1. Atomic Clocks Physical Seminar - Quantum Optics and Nanophotonics - Peter Deiml20.05.2014

2. Quantum Optics and Nanophotonics Atomic Clocks Peter Deiml2 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 Outlook: Optical Clock

3. 3Quantum Optics and Nanophotonics Atomic ClocksPeter Deiml Why do we need an exact definition of 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] Some scientific examples: Other SI-units (e.g. meter) based upon the second Spectrum of atoms (QM,QED) „Proof“ of equivalence principle, SR, GR (Hafele-Keating-/ Maryland-experiment) Gravitational waves Fine structure constant constant? Some everyday examples: Global Positioning System (GPS) Telecommunication Supply of energy Fig. 2: NAVSTAR satellite [Wiki GPS, 2014] Fig. 1: Hafele, Keating & stewardess aboard airplane with two atomic clocks [Wiki HKE, 2014]

4. 4 Definition of the second (1967) „The second is the duration of 9192631770 periods of the radiation corresponding to the transition between the two hyperfine levels of the ground state of the caesium 133 atom“ [BIPD, 2006] Quantum Optics and Nanophotonics Atomic ClocksPeter Deiml Why exactly 9192631770 periods of the radiation? Why atomic properties? Why the Cs-133 atom? Why hyperfine levels? Current time standard → value equals to ephimerises second Fig. 3: Solar system with sun and the nine planets (not true to scale ) [SeaSky, 2014]

5. Quantum Optics and Nanophotonics Atomic Clocks Peter Deiml5 Why atomic properties? [Bauch, 2012] Current time standard „ Zeit [ist] die Stellung des kleinen Zeigers meiner Uhr “ [Einstein, 1905] Fig. 4: Spacetime in special relativity [Wiki SR, 2014] Every frame of reference has its own time Time determined by natural constants! Atomic properties determined by natural constants (in rest frame of the atom)

6. Quantum Optics and Nanophotonics Atomic Clocks Peter Deiml6 Current time standard Why the Cs-133 atom? [PTB] Technology for measuring the resonance frequency was available in 1967 Small thermal velocity due to large mass (later: Doppler effect → 0) Only two hyperfine levels in the ground state The only natural isotope of caesium Small boiling point (670°C) Transition has small natural line width

7. Quantum Optics and Nanophotonics Atomic Clocks Peter Deiml7 Why hyperfine levels? [Audoin et al., 2005] Current time standard Quantum number configuration of the outermost electron of Cs-133: Fig. 6: Cutting of the hyperfine structure of Cs-133 [Bauch, 2003] No fine structure (J) Transition for time standard: F = 3 ↔ F = 4

8. Quantum Optics and Nanophotonics Atomic Clocks Peter Deiml8 Spectroscopy General idea Investigation of the answer of atoms or molecules to a laserbeam Examples: Information about structure of stars 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 Perfect method for measurement of the second

9. Quantum Optics and Nanophotonics Atomic Clocks Peter Deiml99 Doppler effect: Natural line width: Fig. 9: spectrum of low-pressure mecury bulb [Wiki NLW, 2014] Fig. 10: Gauß-Voigt profile with underlying natural line width [Meschede, 2007] Spectroscopy Broadening mechanisms [Meschede, 2007]

10. Quantum Optics and Nanophotonics Atomic Clocks Peter Deiml10 Spectroscopy Broadening mechanisms [Meschede, 2007] Fig. 11: Scheme of spectroscopy experiment [Wiki TOF, 2014] Other broadening mechanisms [Audoin et al., 2006] Time-of-flight (TOF) broadening [Meschede, 2007]

11. Quantum Optics and Nanophotonics Atomic Clocks Peter Deiml11 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]

12. Quantum Optics and Nanophotonics Atomic Clocks Peter Deiml12 Ramsey-Spectroscopy Fig. 14: Scheme of Ramsey-spectroscopy Fig. 15: See frame 11

13. Quantum Optics and Nanophotonics Atomic Clocks Peter Deiml13 Caesium beam clock Caesium beam tube [Bauch, 2003],[Audoin et al., 2006] Fig. 16: Scheme of the magnetically deflected caesium beam tube [Bauch, 2003] Analyzer deflects F = 4 atoms towards detector

14. Quantum Optics and Nanophotonics Atomic Clocks Peter Deiml14 Caesium beam clock The CS2 clock at the Physikalisch Technische Bundesanstalt (PTB) Fig. 17 : Vertical section of the vacuum chamber of PTB‘s primary clock CS2 [Bauch, 2003] Fig. 18: See frame 13

15. Quantum Optics and Nanophotonics Atomic Clocks Peter Deiml15 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]

16. Quantum Optics and Nanophotonics Atomic Clocks Peter Deiml16 Caesium beam clock C field inside the cavity [Riehle, 2004] Fig. 20: See frame 12

17. Quantum Optics and Nanophotonics Atomic Clocks Peter Deiml17 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]

18. Quantum Optics and Nanophotonics Atomic Clocks Peter Deiml18 Caesium beam clock Frequency response of a caesium beam tube [Audoin et al., 2006] Fig. 22: See frame 17

19. Quantum Optics and Nanophotonics Atomic Clocks Peter Deiml19 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]

20. Quantum Optics and Nanophotonics Atomic Clocks Peter Deiml20 Caesium fountain clock General structure [Weyers et al., 1999] Fig. 25: Simplified setup of the atomic fountain clock [Wynands et al., 2005] Only one interaction zone is needed State-selection, Ramsey cavity and C-field analogeously to caesium beam clock Different detection method with lasers Difference: Preparation of F = 4 atoms Charge of magneto-optical trap

21. Quantum Optics and Nanophotonics Atomic Clocks Peter Deiml21 Caesium fountain clocks Results of caesium fountain clock [Weyers et al., 1999] Fountain clocks more precise than beam clocks Figure 21 (CSF1):

22. Quantum Optics and Nanophotonics Atomic Clocks Peter Deiml22 Outlook Optical clocks Fig. 27: Temporal development of frequency uncertainty [Udem et al.,2009] Optical clocks need the frequency comb technology

23. Quantum Optics and Nanophotonics Atomic Clocks Peter Deiml23 Take-home message Current time standard: Exact definition is needed Definition of the second & its justification Spectroscopy: Method for realization of time standard Broadening mechanisms Caesium beam/fountain clock: General setup Functional principle and task of all components Frequency response signal Fountain clock more precise than beam clock Optical clocks: More precise than caesium clocks Frequency comb technology is nessecary Ramsey-Spectroscopy: Double slit in time space Strong analogy to Young‘s double slit in position space

24. Quantum Optics and Nanophotonics Atomic Clocks Peter Deiml24 Thank you for your attention and feel free to ask questions! (after the next presentation ) Hallo

25. Quantum Optics and Nanophotonics Atomic Clocks Peter Deiml25 Appendix Detection and measurement of transition [Weyers et al., 1999] Fig. 20: Scheme of the detection zone [Weyers et al., 1999] Measurement of flourescence by two detectors (photodiodes)

26. Quantum Optics and Nanophotonics Atomic Clocks Peter Deiml26 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

27. Quantum Optics and Nanophotonics Atomic Clocks Peter Deiml27 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

28. Quantum Optics and Nanophotonics Atomic Clocks Peter Deiml28 Web references [Wiki SR, 2014]http://en.wikipedia.org/wiki/Special_relativity, 02.05.2014http://en.wikipedia.org/wiki/Special_relativity [Wiki GPS, 2014]http://de.wikipedia.org/wiki/Global_Positioning_System, 02.05.2014http://de.wikipedia.org/wiki/Global_Positioning_System [Wiki SC, 2014]http://de.wikipedia.org/wiki/Bahnhofsuhr, 02.05.2014http://de.wikipedia.org/wiki/Bahnhofsuhr [Wiki MBD, 2014]http://en.wikipedia.org/wiki/Maxwell%E2%80%93Boltzmann_distribution, 02.05.2014http://en.wikipedia.org/wiki/Maxwell%E2%80%93Boltzmann_distribution [Wiki SpC, 2014]http://en.wikipedia.org/wiki/Spectroscopy, 02.05.2014http://en.wikipedia.org/wiki/Spectroscopy [Wiki NLW, 2014]http://de.wikipedia.org/wiki/Linienbreite, 02.05.2014http://de.wikipedia.org/wiki/Linienbreite [Wiki TOF, 2014]http://de.wikipedia.org/wiki/Flugzeitverbreiterung, 02.05.2014http://de.wikipedia.org/wiki/Flugzeitverbreiterung [Wiki YDS, 2014]http://de.wikipedia.org/wiki/Doppelspaltexperiment, 09.05.2014http://de.wikipedia.org/wiki/Doppelspaltexperiment [SeaSky, 2014]http://www.seasky.org/solar-system/solar-system.html, 18.05.2014http://www.seasky.org/solar-system/solar-system.html [Spiegel, 2013]http://www.spiegel.de/wissenschaft/technik/zeitmessung-physiker-bauen-zuverlaessigste-uhr- aller-zeiten-a-917409.html, 18.05.2014http://www.spiegel.de/wissenschaft/technik/zeitmessung-physiker-bauen-zuverlaessigste-uhr- aller-zeiten-a-917409.html