Primary atomic frequency standards at NIST

Db, Sullivan; Jc, Bergquist; Jj, Bollinger; Re, Drullinger; Wm, Itano; Jefferts,; Wd, Lee; Meekhof, D. M.; Te, Parker; Fl, Walls; Dj, Wineland

doi:10.6028/jres.106.004

Cited by 24 publications

(15 citation statements)

References 38 publications

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“…The corresponding displacement vector for the general scenario (Ω k = Ω) is given via Eqs. (29) and (103) by…”

Section: Experiments On Earth or In Earth's Gravitational Fieldmentioning

confidence: 97%

“…The development of laser cooling techniques for neutral atoms was a crucial milestone on the road to precision atom interferometry which allowed longer interrogation times and narrower velocity distributions. Combining laser cooling with an atomic fountain configuration [28] enabled atomic clocks with longer times T between the two microwave π/2 pulses (with the frequency resolution ∆ν/ν being inversely proportional to T ) and a much larger number of Ramsey fringes (thanks to the narrower velocity spread), and the scheme has been employed in international standard time references based on microwave transitions ever since [29]. A similar set-up based on an atomic fountain using laser-cooled atoms together with a pair of counterpropagating Raman beams along the vertical direction was shown to have a great potential for precision accelerometry and gravimetry measurements [11].…”

Section: Early Developmentsmentioning

confidence: 99%

“…This perturbative solution for T fully determines the displacement vector χ n , see Eq. (29), and therefore the visibility (82) for a given interferometer geometry. Moreover, the displacement vector χ n and the expression for the generalized phase Φ n , Eq.…”

Section: Phase Shift and Visibility In Generalmentioning

confidence: 99%

“…( 19), determined by the recursive formula (22). The time-evolution matrix T at hand, it is straightforward to calculate all relevant quantities, for instance the displacement vector (29) or the generalized phase (27). To come familiar with the perturbative treatment, we apply our approach to different scenarios: (i) a constant gravity gradient as a simple example for interferometry in inertial reference frames (see the previous section and especially Eqs.…”

Section: Perturbative Treatment For Time-dependent Coefficientsmentioning

confidence: 99%

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Representation-free description of light-pulse atom interferometry including non-inertial effects

Kleinert¹,

Kajari²,

Roura³

et al. 2015

Physics Reports

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Light-pulse atom interferometers rely on the wave nature of matter and its manipulation with coherent laser pulses. They are used for precise gravimetry and inertial sensing as well as for accurate measurements of fundamental constants. Reaching higher precision requires longer interferometer times which are naturally encountered in microgravity environments such as drop-tower facilities, sounding rockets and dedicated satellite missions aiming at fundamental quantum physics in space. In all those cases, it is necessary to consider arbitrary trajectories and varying orientations of the interferometer set-up in non-inertial frames of reference.Here we provide a versatile representation-free description of atom interferometry entirely based on operator algebra to address this general situation. We show how to analytically determine the phase shift as well as the visibility of interferometers with an arbitrary number of pulses including the effects of local gravitational accelerations, gravity gradients, the rotation of the lasers and noninertial frames of reference. Our method conveniently unifies previous results and facilitates the investigation of novel interferometer geometries.

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“…The corresponding displacement vector for the general scenario (Ω k = Ω) is given via Eqs. (29) and (103) by…”

Section: Experiments On Earth or In Earth's Gravitational Fieldmentioning

confidence: 97%

Section: Early Developmentsmentioning

confidence: 99%

Section: Phase Shift and Visibility In Generalmentioning

confidence: 99%

Section: Perturbative Treatment For Time-dependent Coefficientsmentioning

confidence: 99%

See 2 more Smart Citations

Representation-free description of light-pulse atom interferometry including non-inertial effects

Kleinert¹,

Kajari²,

Roura³

et al. 2015

Physics Reports

View full text Add to dashboard Cite

show abstract

“…Atomic clocks exploiting the stability of Cs [5][6][7][8] or other atomic references [9][10][11][12][13] to stabilize an oscillator are known as the most precise timekeeping devices available, but constant performance gains are sought for technical and scientific applications.…”

mentioning

confidence: 99%

Analytically exploiting noise correlations inside the feedback loop to improve locked-oscillator performance

et al. 2016

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We introduce concepts from optimal estimation to the stabilization of precision frequency standards limited by noisy local oscillators. We develop a theoretical framework casting various measures for frequency standard variance in terms of frequency-domain transfer functions, capturing the effects of feedback stabilization via a time-series of Ramsey measurements. Using this framework we introduce a novel optimized hybrid predictive feedforward measurement protocol which employs results from multiple past measurements and transfer-function-based calculations of measurement covariance to improve the accuracy of corrections within the feedback loop. In the presence of common non-Markovian noise processes these measurements will be correlated in a calculable manner, providing a means to capture the stochastic evolution of the LO frequency during the measurement cycle. We present analytic calculations and numerical simulations of oscillator performance under competing feedback schemes and demonstrate benefits in both correction accuracy and long-term oscillator stability using hybrid feedforward. Simulations verify that in the presence of uncompensated dead time and noise with significant spectral weight near the inverse cycle time predictive feedforward outperforms traditional feedback, providing a path towards developing a new class of stabilization "software" routines for frequency standards limited by noisy local oscillators.High-performance passive frequency standards play a major role in technological applications such as network synchronization and GPS [1] as well as many fields of physical inquiry, including radioastronomy (very-longbaseline interferometry) [2], tests of general relativity [3], and particle physics [4]. Atomic clocks exploiting the stability of Cs [5][6][7][8] or other atomic references [9-13] to stabilize an oscillator are known as the most precise timekeeping devices available, but constant performance gains are sought for technical and scientific applications.In many settings, such as miniaturized deployable frequency standards or in GPS-denied environments, a major performance limitation aries from the quality of the local oscillator (LO) that probes and is locked to the atomic transition. The LO frequency may evolve randomly in time due to intrinsic noise processes in the underlying hardware [10,11], leading to time-varying deviations of the LO frequency from that of the stable atomic reference. These instabilities are partially compensated through use of a feedback protocol designed to transfer the stability of the reference to the LO, but their effects cannot be mitigated completely.Early work characterizing the so-called Dick effect [14] demonstrated that no matter how good the reference becomes, LO noise will still produce residual instabilities in the locked LO (LLO) through the feedback protocol itself. The dominant mechanism for this is evolution of the LO's frequency on timescales rapid compared with the shortest measurement and feedback cycle. Major contributors to this phenome...

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Atomic Clocks for GNSS

Hollberg

2020

Position, Navigation, and Timing Technologies in the 21st Century

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Primary atomic frequency standards at NIST

Cited by 24 publications

References 38 publications

Representation-free description of light-pulse atom interferometry including non-inertial effects

Representation-free description of light-pulse atom interferometry including non-inertial effects

Analytically exploiting noise correlations inside the feedback loop to improve locked-oscillator performance

Atomic Clocks for GNSS

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