Establish fiber-based optical clock networks, improve optical clocks and frequency transfer techniques, exploit chronometric levelling for geodesy.
Contributions to QuantumFrontiers
- The optical fibre link between PTB and LUH is the backbone infrastructure for enabling new and accurate measurement capabilities for researchers in geodesy, atomic physics and quantum communication
- Coordination of measurement campaigns between clocks for the investigation of e.g., frequency ratios in highly charged ions, dark matter, chronometric levelling in geodesy and quantum communication protocols
- Advancement and development of the clock and related technologies to be broadly applicable
- Development and validation of the measurement equipment that is used to test our physical understanding by precision spectroscopy
Collaborative Innovation
- Developing hardware that is common in all clocks, e.g. FPGA-based locks, autonomous laser operation (Ch. Lisdat (PTB), P.O. Schmidt (PTB/LUH), T. Mehlstäubler (PTB/LUH), J. Keller (PTB), E. Brenkler (PTB), U. Sterr (PTB), G. Grosche (PTB), A. Kuhl (PTB))
- Advancing data analysis strategies e.g., the development of data structures that are interchangeable with international partners and the interpretation of data to validate individual clocks (J. Kronjäger (PTB), E. Benkler (PTB), S. Koke (PTB), J. Keller (PTB))
- Developing strategies to best exploit the available and future fiber links and clock infrastructure for e.g. chronometric levelling (J. Kronjäger (PTB), Ch. Lisdat (PTB), T. Liebisch (PTB), T. Mehlstäubler (PTB), S. Koke (PTB), G. Grosche (PTB), A. Kuhl (PTB), J. Müller (LUH), S. Schön (LUH))
- Achieving an inaccuracy and an instability of stationary optical clocks to be reliably below the level of 1 part in 1018 (Ch. Lisdat (PTB), P.O. Schmidt (PTB/LUH), T. Mehlstäubler (PTB/LUH), J. Keller (PTB), D. Nicolodi (PTB), C. Vishwakarma (PTB), S. Sauer (TUBS))
- Advancing today’s optical clocks from prototype status to more reliable, rugged, transportable and miniaturized devices (Ch. Lisdat (PTB), P.O. Schmidt (PTB/LUH), T. Mehlstäubler (PTB/LUH), J. Keller (PTB), C. Vishwakarma (PTB), U. Sterr (PTB))
- Confirming inaccuracy and instability of interferometric fibre links in the 10-19 to 10-20 regime (J. Kronjäger (PTB), S. Koke (PTB), J. Ji (PTB), E. Benkler (PTB), G. Grosche (PTB), A. Kuhl (PTB))
- Investigating the coherent, low-noise frequency conversion in optical frequency combs (E. Benkler (PTB), U. Sterr (PTB))
- Investigating link non-reciprocality and relativistic effects (E. Hackmann (ZARM), C. Lämmerzahl (ZARM), D. Philipp (ZARM), J. Kronjäger (PTB), G. Grosche (PTB))
- Investigating coherent free-space frequency transfer (S. Koke (PTB), J. Ji (PTB), J. Kronjäger (PTB))
- Develop methods and instrumentation for simultaneous quantum communication and time & frequency dissemination via optical fibres (J. Kronjäger (PTB), G. Grosche (PTB), A. Kuhl (PTB), S. Kück (PTB), F. Ding LUH))
Scientific Output
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Publications
Bondza SA, Leopold T, Schwarz R, Lisdat C. Achromatic, planar Fresnel-reflector for a single-beam magneto-optical trap. Review of scientific instruments. 2024 Jan 25;95(1):013202. doi: 10.1063/5.0174674Grotti J, Nosske I, Koller SB, Herbers S, Denker H, Timmen L et al. Long-distance chronometric leveling with a portable optical clock. Physical review applied. 2024 Jun 3;21(6):L061001. doi: 10.1103/PhysRevApplied.21.L061001Dörscher 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.L012013Filzinger 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. 253001. doi: 10.48550/arXiv.2301.03433, 10.1103/PhysRevLett.130.253001Bondza S, Lisdat C, Kroker S, Leopold T. Two-Color Grating Magneto-Optical Trap for Narrow-Line Laser Cooling. Physical review applied. 2022 Apr 1;17(4):044002. doi: 10.1103/physrevapplied.17.044002Herbers S, Häfner S, Dörscher S, Lücke T, Sterr U, Lisdat C. Transportable clock laser system with an instability of 1.6 × 10-16. Optics letters. 2022 Oct 15;47(20):5441-5444. doi: 10.1364/OL.470984Schioppo 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/s41467-021-27884-3Dörscher 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/abc86fPelzer L, Dietze K, Kramer J, Dawel F, Krinner L, Spethmann N et al. Tailored optical clock transition in 40Ca+. Measurement: Sensors. 2021 Dec;18:100326. Epub 2021 Sept 30. doi: 10.1016/j.measen.2021.100326Micke P, Leopold T, King SA, Benkler E, Spieß LJ, Schmöger L et al. Coherent laser spectroscopy of highly charged ions using quantum logic. NATURE. 2020 Feb 6;578:60-65. Epub 2020 Jan 29. doi: 10.48550/arXiv.2010.15984, 10.1038/s41586-020-1959-8Porsev SG, Safronova UI, Safronova MS, Schmidt PO, Bondarev AI, Kozlov MG et al. Optical clocks based on the Cf15+ and Cf17+ ions. Physical Review A. 2020 Jul 6;102(1):012802. doi: 10.48550/arXiv.2004.05978, 10.1103/PhysRevA.102.012802Schulte 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/s41467-020-19403-7Wu H, Müller J, Lämmerzahl C. Clock networks for height system unification: A simulation study. Geophysical journal international. 2018 Nov 28;216(3):1594-1607. doi: 10.1093/gji/ggy508
TG Members
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Involved Members and their Relevant Expertise
Members Institution Relevant Expertise Christian Lisdat, Leader PTB Sr Optical Lattice Clock Gesine Grosche PTB Free-Space Frequency Transfer; Frequency Transfer Techniques Alexander Kuhl PTB Free-Space Frequency Transfer Chetan Vishwakarma PTB Sr Optical Lattice Clock Jürgen Müller LUH Relativistic Geodesy; LLR Relativity Test; Application of Quantum Gravimetry Piet O. Schmidt PTB / LUH Quantum Logic Spectroscopy of Highly Charged Ions; Stationary and transportable Al+ Clocks Claus Lämmerzahl ZARM Quantum Sensors in Free Fall; Relativistic Geodesy; Quantum Objects in Gravity Steffen Sauer TUBS Ultra-stable cavities for optical clocks Tara Liebisch PTB Clock Network Schemes Ernst M. Rasel LUH Quantum Gravimeters; Atom-Chip Based Gravimeters and Inertial Sensors Stefanie Kroker PTB / TUBS Complex Coupled High Index Waveguide Arrays; Photonic Nanomaterials in the Strong Optomechanical Coupling Regime Dennis Philipp ZARM General Relativity, relativistic geodesy Eva Hackmann ZARM General Relativity, relativistic geodesy Steffen Schön LUH GNSS Frequency Transfer Sebastian Koke PTB Frequency Transfer Techniques Jingxian Ji PTB Free-Space Frequency Transfer Akbar Shabanloui LUH Gravity field modelling, clock networks, height systems, precise satellite orbit determination Jochen Kronjäger PTB Free-Space Frequency Transfer; Frequency Transfer Techniques Tanja Mehlstäubler PTB / LUH Single and multi-ion clocks Jonas Keller PTB Single and multi-ion clocks Erik Benkler PTB Optical frequency combs Uwe Sterr PTB Ultra-stable lasers and optical frequency combs Daniele Nicolodi PTB Ultra-stable lasers Stefan Kück PTB Single photons and quantum communication Fei Ding LUH Quantum communication Nils Huntemann PTB Ekkehard Peik PTB Shuying Chen PTB Carsten Klempt LUH Johannes Kramer PTB Lennart Pelzer PTB