Project B02: Optical clocks testing fundamental physics

In this project we will investigate and implement methods to circumvent limitations in accuracy and stability using both an operational strontium lattice clock and a more flexible setup with ultracold calcium. With these optical clocks we will investigate fundamental questions of the temporal and spatial stability of e.g. the fine structure constant α and its potential couplings to dark matter. Specifically tailored motional quantum states shall be used to identify and minimize motion-related clock uncertainties. To address limitations from the linewidth of the interrogation laser, which is in fact limiting the stability of most ion and neutral atom clocks, we will in parallel investigate an active optical frequency source based on super-fluorescence on a narrow clock transition.

Introduction

Supported by their ever-improving precision, optical clocks have been employed over the past two decades to perform some of the most stringent tests of fundamental physical principles. Following this idea, the goal of this project is to employ high-performance optical clocks to search for violations of the predictions of the standard model of particle physics, commonly referred to as new-physics effects.

Results

Towards this goal, we have tested local position invariance (LPI) by repeatedly comparing the output of atomic clocks realizing different clock transition frequencies. The different sensitivities of the involved atomic states to fundamental constants, such as the fine-structure constant α or the proton-to-electron mass ratio μ, allows us to either identify the corresponding violating constant or to constrain its instability. Within DQ-mat, we have recently established the most stringent bounds on temporal variations and a potential coupling to gravity for α and μ. These investigations profited in particular from the high sensitivity of the clock transitions of the Yb+ ion to variations of α.

To perform reliable tests and to further push the limits of our searches for new-physics effects, we have improved the understanding of frequency shifts resulting from blackbody radiation and the lattice laser light for the Sr clock, which aided to resolve a discrepancy between experimentally and theoretically determined atomic parameters and lead to a better understanding of the atomic structure of Sr. We have started to operate a Yb+ ion clock setup in which 88Sr+ can be employed as ancillary ion, e.g., to measure the perturbing thermal radiation. The latter investigation has also helped to resolve a serious tension in recent measurements of the 88Sr+ clock transition frequency.

Both systems, the 87Sr lattice clock and the 171Yb+ ion clock, have also been employed in long-term frequency comparisons and to search for another new-physics curiosity: dark matter.

Publications

Showing results 1 - 20 out of 23

Dörscher S, Klose J, Maratha palli S, Lisdat C. Experimental determination of the E2−M1 polarizability of the strontium clock transition. Physical Review Research. 2023 Feb 7;5(1):L012013. doi: 10.1103/PhysRevResearch.5.L012013
Filzinger M, Dörscher S, Lange R, Klose J, Steinel M, Benkler E et al. Improved limits on the coupling of ultralight bosonic dark matter to photons from optical atomic clock comparisons. Physical Review Letters. 2023 Jun 22;130(25):253001. doi: 10.48550/arXiv.2301.03433, 10.1103/PhysRevLett.130.253001
Kedar D, Yu J, Oelker E, Staron A, Milner WR, Robinson JM et al. Frequency stability of cryogenic silicon cavities with semiconductor crystalline coatings. OPTICA. 2023 Apr 20;10(4):464-470. doi: 10.1364/OPTICA.479462
Peshkov AA, Bidasyuk YM, Lange R, Huntemann N, Peik E, Surzhykov A. Interaction of twisted light with a trapped atom: Interplay between electronic and motional degrees of freedom. Physical Review A. 2023 Feb 13;107(2):023106. doi: 10.1103/physreva.107.023106
Steinel M, Shao H, Filzinger M, Lipphardt B, Brinkmann M, Didier A et al. Evaluation of a Sr+ 88 Optical Clock with a Direct Measurement of the Blackbody Radiation Shift and Determination of the Clock Frequency. Physical review letters. 2023 Aug 23;131(8):083002. doi: 10.1103/PhysRevLett.131.083002
Kazakov GA, Dubey S, Bychek A, Sterr U, Bober M, Zawada M. Ultimate stability of active optical frequency standards. Physical Review A. 2022 Nov 23;106(5):053114. doi: 10.48550/arXiv.2205.14130, 10.1103/PhysRevA.106.053114
Lange R, Huntemann N, Peshkov AA, Surzhykov A, Peik E. Excitation of an Electric Octupole Transition by Twisted Light. Physical review letters. 2022 Dec 12;129(25):253901. doi: 10.1103/PhysRevLett.129.253901
Schioppo M, Kronjäger J, Silva A, Ilieva R, Paterson JW, Baynham CFA et al. Comparing ultrastable lasers at 7 × 10−17 fractional frequency instability through a 2220 km optical fibre network. Nature Communications. 2022 Jan 11;13(1):212. doi: 10.1038/s41467-021-27884-3
Steinel M, Shao H, Filzinger M, Lipphardt B, Brinkmann M, Didier A et al. Evaluation of a 88Sr+ optical clock with a direct measurement of the blackbody radiation shift and determination of the clock frequency. 2022 Dec 16. Epub 2022 Dec 16. doi: 10.48550/arXiv.2212.08687
Dörscher S, Huntemann N, Schwarz R, Lange R, Benkler E, Lipphardt B et al. Optical frequency ratio of a 171Yb+ single-ion clock and a 87Sr lattice clock. METROLOGIA. 2021 Feb;58(1):015005. doi: 10.1088/1681-7575/abc86f
Lange R, Huntemann N, Rahm JM, Sanner C, Shao H, Lipphardt B et al. Improved Limits for Violations of Local Position Invariance from Atomic Clock Comparisons. Physical review letters. 2021 Jan 6;126(1):011102. doi: 10.1103/PhysRevLett.126.011102
Lisdat C, Dörscher S, Nosske I, Sterr U. Blackbody radiation shift in strontium lattice clocks revisited. Physical Review Research. 2021 Dec 9;3(4):L042036. doi: 10.1103/physrevresearch.3.l042036
Dörscher S, Al-Masoudi A, Bober M, Schwarz R, Hobson R, Sterr U et al. Dynamical decoupling of laser phase noise in compound atomic clocks. Communications Physics. 2020 Dec 1;3(1):185. doi: 10.1038/s42005-020-00452-9
Roberts BM, Delva P, Al-Masoudi A, Amy-Klein A, Bærentsen C, Baynham CFA et al. Search for transient variations of the fine structure constant and dark matter using fiber-linked optical atomic clocks. New journal of physics. 2020 Sept;22(9):093010. doi: 10.1088/1367-2630/abaace
Schulte M, Lisdat C, Schmidt PO, Sterr U, Hammerer K. Prospects and challenges for squeezing-enhanced optical atomic clocks. Nature Communications. 2020 Nov 24;11(1):5955. doi: 10.1038/s41467-020-19403-7
Schwarz R, Dörscher S, Al-Masoudi A, Benkler E, Legero T, Sterr U et al. Long term measurement of the Sr 87 clock frequency at the limit of primary Cs clocks. Physical Review Research. 2020 Aug;2(3):033242. doi: 10.1103/PhysRevResearch.2.033242
Herbers S, Dörscher S, Benkler E, Lisdat C. Phase noise of frequency doublers in optical clock lasers. Optics express. 2019;27(16):23262-23273. doi: 10.1364/OE.27.023262
Schwarz R, Dörscher S, Al-Masoudi A, Vogt S, Li Y, Lisdat C. A compact and robust cooling laser system for an optical strontium lattice clock. Review of scientific instruments. 2019 Feb 25;90(2):023109. doi: 10.1063/1.5063552
Dörscher S, Schwarz R, Al-Masoudi A, Falke S, Sterr U, Lisdat C. Lattice-induced photon scattering in an optical lattice clock. Physical Review A. 2018 Jun 25;97(6):063419. doi: 10.1103/PhysRevA.97.063419
Mehlstäubler TE, Grosche G, Lisdat C, Schmidt PO, Denker H. Atomic clocks for geodesy. Reports on Progress in Physics. 2018 Jun;81(6):064401. Epub 2018 Apr 18. doi: 10.48550/arXiv.1803.01585, 10.1088/1361-6633/aab409
All publications of the Collaborative Research Centre

Project leader

Dr. Nils Huntemann
Address
Bundesallee 100
38116 Braunschweig
Dr. Nils Huntemann
Address
Bundesallee 100
38116 Braunschweig
PD Dr. Christian Lisdat
Address
Bundesallee 100
38116 Braunschweig
PD Dr. Christian Lisdat
Address
Bundesallee 100
38116 Braunschweig

Staff

Dr. Sören Dörscher
Address
Bundesallee 100
D-38116 Braunschweig
Dr. Sören Dörscher
Address
Bundesallee 100
D-38116 Braunschweig