms can be trapped in the dark state and interrogated using continuous wave (CW) or pulsed coherent optical radiations. Using a double-lambda scheme, a signal contrast as high as 52% has been measured in the continuous regime for an optimum cell temperature of 35 degrees C. Compared with the conventional continuous CPT interrogation, the pulsed interrogation technique reduces the light shift by a factor of 300 and allowed it to reach high-frequency stability for higher laser intensities. The frequency stability has been measured to be 9 x 10(-13) for a 1 s integration time. Main noise contributions limiting the short-term and medium-term frequency stability are reviewed and estimated.

IEEE Transactions on Ultrasonics Ferroelectrics and Frequency Control•Feb 1, 2009•60 citations

Limitations of Long-Term Stability in a Coherent Population Trapping Cs Clock

Olga Kozlova, Jean-Marie Danet, Stéphane Guérandel +1 more

Vapor cell atomic clocks exhibit reduced frequency stability for averaging time between about one hundred and a few thousand seconds. Here we report a study on the impact of the main parameters on the mid-to-long term instability of a buffer-gas vapor cell Cs clock, based on coherent population trapping (CPT). The CPT signal is observed on the Cs D1 line transmission, using a double Λ scheme and a Ramsey interrogation technique. The effects on the clock frequency of the magnetic field, the cell temperature, and the laser intensities are reported. We show in particular that the laser intensity shift is temperature dependent. Along with the laser intensity ratio and laser polarization properties, this is one of the most important parameters.

arXiv:1311.1991•IEEE Transactions on Instrumentation and Measurement•Jan 31, 2014•59 citations

Pulsed coherent population trapping spectroscopy in microfabricated Cs–Ne vapor cells

Rodolphe Boudot, Vincent N. Maurice, Christophe Gorecki +1 more

Pulsed coherent population trapping (CPT) spectroscopy is applied in buffer-gas filled Cs–Ne vapor microfabricated cells. The properties of the Ramsey-CPT clock transition central fringe (linewidth, signal amplitude, and contrast) are studied versus several experimental parameters, including the Ramsey sequence and the input laser intensity, and are compared to those obtained in the conventional continuous (CW) interrogation mode. In the pulsed case and for short Ramsey-free evolution times TR, the central fringe linewidth is found to exhibit a small but visible power broadening and is measured to be narrower than the value of 1/(2TR) that is reached for long TR. The microwave hyperfine coherence lifetime T2 in the Cs–Ne microcells is measured to be in the 50–500 μs range. Its dependence to the buffer gas pressure or cell temperature is briefly studied.

Journal of the Optical Society of America B•Apr 4, 2018•11 citations

A CPT-based Cs vapor cell atomic clock with a short-term fractional frequency stability of 3 x 10-13τ-1/2

Moustafa Abdel Hafiz, Xiaochi Liu, Stéphane Guérandel +2 more

This article reports on the development and short-term fractional frequency stability of a continuous-regime (CW) Cs vapor cell atomic clock based on coherent population trapping (CPT). The push-pull optical pumping technique is used to increase the number of atoms that participate to the clock transition, yielding a typical CPT resonance contrast of 25% for a CPT linewidth of about 450 Hz. The clock short-term fractional frequency stability is measured to be 3 x 10 -13 τ -1/2 up to 100 seconds averaging time, in correct agreement with the signal-to-noise ratio limit. The mid-term frequency stability results are currently mainly limited by laser power effects. The detection of high-contrast narrow Raman-Ramsey fringes is demonstrated with this setup by making the atoms interact with a light pulse sequence.

Journal of Physics Conference Series•Jun 1, 2016•6 citations

A CPT-based Cs cell clock using the auto-balanced Ramsey interrogation protocol

Grégoire Coget, Moustafa Abdel Hafiz, Petersen, Michael +5 more

We propose a preliminary theoretical investigation and demonstrate experimentally the application of the autobalanced Ramsey (ABR) interrogation protocol onto a pulsed hot vapor Cs cell microwave atomic clock based on coherent population trapping (CPT). This approach, based on the alternation of two successive Ramsey-CPT sequences with unequal free-evolution times and the subsequent management oftwo interconnected phase and frequency servo loops, is found to allow a reduction of the clock frequency sensitivity to laser power variations. This approach, combined with the implementation of advanced electronics laser power stabilization systems, yields the demonstration of a CPT-based Cs cell clock with a fractional frequency stability at the level of 3.1 × 10−13 τ−1/2 and averaging down to the level of 7 ×10−15 at 2000 s integration time.

•May 21, 2018•0 citations
A gas cell atomic frequency standard based on coherent population trapping (CPT) with Ramsey interrogation pulses is developed. The clock resonance is detected in a Cs cell with buffer gas using two phase-locked diode lasers tuned to the D1 line. A preliminary short-term stability of3.5×10−12t−1/23.5 \times 10^{-12}t^{-1/2}3.5×10−12t−1/2is reported. The CPT specificity allows a new interrogation–detection sequence, i.e., the continuous pulse train, which, with phase modulation, could lead to better short-term stability compared to usual continuous CPT clocks. The parameters optimizing the stability include a high Rabi frequency, a very short measurement time, and an interrogation time equal to the lifetime of the hyperfine coherence.
We demonstrate a high-performance coherent-population-trapping (CPT) Cs vapor cell atomic clock using the push-pull optical pumping technique in the pulsed regime, allowing the detection of high-contrast and narrow Ramsey-CPT fringes. The impact of several experimental parameters onto the clock resonance and short-term fractional frequency stability, including the laser power, the cell temperature, and the Ramsey sequence parameters, has been investigated. We observe and explain the existence of a slight dependence on laser power of the central Ramsey-CPT fringe line-width in the pulsed regime. We report also that the central fringe line-width is commonly narrower than the expected Ramsey line-width given by 1/(2TR), with TR the free-evolution time, for short values of TR. The clock demonstrates a short-term fractional frequency stability at the level of 2.3×10−13 τ−1/2 up to 100 s averaging time, mainly limited by the laser amplitude modulation noise. Comparable performances are obtained in the conventional continuous wave regime, with the use of an additional laser power stabilization setup. The pulsed interaction allows to reduce significantly the clock frequency sensitivity to laser power variations, especially for high values of TR. This pulsed CPT clock, ranking among the best microwave vapor cell atomic frequency standards, could find applications in telecommunication, instrumentation, defense or satellite-based navigation systems.
We investigated the influence of some critical parameters and operating conditions such as cell temperature, laser intensity, and interrogation technique affecting the performances of a gas cell Cs frequency standard based on coherent population trapping (CPT). Thanks to an original experimental setup, the atoms can be trapped in the dark state and interrogated using continuous wave (CW) or pulsed coherent optical radiations. Using a double-lambda scheme, a signal contrast as high as 52% has been measured in the continuous regime for an optimum cell temperature of 35 degrees C. Compared with the conventional continuous CPT interrogation, the pulsed interrogation technique reduces the light shift by a factor of 300 and allowed it to reach high-frequency stability for higher laser intensities. The frequency stability has been measured to be 9 x 10(-13) for a 1 s integration time. Main noise contributions limiting the short-term and medium-term frequency stability are reviewed and estimated.
Vapor cell atomic clocks exhibit reduced frequency stability for averaging time between about one hundred and a few thousand seconds. Here we report a study on the impact of the main parameters on the mid-to-long term instability of a buffer-gas vapor cell Cs clock, based on coherent population trapping (CPT). The CPT signal is observed on the Cs D1 line transmission, using a double Λ scheme and a Ramsey interrogation technique. The effects on the clock frequency of the magnetic field, the cell temperature, and the laser intensities are reported. We show in particular that the laser intensity shift is temperature dependent. Along with the laser intensity ratio and laser polarization properties, this is one of the most important parameters.
Pulsed coherent population trapping (CPT) spectroscopy is applied in buffer-gas filled Cs–Ne vapor microfabricated cells. The properties of the Ramsey-CPT clock transition central fringe (linewidth, signal amplitude, and contrast) are studied versus several experimental parameters, including the Ramsey sequence and the input laser intensity, and are compared to those obtained in the conventional continuous (CW) interrogation mode. In the pulsed case and for short Ramsey-free evolution times TR, the central fringe linewidth is found to exhibit a small but visible power broadening and is measured to be narrower than the value of 1/(2TR) that is reached for long TR. The microwave hyperfine coherence lifetime T2 in the Cs–Ne microcells is measured to be in the 50–500 μs range. Its dependence to the buffer gas pressure or cell temperature is briefly studied.
This article reports on the development and short-term fractional frequency stability of a continuous-regime (CW) Cs vapor cell atomic clock based on coherent population trapping (CPT). The push-pull optical pumping technique is used to increase the number of atoms that participate to the clock transition, yielding a typical CPT resonance contrast of 25% for a CPT linewidth of about 450 Hz. The clock short-term fractional frequency stability is measured to be 3 x 10 -13 τ -1/2 up to 100 seconds averaging time, in correct agreement with the signal-to-noise ratio limit. The mid-term frequency stability results are currently mainly limited by laser power effects. The detection of high-contrast narrow Raman-Ramsey fringes is demonstrated with this setup by making the atoms interact with a light pulse sequence.
We propose a preliminary theoretical investigation and demonstrate experimentally the application of the autobalanced Ramsey (ABR) interrogation protocol onto a pulsed hot vapor Cs cell microwave atomic clock based on coherent population trapping (CPT). This approach, based on the alternation of two successive Ramsey-CPT sequences with unequal free-evolution times and the subsequent management oftwo interconnected phase and frequency servo loops, is found to allow a reduction of the clock frequency sensitivity to laser power variations. This approach, combined with the implementation of advanced electronics laser power stabilization systems, yields the demonstration of a CPT-based Cs cell clock with a fractional frequency stability at the level of 3.1 × 10−13 τ−1/2 and averaging down to the level of 7 ×10−15 at 2000 s integration time.