Long term measurement of the<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:mmultiscripts><mml:mi>Sr</mml:mi><mml:mprescripts/><mml:none/><mml:mn>87</mml:mn></mml:mmultiscripts></mml:math>clock frequency at the limit of primary Cs clocks

Schwarz, Roman; Dörscher, S.; Al-Masoudi, A.; Benkler, E.; Legero, Thomas; Sterr, U.; Weyers, S.; Rahm, Johannes; Lipphardt, B.; Lisdat, Christian

doi:10.1103/physrevresearch.2.033242

Cited by 50 publications

(60 citation statements)

References 53 publications

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“… 62 , 63 . By the application of a cryogenic reference resonator 18 instead of a long room-temperature one 17 , 20 , a clock instability at has now been achieved 64 . A few hundred 87 Sr atoms are trapped in a nearly horizontally oriented lattice with a waist of 65 µm and a depth of about 80 E r .…”

Section: Methodsmentioning

confidence: 99%

Comparing ultrastable lasers at 7 × 10−17 fractional frequency instability through a 2220 km optical fibre network

et al. 2022

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Ultrastable lasers are essential tools in optical frequency metrology enabling unprecedented measurement precision that impacts on fields such as atomic timekeeping, tests of fundamental physics, and geodesy. To characterise an ultrastable laser it needs to be compared with a laser of similar performance, but a suitable system may not be available locally. Here, we report a comparison of two geographically separated lasers, over the longest ever reported metrological optical fibre link network, measuring 2220 km in length, at a state-of-the-art fractional-frequency instability of 7 × 10−17 for averaging times between 30 s and 200 s. The measurements also allow the short-term instability of the complete optical fibre link network to be directly observed without using a loop-back fibre. Based on the characterisation of the noise in the lasers and optical fibre link network over different timescales, we investigate the potential for disseminating ultrastable light to improve the performance of remote optical clocks.

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Section: Methodsmentioning

confidence: 99%

Comparing ultrastable lasers at 7 × 10−17 fractional frequency instability through a 2220 km optical fibre network

et al. 2022

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“…Synchronous acquisition avoids frequency offsets caused by drifts of the acquired signals and rejects noise from the transfer lasers and combs. The PPS signal and a 100 MHz reference are transmitted from the building housing the Yb + clock to the one housing the Sr clock, using high-quality rf cables (see also [5]).…”

Section: Frequency Combs and Linksmentioning

confidence: 99%

“…The laboratory strontium lattice clock at PTB has been described in previous publications [36,37,38,20,5]. We interrogate the (5s 2 ) 1 S 0 -(5s5p) 3 P 0 transition of a few hundred laser-cooled 87 Sr atoms that are confined in a nearly horizontal optical lattice.…”

Section: Sr Lattice Clockmentioning

confidence: 99%

“…While the definition of the SI base unit of time, the 'second', has remained essentially unchanged, there has been tremendous progress in time and frequency metrology over the past decades [2]. In particular, optical atomic clocks have surpassed primary realizations of the second in terms of frequency instability [3,4,5] and systematic uncertainty [6,7,8,9] by two orders of magnitude or more. Thus, the International Committee for Weights and Measures recommends standard frequency values of several atomic transitions [10] as Secondary Representations of the Second (SRS) [11].…”

Section: Introductionmentioning

confidence: 99%

“…They presently include nine transitions with fractional uncertainties between 4 × 10 −16 and 2 × 10 −15 ; eight of these are optical transitions [10]. Recently, measurements of transition frequencies with uncertainties near and even below 2 × 10 −16 have been reported for transitions in optical clocks using 171 Yb [12] and 87 Sr [5,13]. These absolute frequency measurements are limited by the uncertainty of the 133 Cs primary frequency standards (PFS) serving as the reference.…”

Section: Introductionmentioning

confidence: 99%

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Optical frequency ratio of a ${}^{171}\mathrm{Yb}^+$ single-ion clock and a ${}^{87}\mathrm{Sr}$ lattice clock

Dörscher,

Huntemann,

Schwarz

et al. 2020

Preprint

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We report direct measurements of the frequency ratio of the 642 THz 2 S 1/2 (F = 0)-2 F 7/2 (F = 3) electric octupole transition in 171 Yb + and the 429 THz 1 S 0 -3 P 0 transition in 87 Sr. A series of 107 measurements has been performed at the Physikalisch-Technische Bundesanstalt between December 2012 and October 2019. Long-term variations of the ratio are larger than expected from the individual measurement uncertainties of few 10 −17 . The cause of these variations remains unknown. Even taking these into account, we find a fractional uncertainty of the frequency ratio of 2.5 × 10 −17 , which improves upon previous knowledge by one order of magnitude. The average frequency ratio is ν Yb + /ν Sr = 1.495 991 618 544 900 537(38). This represents one of the most accurate measurements between two different atomic species to date.

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Estimation of Temporal Variations in the Earth’s Gravity Field Using Novel Optical Clocks Onboard of Low Earth Orbiters

Shabanloui,

Wu,

Müller

2023

International Association of Geodesy Symposia

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The current generation of optical atomic clocks has reached a fractional frequency uncertainty of 1$$\times $$ × 10$$^{-18}$$ − 18 (and beyond) which corresponds to a geopotential difference of 0.1 m$$^{2}$$ 2 /s$$^{2}$$ 2 . Those gravitational potential differences can be observed as gravitational redshift when comparing the frequencies of optical clocks. Even temporal potential variations might be determined with precise novel optical atomic clocks onboard of low-orbiting satellites such as SLR-like (e.g. LAGEOS-1/2) and GRACE-like missions.In this simulation study, the potential of precise space-borne optical clocks for the determination of temporal variations of low-degree Earth’s gravity field coefficients are investigated. Different configurations of satellite orbits, i.e. at different altitudes (between 400 and 6000 km) and inclinations, are selected as well as certain assumptions on the clock performance are made. A particular focus is put on how well degree-2 coefficients can be estimated from those optical clock measurements and how it compares to results from SLR.

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Long term measurement of theSr87clock frequency at the limit of primary Cs clocks

Cited by 50 publications

References 53 publications

Comparing ultrastable lasers at 7 × 10−17 fractional frequency instability through a 2220 km optical fibre network

Comparing ultrastable lasers at 7 × 10−17 fractional frequency instability through a 2220 km optical fibre network

Optical frequency ratio of a ${}^{171}\mathrm{Yb}^+$ single-ion clock and a ${}^{87}\mathrm{Sr}$ lattice clock

Estimation of Temporal Variations in the Earth’s Gravity Field Using Novel Optical Clocks Onboard of Low Earth Orbiters

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