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View article: Transportable strontium lattice clock with <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:mrow> <mml:mn>4</mml:mn> <mml:mo>×</mml:mo> <mml:msup> <mml:mn>10</mml:mn> <mml:mrow> <mml:mo>−</mml:mo> <mml:mn>19</mml:mn> </mml:mrow> </mml:msup> </mml:mrow> </mml:math> blackbody radiation shift uncertainty
Transportable strontium lattice clock with blackbody radiation shift uncertainty Open
We describe a transportable optical lattice clock based on the transition of lattice-trapped 87 Sr atoms with a total systematic uncertainty of . The blackbody radiation shift, which is the leading systematic effect i…
View article: Transportable strontium lattice clock with $4 \times 10^{-19}$ blackbody radiation shift uncertainty
Transportable strontium lattice clock with $4 \times 10^{-19}$ blackbody radiation shift uncertainty Open
We describe a transportable optical lattice clock based on the $^1\mathrm{S}_0 \rightarrow {^3\mathrm{P}_0}$ transition of lattice-trapped $^{87}$Sr atoms with a total systematic uncertainty of $2.1 \times 10^{-18}$. The blackbody radiatio…
View article: Entanglement-enhanced optical ion clock
Entanglement-enhanced optical ion clock Open
Entangled states hold the promise of improving the precision and accuracy of quantum sensors. We experimentally demonstrate that spectroscopy of an optical clock transition using entangled states can outperform its classical counterpart. T…
View article: Coordinated international comparisons between optical clocks connected via fiber and satellite links
Coordinated international comparisons between optical clocks connected via fiber and satellite links Open
Optical clocks provide ultraprecise frequency references that are vital for international metrology as well as for tests of fundamental physics. To investigate the level of agreement between different clocks, we simultaneously measured the…
View article: <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:mrow><mml:mmultiscripts><mml:mrow><mml:msup><mml:mrow><mml:mi>In</mml:mi></mml:mrow><mml:mrow><mml:mo>+</mml:mo></mml:mrow></mml:msup></mml:mrow><mml:mprescripts/><mml:none/><mml:mrow><mml:mn>115</mml:mn></mml:mrow></mml:mmultiscripts><mml:mtext>−</mml:mtext><mml:mrow><mml:mmultiscripts><mml:mrow><mml:msup><mml:mrow><mml:mi>Yb</mml:mi></mml:mrow><mml:mrow><mml:mo>+</mml:mo></mml:mrow></mml:msup></mml:mrow><mml:mprescripts/><mml:none/><mml:mrow><mml:mn>172</mml:mn></mml:mrow></mml:mmultiscripts></mml:mrow></mml:mrow></mml:math> Coulomb Crystal Clock with <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:mrow><mml:mn>2.5</mml:mn><mml:mo>×</mml:mo><mml:msup><mml:mrow><mml:mn>10</mml:mn></mml:mrow><mml:mrow><mml:mo>−</mml:mo><mml:mn>18</mml:mn></mml:mrow></mml:msup></mml:mrow></mml:math> Systematic Uncertainty
Coulomb Crystal Clock with Systematic Uncertainty Open
We present a scalable mixed-species Coulomb crystal clock based on the S0
View article: Robust Optical Clocks for International Timescales (ROCIT)
Robust Optical Clocks for International Timescales (ROCIT) Open
The recently concluded collaborative European project “Robust optical clocks for international timescales” (ROCIT) tackled some of the key challenges on the roadmap towards a redefinition of the SI second. This paper gives an overview of p…
View article: International comparison of optical frequencies with transportable optical lattice clocks
International comparison of optical frequencies with transportable optical lattice clocks Open
Optical clocks have improved their frequency stability and estimated accuracy by more than two orders of magnitude over the best caesium microwave clocks that realise the SI second. Accordingly, an optical redefinition of the second has be…
View article: Long-distance chronometric leveling with a portable optical clock
Long-distance chronometric leveling with a portable optical clock Open
We have measured the geopotential difference between two locations separated by 457 km by comparison of two optical lattice clocks via an interferometric fiber link, utilizing the gravitational redshift of the clock transition frequency. T…
View article: Long-distance chronometric leveling with a portable optical clock
Long-distance chronometric leveling with a portable optical clock Open
We have measured the geopotential difference between two locations separated by $457~\mathrm{km}$ by comparison of two optical lattice clocks via an interferometric fiber link, utilizing the gravitational redshift of the clock transition f…
View article: Experimental determination of the <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:mrow><mml:mi>E</mml:mi><mml:mn>2</mml:mn><mml:mtext>−</mml:mtext><mml:mi>M</mml:mi><mml:mn>1</mml:mn></mml:mrow></mml:math> polarizability of the strontium clock transition
Experimental determination of the polarizability of the strontium clock transition Open
To operate an optical lattice clock at a fractional uncertainty below 10^{−17}, one must typically consider not only electric-dipole (E1) interaction between an atom and the lattice light field when characterizing the resulting lattice lig…
View article: USOQS guideline document
USOQS guideline document Open
This document intends to summarize some of the results achieved within the project named Ultra-Stable Optical oscillators from Quantum coherent and entangled Systems (USOQS), to provide a guideline highlighting successes and pit fall we fa…
View article: Experimental determination of the E2-M1 polarizability of the strontium clock transition
Experimental determination of the E2-M1 polarizability of the strontium clock transition Open
To operate an optical lattice clock at a fractional uncertainty below $10^{-17}$, one must typically consider not only electric-dipole (E1) interaction between an atom and the lattice light field when characterizing the resulting lattice l…
View article: A transportable clock laser system with an instability of $1.6 \times 10^{-16}$
A transportable clock laser system with an instability of $1.6 \times 10^{-16}$ Open
We present a transportable ultra-stable clock laser system based on a Fabry-Pérot cavity with crystalline Al$_{0.92}$Ga$_{0.08}$As/GaAs mirror coatings, fused silica (FS) mirror substrates and a 20~cm-long ultra-low expansion (ULE\textsupe…
View article: Data for "Comparing ultrastable lasers at 7×10-17 fractional frequency instability through a 2220 km optical fibre network"
Data for "Comparing ultrastable lasers at 7×10-17 fractional frequency instability through a 2220 km optical fibre network" Open
Here we share the relevant data of the manuscript “Comparing ultrastable lasers at 7×10-17 fractional frequency instability through a 2,220 km optical fibre network”. Raw data was acquired using multiple synchronised, dead-time …
View article: Data for "Comparing ultrastable lasers at 7×10-17 fractional frequency instability through a 2220 km optical fibre network"
Data for "Comparing ultrastable lasers at 7×10-17 fractional frequency instability through a 2220 km optical fibre network" Open
Here we share the relevant data of the manuscript “Comparing ultrastable lasers at 7×10-17 fractional frequency instability through a 2,220 km optical fibre network”. Raw data was acquired using multiple synchronised, dead-time …
View article: Blackbody radiation shift in strontium lattice clocks revisited
Blackbody radiation shift in strontium lattice clocks revisited Open
We reevaluate the blackbody radiation (BBR) induced ac-Stark shift of the strontium clock transition (5s5p)^{3}P_{0}-(5s^{2})^{1}S_{0} at 698nm used as reference in optical lattice clocks and as secondary representation of the SI unit “sec…
View article: Optical frequency ratio of a <sup>171</sup>Yb<sup>+</sup> single-ion clock and a <sup>87</sup>Sr lattice clock
Optical frequency ratio of a <sup>171</sup>Yb<sup>+</sup> single-ion clock and a <sup>87</sup>Sr lattice clock Open
We report direct measurements of the frequency ratio of the 642 THz electric octupole transition in 171 Yb + and the 429 THz transition in 87 Sr. A series of 107 measurements has been perfo…
View article: Dynamical decoupling of laser phase noise in compound atomic clocks
Dynamical decoupling of laser phase noise in compound atomic clocks Open
The frequency stability of many optical atomic clocks is limited by the coherence of their local oscillator. Here, we present a measurement protocol that overcomes the laser coherence limit. It relies on engineered dynamical decoupling of …
View article: Search for transient variations of the fine structure constant and dark matter using fiber-linked optical atomic clocks
Search for transient variations of the fine structure constant and dark matter using fiber-linked optical atomic clocks Open
We search for transient variations of the fine structure constant using data from a European network of fiber-linked optical atomic clocks. By searching for coherent variations in the recorded clock frequency comparisons across the network…
View article: Dynamic decoupling of laser phase noise in compound atomic clocks
Dynamic decoupling of laser phase noise in compound atomic clocks Open
The frequency stability achieved by an optical atomic clock ultimately depends on the coherence of its local oscillator. Even the best ultrastable lasers only allow interrogation times of a few seconds, at present. Here we present a univer…
View article: Direct comparisons of European primary and secondary frequency standards via satellite techniques
Direct comparisons of European primary and secondary frequency standards via satellite techniques Open
We carried out a 26-day comparison of five simultaneously operated optical clocks and six atomic fountain clocks located at INRIM, LNE-SYRTE, NPL and PTB by using two satellite-based frequency comparison techniques: broadband Two-Way Satel…
View article: Phase noise of frequency doublers in optical clock lasers
Phase noise of frequency doublers in optical clock lasers Open
Frequency doublers are widely used in high-resolution spectroscopy to shift the operation wavelength of a laser to a more easily accessible or otherwise preferable spectral region. We investigate the use of a periodically-poled lithium nio…
View article: Search for transient variations of the fine structure constant and dark\n matter using fiber-linked optical atomic clocks
Search for transient variations of the fine structure constant and dark\n matter using fiber-linked optical atomic clocks Open
We search for transient variations of the fine structure constant using data\nfrom a European network of fiber-linked optical atomic clocks. By searching for\ncoherent variations in the recorded clock frequency comparisons across the\nnetw…
View article: Guidelines for developing optical clocks with $10^{-18}$ fractional frequency uncertainty
Guidelines for developing optical clocks with $10^{-18}$ fractional frequency uncertainty Open
There has been tremendous progress in the performance of optical frequency standards since the first proposals to carry out precision spectroscopy on trapped, single ions in the 1970s. The estimated fractional frequency uncertainty of toda…
View article: Guidelines for developing optical clocks with 10-18 fractional frequency uncertainty
Guidelines for developing optical clocks with 10-18 fractional frequency uncertainty Open
There has been tremendous progress in the performance of optical frequency standards since the first proposals to carry out precision spectroscopy on trapped, single ions in the 1970s. The estimated fractional frequency uncertainty of toda…
View article: Towards an optical clock for space: Compact, high-performance optical lattice clock based on bosonic atoms
Towards an optical clock for space: Compact, high-performance optical lattice clock based on bosonic atoms Open
Optical lattice clocks with uncertainty and instability in the\n$10^{-17}$-range and below have so far been demonstrated exclusively using\nfermions. Here, we demonstrate a bosonic optical lattice clock with $3\\times\n10^{-18}$ instabilit…
View article: Lattice-induced photon scattering in an optical lattice clock
Lattice-induced photon scattering in an optical lattice clock Open
We investigate scattering of lattice laser radiation in a strontium optical\nlattice clock and its implications for operating clocks at interrogation times\nup to several tens of seconds. Rayleigh scattering does not cause significant\ndec…
View article: Test of Special Relativity Using a Fiber Network of Optical Clocks
Test of Special Relativity Using a Fiber Network of Optical Clocks Open
Phase compensated optical fiber links enable high accuracy atomic clocks separated by thousands of kilometers to be compared with unprecedented statistical resolution. By searching for a daily variation of the frequency difference between …
View article: Transportable Optical Lattice Clock with<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:mn>7</mml:mn><mml:mo>×</mml:mo><mml:msup><mml:mn>10</mml:mn><mml:mrow><mml:mo>−</mml:mo><mml:mn>17</mml:mn></mml:mrow></mml:msup></mml:math>Uncertainty
Transportable Optical Lattice Clock withUncertainty Open
We present a transportable optical clock (TOC) with ^{87}Sr. Its complete characterization against a stationary lattice clock resulted in a systematic uncertainty of 7.4×10^{-17}, which is currently limited by the statistics of the determi…
View article: A clock network for geodesy and fundamental science
A clock network for geodesy and fundamental science Open