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Atomic Clocks Physical Seminar - Quantum Optics and Nanophotonics -

Atomic Clocks Physical Seminar - Quantum Optics and Nanophotonics -. Peter Deiml 20.05.2014. Table of contents. Why do we need an exact definition of time? Current time standard Spectroscopy Ramsey-Spectroscopy Caesium beam clock (Laser Cooling) Caesium fountain clock

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Atomic Clocks Physical Seminar - Quantum Optics and Nanophotonics -

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  1. Atomic Clocks Physical Seminar - Quantum Optics and Nanophotonics - Peter Deiml 20.05.2014

  2. Table ofcontents • Why do we need an exact definition of time? • Current time standard • Spectroscopy • Ramsey-Spectroscopy • Caesium beam clock • (Laser Cooling) • Caesium fountain clock • Outlook: Optical Clock Quantum Optics and Nanophotonics Atomic Clocks Peter Deiml

  3. Why do weneed an exactdefinitionof time? [Bauch, 2003],[Bauch, 2012] “The accurate measurement of time and frequency is vital to the success of many fields of science and technology.” [Bauch, 2003] • Somescientificexamples: • Other SI-units (e.g. meter) based upon thesecond • Spectrumofatoms(QM,QED) • „Proof“ ofequivalenceprinciple, SR, GR (Hafele-Keating-/ Maryland-experiment) • Gravitationalwaves • Fine structureconstantconstant? • Someeverydayexamples: • Global Positioning System (GPS) • Telecommunication • Supply ofenergy Fig. 2: NAVSTAR satellite [Wiki GPS, 2014] Fig. 1: Hafele, Keating & stewardess aboard airplane with two atomic clocks [Wiki HKE, 2014] Quantum OpticsandNanophotonicsAtomicClocks Peter Deiml

  4. Current time standard Definition of the second (1967) „The secondisthedurationof 9192631770 periodsoftheradiationcorrespondingtothetransitionbetweenthetwohyperfinelevelsofthegroundstateofthecaesium 133 atom“ [BIPD, 2006] • Why atomic properties? • Why the Cs-133 atom? • Why hyperfine levels? • Why exactly 9192631770 periods of the radiation? Fig. 3: Solar system with sun and the nine planets (not true to scale) [SeaSky, 2014] → value equals to ephimerises second Quantum Optics and Nanophotonics Atomic Clocks Peter Deiml

  5. Current time standard Why atomic properties? [Bauch, 2012] „ Zeit [ist] die Stellung des kleinen Zeigers meiner Uhr “ [Einstein, 1905] • Every frame of reference has its own time • Atomic properties determined by natural constants (in rest frame of the atom) Time determinedbynaturalconstants! Fig. 4: Spacetime in special relativity [Wiki SR, 2014] Quantum Optics and Nanophotonics Atomic Clocks Peter Deiml

  6. Current time standard Why the Cs-133 atom? [PTB] • Small thermal velocity due to large mass • (later: Doppler effect → 0) • Technology for measuring the resonance frequency was available in 1967 • The only natural isotope of caesium • Only two hyperfine levels in the ground state • Transition has small natural line width • Small boiling point (670°C) Quantum OpticsandNanophotonicsAtomicClocks Peter Deiml

  7. Current time standard Why hyperfine levels? [Audoin et al., 2005] Quantum number configuration of the outermost electron of Cs-133: • No fine structure (J) • Transition for time standard: F = 3 ↔ F = 4 Fig. 6: Cutting of the hyperfine structure of Cs-133 [Bauch, 2003] Quantum Optics and Nanophotonics Atomic Clocks Peter Deiml

  8. Spectroscopy General idea Investigation of the answer of atoms or molecules to a laserbeam Perfectmethodformeasurementofthesecond • Examples: • Information aboutstructureofstars Fig. 8: Dispersion of white light by a prism [Wiki SpC, 2014] Fig. 7: UVES on the very large telescope on Cerro Paranal (Chile) [Wiki SpC, 2014] • Scientific applications: medicine (MRT), chemistry, biology Quantum Optics and Nanophotonics Atomic Clocks Peter Deiml

  9. Spectroscopy Broadening mechanisms [Meschede, 2007] Natural line width: Fig. 9: spectrum of low-pressure mecury bulb [Wiki NLW, 2014] Doppler effect: Fig. 10: Gauß-Voigt profile with underlying natural line width [Meschede, 2007] Quantum Optics and Nanophotonics Atomic Clocks Peter Deiml 9

  10. Spectroscopy Broadening mechanisms [Meschede, 2007] Time-of-flight (TOF) broadening [Meschede, 2007] Fig. 11: Scheme of spectroscopy experiment [Wiki TOF, 2014] Other broadening mechanisms [Audoin et al., 2006] Quantum Optics and Nanophotonics Atomic Clocks Peter Deiml

  11. Ramsey-Spectroscopy Young‘s double slit (Position space): Fig. 12: Scheme of Young‘s double slit [Wiki YDS, 2014] Fig. 13: Distribution of intensity [Wiki YDS,2014] Quantum Optics and Nanophotonics Atomic Clocks Peter Deiml

  12. Ramsey-Spectroscopy Fig. 15: See frame 11 Fig. 14: Scheme of Ramsey-spectroscopy Quantum Optics and Nanophotonics Atomic Clocks Peter Deiml

  13. Caesium beam clock Caesium beam tube [Bauch, 2003],[Audoin et al., 2006] • Analyzer deflects F = 4 atoms towards detector Fig. 16: Scheme of the magnetically deflected caesium beam tube [Bauch, 2003] Quantum Optics and Nanophotonics Atomic Clocks Peter Deiml

  14. Caesium beam clock The CS2 clock at the Physikalisch Technische Bundesanstalt (PTB) Fig. 18: See frame 13 Fig. 17 : Vertical section of the vacuum chamber of PTB‘s primary clock CS2 [Bauch, 2003] Quantum Optics and Nanophotonics Atomic Clocks Peter Deiml

  15. Caesium beam clock Function of Polarizer/Analyzer [Audoin et al., 2006] Fig. 19: Energy of the hyperfine levels via the magentic flux density [Audoin et al., 2006] Quantum Optics and Nanophotonics Atomic Clocks Peter Deiml

  16. Caesium beam clock C field inside the cavity [Riehle, 2004] Fig. 20: See frame 12 Quantum Optics and Nanophotonics Atomic Clocks Peter Deiml

  17. Caesium beam clock Frequency response of a caesium beam tube [Audoin et al., 2006] Fig. 21: Scheme of the resonance of the central part [Bauch, 2003] Quantum OpticsandNanophotonicsAtomicClocks Peter Deiml

  18. Caesium beam clock Frequency response of a caesium beam tube [Audoin et al., 2006] Fig. 22: See frame 17 Quantum OpticsandNanophotonicsAtomicClocks Peter Deiml

  19. Laser cooling [Weyers et al., 1999] Fig. 23: Order of laser beams, their polarisation in an optical molasse [Weyers et al., 1999] Fig. 24: Order of laser beams, their polarisation in a magneto-optical trap [Weyers et al., 1999] Quantum Optics and Nanophotonics Atomic Clocks Peter Deiml

  20. Caesiumfountainclock General structure [Weyers et al., 1999] • Charge of magneto-optical trap • State-selection, Ramsey cavity and C-field analogeously to caesium beam clock • Difference: Preparation of F = 4 atoms • Only one interaction zone is needed • Different detection method with lasers Fig. 25: Simplified setup of the atomic fountain clock [Wynands et al., 2005] Quantum Optics and Nanophotonics Atomic Clocks Peter Deiml

  21. Caesiumfountainclocks Results of caesium fountain clock [Weyers et al., 1999] Figure 21 (CSF1): Fountainclocksmoreprecisethan beam clocks Quantum Optics and Nanophotonics Atomic Clocks Peter Deiml

  22. Outlook Optical clocks Fig. 27: Temporal development of frequency uncertainty [Udem et al.,2009] Optical clocksneedthefrequencycombtechnology Quantum Optics and Nanophotonics Atomic Clocks Peter Deiml

  23. Take-homemessage • Current time standard: • Exactdefinitionisneeded • Definition ofthesecond & itsjustification • Caesium beam/fountainclock: • General setup • Functionalprincipleandtaskof all components • Frequencyresponsesignal • Fountainclockmoreprecisethan beam clock • Spectroscopy: • Methodforrealizationof time standard • Broadeningmechanisms • Optical clocks: • More precisethancaesiumclocks • Frequencycombtechnologyisnessecary • Ramsey-Spectroscopy: • Double slit in time space • Strong analogytoYoung‘s double slit in positionspace Quantum Optics and Nanophotonics Atomic Clocks Peter Deiml

  24. Hallo Thank you for your attention and feel free to ask questions! (after the next presentation  ) Quantum Optics and Nanophotonics Atomic Clocks Peter Deiml

  25. Appendix Detectionandmeasurementoftransition [Weyers et al., 1999] • Measurement of flourescence by two detectors (photodiodes) Fig. 20: Scheme of the detection zone [Weyers et al., 1999] Quantum Optics and Nanophotonics Atomic Clocks Peter Deiml

  26. References [Audoin et al., 2006] Audoin C., Guinot B., The measurement of time, Cambridge University Press, 2001 [Bauch, 2003 ] Bauch A., Caesium Atomic Clocks: Function, Performance and Applications, Measurement Science and Technology 14, 1159-1173 (2003) [Bauch, 2012] Bauch A., Zeitmessung in der PTB, PTB Mitteilungen 122, 2012 [Bauch et al., 1998] Bauch A., Fischer B., Heindorff T., Schröder R., Performance of the PTB reconstructed primary clock CS1 and an estimate of ist current uncertainty, Metrologia 35, 829-845, 1998 [BIPD, 2006] Bureau international des poids et mesures, Organisation interfouvernementale de la Convention du Mètre. Le Système international d‘unités, 8e édtion, 2006 [Demtröder, 2005] Demtröder, W., Experimentalphysik 3, Atome, Moleküle und Festkörper, 3. Auflage, Springer Verlag, Berlin, Heidelberg, New York, 2005 [Einstein, 1905] Einstein A., Zur Elektrodynamik bewegter Körper, Annalen der Physik und Chemie. 17, S. 891 – 921, 1905 [Fließbach, 2006] Fließbach T., Allgemeine Relativitätstheorie, Spektrum, 2006 [Meschede, 2007] Meschede D., Optics, Light and Lasers, Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim, 2007 [PTB 1] Physikalisch-Technische Bundesanstalt, Wie funktioniert eine Atomuhr? [PTB 2] Physikalisch-Technische Bundesanstalt, Optische Atomuhren Quantum Optics and Nanophotonics Atomic Clocks Peter Deiml

  27. References [Riehle, 2004] Riehle F. Frequency Standards: Basics and Applications, Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim, 2006 [Udem et al., 2009] Udem T., Holzwarth R., Hänsch T. W., Femtosecond optical frequency combs, European Journal of Physics – Special Topis 172,69-79, 2009 [Weyers et al., 1999] Weyers S., Griebsch D., Hübner U., Schröder R., Tamm C., Bauch A., Die neue Caesiumfontäne der PTB, PTB-Mitteilungen 109, 483-491, 1999 [Wynands et al., 2005] Wynands R., Weyers S., Atomic fountain clocks, Metrologia 42, 64-79, 2005 Quantum Optics and Nanophotonics Atomic Clocks Peter Deiml

  28. Web references [Wiki SR, 2014] http://en.wikipedia.org/wiki/Special_relativity, 02.05.2014 [Wiki GPS, 2014] http://de.wikipedia.org/wiki/Global_Positioning_System, 02.05.2014 [Wiki SC, 2014] http://de.wikipedia.org/wiki/Bahnhofsuhr, 02.05.2014 [Wiki MBD, 2014] http://en.wikipedia.org/wiki/Maxwell%E2%80%93Boltzmann_distribution, 02.05.2014 [Wiki SpC, 2014] http://en.wikipedia.org/wiki/Spectroscopy, 02.05.2014 [Wiki NLW, 2014] http://de.wikipedia.org/wiki/Linienbreite, 02.05.2014 [Wiki TOF, 2014] http://de.wikipedia.org/wiki/Flugzeitverbreiterung, 02.05.2014 [Wiki YDS, 2014] http://de.wikipedia.org/wiki/Doppelspaltexperiment, 09.05.2014 [SeaSky, 2014] http://www.seasky.org/solar-system/solar-system.html, 18.05.2014 [Spiegel, 2013] http://www.spiegel.de/wissenschaft/technik/zeitmessung-physiker-bauen-zuverlaessigste-uhr-aller-zeiten-a-917409.html, 18.05.2014 Quantum Optics and Nanophotonics Atomic Clocks Peter Deiml

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