| Zugriffsnummer | 36148 |
| Dokumenttyp | Dissertation |
| Peer Review | unbekannt |
| Sprache | Englisch |
| Titel | Spectroscopic characterization of ion motion for an optical clock based on Coulomb crystals |
| Autor(in); Institution |
Keller, Jonas; QUEST Institute for Experimental Quantum Metrology, PTB-Braunschweig
|
| Quelle/Jahr | (2016), VI, 127 S. |
| Schriftenreihe | PTB-Bericht PTB-Opt-78 |
| Dissertationsvermerk | Dissertation, Universität Hannover, 2016 |
| ISBN | 978-3-95606-272-8 |
| Persistent Identifier | |
| Berichtsnummer | PTB-Opt-78 |
| Verlag | Bremen: Fachverl. NW in der Schünemann Verl. GmbH |
| Freie Schlagworte | optical clocks ; Coulomb crystals ; ultra-stabel lasers ; spectroscopy |
| Zusammenfassung | Laser-cooled, trapped ions are among the most successful candidates for an optical frequency standard, with fractional frequency uncertainties approaching the low 10-18 range. However, current implementations of optical ion clocks are based on a single reference ion, which results in an intrinsically low signal-to-noise ratio. Averaging times of several days are necessary for resolving the transition frequency well enough to benefit from these low systematic uncertainties. In order to overcome this impediment to applications, the averaging can be performed more quickly by interrogating an ensemble of ions simultaneously. Due to their mutual repulsion, these ions can be confined by a common trapping potential, in which they arrange in crystalline structures (Coulomb crystals). The technical challenge of this approach is to preserve the excellent systematic uncertainties obtainable with a single ion. This work contributes to the approach of using In / Yb Coulomb crystals as the reference for an optical clock. Two ultra-stable cavities for the stabilization of spectroscopy lasers have been set up. With a simple setup, a diode laser has been stabilized to σy(1 s) = 6 x 10-16. The vibration sensitivity of a simple 30 cm long spacer has been measured, showing that a cavity using this spacer can provide a fractional frequency instability of σy = 1 x 10-16 for times ) 30 ms, sufficient to operate a clock based on 100 In ions at its quantum projection noise limit of 7.2 x 10-17/√τ/s. Frequency shifts resulting from time dilation due to ion motion are among the limiting contributions in current ion frequency standards. A spectroscopy laser has been set up in order to characterize the motion of Coulomb crystals by interrogating a narrow transition in Yb. Spatially resolved state detection with an EMCCD camera allows multiple ions to be interrogated simultaneously. Groundstate cooling of two modes in a single ion allowed the determination of heating rates below 2 / s at secular frequencies around 500 kHz. Three micromotion compensation techniques have been characterized in terms of their resolution and applicability during clock operation. A new model was developed for the photon-correlation technique to allow quantitative evaluation in the common regime of comparable drive frequency and linewidth. It was experimentally verified in a comparison with resolved sideband measurements. Both the photon-correlation and the parametric excitation method were shown ca pable of micromotion compensation with a resulting fractional frequency uncertainty well below 10-19. Overall, it has been shown that the motional frequency shift contributions due to external heating, secular motion and micromotion in a single In ion can each be controlled at a level of 10-19 in the present setup and the foundation has been laid to extend these measurements to multiple ions. |
