Improved Limits for Violations of Local Position Invariance from Atomic Clock Comparisons

Lange, R.; Huntemann, N.; Rahm, Johannes; Sanner, Christian; Shao, Hongxia; Lipphardt, B.; Tamm, Chr.; Weyers, S.; Peik, E.

doi:10.1103/physrevlett.126.011102

Cited by 159 publications

(110 citation statements)

References 41 publications

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“…Rosenband et al 2008). The most recent measurements constrain the time rate of change in α and µ to just (1.0 ± 1.1) × 10 −18 and (−8 ± 36) × 10 −18 yr −1 , respectively (Lange et al 2021). While it may be tempting to linearly extrapolate such constraints to cosmological time (and distance) scales, it should be emphasised that how the fundamental constants may vary, and on what they may depend, is entirely unknown; such extrapolations would be just as simplistic as assuming no variation at all.…”

Section: Introductionmentioning

confidence: 99%

Fundamental physics with ESPRESSO: Precise limit on variations in the fine-structure constant towards the bright quasar HE 0515−4414

Murphy

Molaro

Leite

et al. 2022

A&A

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The strong intervening absorption system at redshift 1.15 towards the very bright quasar HE 0515−4414 is the most studied absorber for measuring possible cosmological variations in the fine-structure constant, α. We observed HE 0515−4414 for 16.1 h with the Very Large Telescope and present here the first constraint on relative variations in α with parts-per-million (ppm) precision from the new ESPRESSO spectrograph: ∆α/α = 1.3 ± 1.3 stat ± 0.4 sys ppm. The statistical uncertainty (1σ) is similar to the ensemble precision of previous large samples of absorbers and derives from the high signal-to-noise ratio (S/N) achieved (≈105 per 0.4 km s −1 pixel). ESPRESSO's design, and the calibration of our observations with its laser frequency comb, effectively removed wavelength calibration errors from our measurement. The high resolving power of our ESPRESSO spectrum (R = 145000) enabled the identification of very narrow components within the absorption profile, allowing a more robust analysis of ∆α/α. The evidence for the narrow components is corroborated by their correspondence with previously detected molecular hydrogen and neutral carbon. The main remaining systematic errors arise from ambiguities in the absorption profile modelling, effects from redispersing the individual quasar exposures, and convergence of the parameter estimation algorithm. All analyses of the spectrum, including systematic error estimates, were initially blinded to avoid human biases. We make our reduced ESPRESSO spectrum of HE 0515−4414 publicly available for further analysis. Combining our ESPRESSO result with 28 measurements, from other spectrographs, in which wavelength calibration errors have been mitigated yields a weighted mean ∆α/α = −0.5 ± 0.5 stat ± 0.4 sys ppm at redshifts 0.6-2.4.

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Section: Introductionmentioning

confidence: 99%

Fundamental physics with ESPRESSO: Precise limit on variations in the fine-structure constant towards the bright quasar HE 0515−4414

Murphy

Molaro

Leite

et al. 2022

A&A

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“…Modern optical clocks operating at the 10 −18 level of relative instability and uncertainty 6 – 14 stimulate discussion about inevitable redefinition of the SI second 15 , 16 , which is also motivated by comparisons of different types of optical clocks at the 10 −17 level 6 , 7 , 17 , 18 . Such performance allows one to accurately test some fundamental physical theories: general relativity 19 , 20 , Lorentz invariance 21 , 22 , drifts of fundamental constants 23 , 24 , and the search for dark matter particles 25 and dark matter clusters 26 .…”

Section: Introductionmentioning

confidence: 99%

Simultaneous bicolor interrogation in thulium optical clock providing very low systematic frequency shifts

et al. 2021

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Optical atomic clocks have already overcome the eighteenth decimal digit of instability and uncertainty, demonstrating incredible control over external perturbations of the clock transition frequency. At the same time, there is an increasing demand for atomic (ionic) transitions and new interrogation and readout protocols providing minimal sensitivity to external fields and possessing practical operational wavelengths. One of the goals is to simplify the clock operation while maintaining the relative uncertainty at a low 10−18 level achieved at the shortest averaging time. This is especially important for transportable and envisioned space-based optical clocks. Here, we demonstrate implementation of a synthetic frequency approach for a thulium optical clock with simultaneous optical interrogation of two clock transitions. Our experiment shows suppression of the quadratic Zeeman shift by at least three orders of magnitude. The effect of the tensor lattice Stark shift in thulium can also be reduced to below 10−18 in fractional frequency units. This makes the thulium optical clock almost free from hard-to-control systematic shifts. The “simultaneous” protocol demonstrates very low sensitivity to the cross-talks between individual clock transitions during interrogation and readout.

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“…The performance of several optical clocks, using different atoms, have now surpassed that of the primary cesium frequency standard [2][3][4][5], which marks a significant advance toward a proposed redefinition of the second [6]. Optical clocks also have the potential to uncover new physics beyond the standard model at the high-precision, low-energy frontier, including searches for ultralight scalar dark matter [7], the time variation of fundamental constants [8,9], and violations of Einstein's equivalence principle [10]. In an effort to improve clock performance, atomic systems that are less sensitive to limiting systematic uncertainties such as Lu + [11] and Ba 4+ [12] have been proposed.…”

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confidence: 99%

“…Along with the expected clock performance, the radium ion has the largest positive enhancement to the time variation of the fine structure constant, κ Ra = 2.8, of any demonstrated clock [20]. The current constraint on α/α is derived from a frequency comparison between an optical clock based on the Yb + (E2) transition (τ ≈ 50 ms) and a second clock based on the Yb + (E3) transition [9]. Considering sensitivities of demonstrated clocks, the Yb + (E2) transition has the second largest positive enhancement to the time variation of the fine structure constant, κ E2 = 1, and the Yb + (E3) tran-sition has largest negative enhancement, κ E3 = −6.…”

mentioning

confidence: 99%

Radium Ion Optical Clock

Holliman,

Fan,

Contractor

et al. 2022

Preprint

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We report the first operation of a Ra + optical clock, a promising high-performance clock candidate. The clock uses a single trapped 226 Ra + ion and operates on the 7s 2 S 1/2 → 6d 2 D 5/2 electric quadrupole transition. By self-referencing three pairs of symmetric Zeeman transitions, we demonstrate a frequency instability of 1.1×10 −13 / √ τ , where τ is the averaging time in seconds. The total systematic uncertainty is evaluated to be ∆ν/ν = 9 × 10 −16 . Using the clock, we realize the first measurement of the ratio of the D 5/2 state to the S 1/2 state Landé g-factors: gD/gS = 0.598 805 3(11) A Ra + optical clock could improve limits on the time variation of the fine structure constant, α/α, in an optical frequency comparison. The ion also has several features that make it a suitable system for a transportable optical clock.

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Improved Limits for Violations of Local Position Invariance from Atomic Clock Comparisons

Cited by 159 publications

References 41 publications

Fundamental physics with ESPRESSO: Precise limit on variations in the fine-structure constant towards the bright quasar HE 0515−4414

Fundamental physics with ESPRESSO: Precise limit on variations in the fine-structure constant towards the bright quasar HE 0515−4414

Simultaneous bicolor interrogation in thulium optical clock providing very low systematic frequency shifts

Radium Ion Optical Clock

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