Low-Drift Coherent Population Trapping Clock Based on Laser-Cooled Atoms and High-Coherence Excitation Fields

Liu, Xiaochi; Ivanov, Eugene; Yudin, V. I.; Kitching, John; Donley, Elizabeth A.

doi:10.1103/physrevapplied.8.054001

Cited by 53 publications

(48 citation statements)

References 39 publications

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“…We characterize the CPT resonances in our system by measuring the steady-state transmission of the first pulse as a function of the LO frequency. We measure Ramsey-CPT fringes by integrating the initial transient in the second detection pulse, with laser intensity noise suppressed using a double-ratio method [29,30,33,42].…”

Section: Resultsmentioning

confidence: 99%

“…This leads to a sharp peak in the laser transmission, which can be used as a frequency reference, and the technique was important in the development of compact atomic clocks such as CSAC [15]. There are now several high-contrast CPT polarisation schemes including: lin lin [29,30], lin⊥lin [31], push-pull optical pumping (PPOP) [32], and σ + −σ − [33,34]. These techniques have been applied to both thermal vapour-cell and laser-cooled atoms.…”

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confidence: 99%

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Cold-atom clock based on a diffractive optic

et al. 2019

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Clocks based on cold atoms offer unbeatable accuracy and long-term stability, but their use in portable quantum technologies is hampered by a large physical footprint. Here, we use the compact optical layout of a grating magneto-optical trap (gMOT) for a precise frequency reference. The gMOT collects 10 7 87 Rb atoms, which are subsequently cooled to 20 µK in optical molasses. We optically probe the microwave atomic ground-state splitting using lin⊥lin polarised coherent population trapping and a Raman-Ramsey sequence. With ballistic drop distances of only 0.5 mm, the measured short-term fractional frequency stability is 2 × 10 −11 / √ τ , with prospects for 2 × 10 −13 / √ τ at the quantum projection noise limit.arXiv:1909.04361v1 [physics.atom-ph]

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Section: Resultsmentioning

confidence: 99%

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confidence: 99%

Cold-atom clock based on a diffractive optic

et al. 2019

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“…An elegant approach to reduce this major contribution is to probe the atoms with a pulsed Ramsey-CPT sequence 17 . This method allows the detection of narrow Ramsey-CPT fringes whose linewidth is mainly dependent on the free-evolution time and poorly affected by the a) Electronic mail: rodolphe.boudot@femto-st.fr power broadening and for which resonant light shifts scale inversely with the free-evolution time in the dark 15,18,19 . However, the Ramsey-CPT interrogation exhibits a nonnegligible residual sensitivity to light-shift effects.…”

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confidence: 99%

Symmetric autobalanced Ramsey interrogation for high-performance coherent-population-trapping vapor-cell atomic clock

Hafiz

Coget

Petersen

et al. 2018

Applied Physics Letters

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We report a high-performance pulsed coherent population trapping (CPT) Cs cell atomic clock using the implementation of a symmetric auto-balanced Ramsey (SABR) interrogation sequence. The latter method is found to reduce the light-power induced frequency shift by an order of magnitude compared to a previous experiment using a simple auto-balanced Ramsey interrogation. The contribution of this shift to the clock frequency stability is now rejected in the 10 −16 range at 10 4 s averaging time. Additional tricks, including a compensation method to reduce the laser AM noise contribution and the generation of novel error signals for LO frequency and phase correction, have been implemented using a FPGA-based digital electronics board in order to improve the clock short-term stability by a factor 2. The Allan deviation of the SABR-CPT clock, extracted from a selected 3 × 10 4 s-long dataset, is 2 × 10 −13 τ −1/2 and averages down to the level of 2.5 × 10 −15 at 10 4 s. These results are encouraging to stimulate the development of hot cell CPT-based clocks for industrial, scientific, and instrumentation applications.

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“…The value of the light shift is measured by the scaled frequency displacement . The DFJR method has been shown to suppress light shifts in the cold-atom CPT clock developed at NIST [13][14][15] by more than one order of magnitude [12] to the 1 × 10 −12 level or lower in our experiment. 1 = ⁄ 1 , was assumed to be 7 Hz (made large for illustrative purposes).…”

Section: Displaced Frequency Jump Ramseymentioning

confidence: 59%

Light-Shift Suppression with Novel Variants of Adaptive Ramsey Spectroscopy

Shuker

Pollock

Kitching

et al. 2019

2019 Joint Conference of the IEEE International Frequency Control Symposium and European Frequency and Time Forum (EFTF/IFC)

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We present a brief review of the rapidly growing field of autobalanced Ramsey spectroscopy followed by a detailed discussion and review of two novel techniques that were developed and tested in our laboratory: displaced frequency-jump Ramsey spectroscopy and combined error signal spectroscopy. These two techniques are related to, yet different from autobalanced Ramsey spectroscopy. The use of these techniques in a cold-atom clock based on coherent population trapping has reduced instabilities from variations in light-shift parameters by at least one order of magnitude. In each of these techniques the Ramsey sequence adapts to cancel light shifts and drifts.

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Low-Drift Coherent Population Trapping Clock Based on Laser-Cooled Atoms and High-Coherence Excitation Fields

Cited by 53 publications

References 39 publications

Cold-atom clock based on a diffractive optic

Cold-atom clock based on a diffractive optic

Symmetric autobalanced Ramsey interrogation for high-performance coherent-population-trapping vapor-cell atomic clock

Light-Shift Suppression with Novel Variants of Adaptive Ramsey Spectroscopy

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