Explanipedia

Coordinated international comparisons between optical clocks connected via fiber and satellite links Open

thomas lindvall, Marco Pizzocaro, rachel godun, Michel Abgrall, Daisuke Akamatsu , et al. · 2025

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…

Coulomb Crystal Clock with Systematic Uncertainty Open

H. N. Hausser, Jonas Keller, T. Nordmann, N. M. Bhatt, J. Kiethe , et al. · 2025

We present a scalable mixed-species Coulomb crystal clock based on the S01↔P30 transition in In+115. Yb+172 ions are cotrapped and used for…

High-accuracy multi-ion spectroscopy with mixed-species Coulomb crystals Open

Jonas Keller, H. N. Hausser, Ingo Richter, T. Nordmann, N. M. Bhatt , et al. · 2024

Multi-ion optical clocks offer the possibility of overcoming the low signal-to-noise ratio of single-ion clocks, while still providing low systematic uncertainties. We present simultaneous spectroscopy of up to four 115 In + clock ions in …

$^{115}$In$^+$-$^{172}$Yb$^+$ Coulomb crystal clock with $2.5\times10^{-18}$ systematic uncertainty Open

H. N. Hausser, Jonas Keller, T. Nordmann, N. M. Bhatt, J. Kiethe , et al. · 2024

We present a scalable mixed-species Coulomb crystal clock based on the $^1S_0$ $\leftrightarrow$ $^3P_0$ transition in $^{115}$In$^+$. $^{172}$Yb$^+$ ions are co-trapped and used for sympathetic cooling. Reproducible interrogation conditio…

Continuous optical generation of microwave signals for fountain clocks Open

B. Lipphardt, Patrick Walkemeyer, Michael Kazda, Johannes Rahm, S. Weyers · 2023

For the optical generation of ultrastable microwave signals for fountain clocks, we developed a setup based on a cavity stabilized laser and a commercial frequency comb. The robust system, in operation since 2020, is locked to a 100 MHz ou…

Evaluation of a Optical Clock with a Direct Measurement of the Blackbody Radiation Shift and Determination of the Clock Frequency Open

Martin Steinel, H. Shao, Melina Filzinger, B. Lipphardt, Malte Brinkmann , et al. · 2023

We report on an evaluation of an optical clock that uses the ^{2}S_{1/2}→^{2}D_{5/2} transition of a single ^{88}Sr^{+} ion as the reference. In contrast to previous work, we estimate the effective temperature of the blackbody radiation th…

Continuous optical generation of microwave signals for fountain clocks Open

B. Lipphardt, Patrick Walkemeyer, Michael Kazda, Johannes Rahm, S. Weyers · 2023

For the optical generation of ultrastable microwave signals for fountain clocks we developed a setup, which is based on a cavity stabilized laser and a commercial frequency comb. The robust system, in operation since 2020, is locked to a 1…

Path length stabilization in optical fibers using a superheterodyne receiver architecture Open

Michael Kazda, B. Lipphardt, Niklas Kuhrmeyer, Nils Huntemann · 2023

Microwave Interrogation signal generation system for PTB's caesium fountain clocks Open

Michael Kazda, B. Lipphardt, Johannes Rahm, S. Weyers · 2023

Evaluation of a $^{88}$Sr$^+$ optical clock with a direct measurement of the blackbody radiation shift and determination of the clock frequency Open

Martin Steinel, H. Shao, M. Filzinger, B. Lipphardt, Malte Brinkmann , et al. · 2022

We report on an evaluation of an optical clock that uses the $\phantom{}^2S_{1/2} \rightarrow \phantom{}^2D_{5/2}$ transition of a single $^{88}$Sr$^+$ ion as the reference. In contrast to previous work, we estimate the effective temperatu…

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

R. Lange, Nils Huntemann, Johannes Rahm, Christian Sanner, H. Shao , et al. · 2021

We compare two optical clocks based on the ^{2}S_{1/2}(F=0)→^{2}D_{3/2}(F=2) electric quadrupole (E2) and the ^{2}S_{1/2}(F=0)→^{2}F_{7/2}(F=3) electric octupole (E3) transition of ^{171}Yb^{+} and measure the frequency ratio ν_{E3}/ν_{E2}…

Optical frequency ratio of a 171Yb+ single-ion clock and a 87Sr lattice clock Open

Sören Dörscher, Nils Huntemann, R. Schwarz, R. Lange, Erik Benkler , et al. · 2020

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…

Coherent Suppression of Tensor Frequency Shifts through Magnetic Field Rotation Open

R. Lange, Nils Huntemann, Christian Sanner, H. Shao, B. Lipphardt , et al. · 2020

We introduce a scheme to coherently suppress second-rank tensor frequency shifts in atomic clocks, relying on the continuous rotation of an external magnetic field during the free atomic state evolution in a Ramsey sequence. The method ret…

Search for transient variations of the fine structure constant and dark matter using fiber-linked optical atomic clocks Open

B. M. Roberts, Pacôme Delva, Ali Al-Masoudi, A Amy-Klein, Christian Ørtoft Bærentsen , et al. · 2020

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…

End-to-end topology for fiber comb based optical frequency transfer at the 10−21 level: erratum Open

Erik Benkler, B. Lipphardt, Thomas Puppe, Rafał Wilk, Felix Rohde , et al. · 2020

In this erratum we correct errors in the scaling and caption of Fig. 4 in the original manuscript [1].

Direct comparisons of European primary and secondary frequency standards via satellite techniques Open

Franziska Riedel, Ali Al-Masoudi, E. Benkler, Sören Dörscher, Vladislav Gerginov , et al. · 2019

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…

Search for transient variations of the fine structure constant and dark\n matter using fiber-linked optical atomic clocks Open

B. M. Roberts, Pacôme Delva, Ali Al-Masoudi, Anne Amy‐Klein, Christian Ørtoft Bærentsen , et al. · 2019

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…

Advances in the accuracy, stability, and reliability of the PTB primary fountain clocks Open

S. Weyers, Vladislav Gerginov, Michael Kazda, Johannes Rahm, B. Lipphardt , et al. · 2018

Improvements of the systematic uncertainty, frequency instability, and long-term reliability of the two caesium fountain primary frequency standards CSF1 and CSF2 at PTB (Physikalisch-Technische Bundesanstalt) are described. We have furthe…

First international comparison of fountain primary frequency standards via a long distance optical fiber link Open

Jocelyne Guéna, S. Weyers, Michel Abgrall, Christian Grebing, Vladislav Gerginov , et al. · 2017

We report on the first comparison of distant caesium fountain primary frequency standards (PFSs) via an optical fiber link. The 1415 km long optical link connects two PFSs at LNE-SYRTE (Laboratoire National de métrologie et d'Essais—SYstèm…

Optical Stabilization of a Microwave Oscillator for Fountain Clock Interrogation Open

B. Lipphardt, Vladislav Gerginov, S. Weyers · 2017

We describe an optical frequency stabilization scheme of a microwave oscillator that is used for the interrogation of primary cesium fountain clocks. Because of its superior phase noise properties, this scheme, which is based on an ultrast…

Single-Ion Atomic Clock withSystematic Uncertainty Open

Nils Huntemann, Christian Sanner, B. Lipphardt, Chr. Tamm, E. Peik · 2016

We experimentally investigate an optical frequency standard based on the (2)S1/2(F=0)→(2)F7/2(F=3) electric octupole (E3) transition of a single trapped (171)Yb+ ion. For the spectroscopy of this strongly forbidden transition, we utilize a…

Phase Analysis for Frequency Standards in the Microwave and Optical Domains Open

Michael Kazda, Vladislav Gerginov, Nils Huntemann, B. Lipphardt, S. Weyers · 2016

Coherent manipulation of atomic states is a key concept in high-precision spectroscopy and used in atomic fountain clocks and a number of optical frequency standards. Operation of these standards can involve a number of cyclic switching pr…

Realization of a time-scale with an optical clock Open

Christian Grebing, Ali Al-Masoudi, Sören Dörscher, Sebastian Häfner, Vladislav Gerginov , et al. · 2015

Optical clocks are not only powerful tools for prime fundamental research, but are also deemed for the re-definition of the SI base unit second as they surpass the performance of caesium atomic clocks in both accuracy and stability by more…

Frequency comparison of ${}^{171}$Yb${}^+$ ion optical clocks at PTB and NPL via GPS PPP Open

J. Leute, Nils Huntemann, B. Lipphardt, Chr. Tamm, Peter B. R. Nisbet-Jones , et al. · 2015

We used Precise Point Positioning, a well-established GPS carrier-phase frequency transfer method to perform a direct remote comparison of two optical frequency standards based on single laser-cooled $^{171}$Yb$^+$ ions operated at NPL, UK…

B. Lipphardt YOU? Author Swipe