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% Creation date: 2023-06-06
% Creation time: 12-28-40
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@Article { FalkeSWMVWLGRSL2011,
   title = {The 87-Sr optical frequency standard at PTB},
   journal = {Metrologia},
   year = {2011},
   volume = {48},
   pages = {399-407},
   author = {Falke, St. and Schnatz, H. and Winfried, J. S. R. V. and Middelmann, Th. and Vogt, St. and Weyers, S. and Lipphardt, B. and Grosche, G. and Riehle, F. and Sterr, U. and Lisdat, Ch.}
}

@Article { Riehle2010,
   title = {Hyper-Ramsey spectroscopy of optical clock transitions},
   journal = {Physical Review A (2010)},
   year = {2010},
   abstract = {We present nonstandard optical Ramsey schemes that use pulses individually tailored in duration, phase, and frequency to cancel spurious frequency shifts related to the excitation itself. In particular, the field shifts and their uncertainties can be radically suppressed (by two to four orders of magnitude) in comparison with the usual Ramsey method (using two equal pulses) as well as with single-pulse Rabi spectroscopy. Atom interferometers and optical clocks based on two-photon transitions, heavily forbidden transitions, ormagnetically induced spectroscopy could significantly benefit from this method. In the latter case, these frequency shifts can be suppressed considerably below a fractional level of 10\(^{-17}\). Moreover, our approach opens the door for high-precision optical clocks based on direct frequency comb spectroscopy.},
   publisher = {Melville, NY: AIP},
   language = {Englisch},
   ISSN = {ISSN 1050-2947 (print) ; ISSN 1094-1622 (online)},
   DOI = {10.1103/PhysRevA.82.011804},
   in_library = {1},
   author = {Yudin, V. I. and Taichenachev, A. V. and Oates, C. W. and Barber, Z. W. and Lemke, N. D. and Ludlow, A. D and Sterr, Uwe and Lisdat, Christian and Riehle, Fritz}
}

@Article { TaichenachevYOBLLSLR2009,
   title = {Compensation of field-induced frequency shifts in Ramsey spectroscopy of optical clock transitions},
   journal = {JETP Letters (2009)},
   year = {2009},
   volume = {90},
   number = {11},
   pages = {713 - 717},
   abstract = {We have extended Ramsey spectroscopy by stepping the probe frequency during the two Ramsey excitation pulses to compensate frequency shifts induced by the excitation itself. This makes precision Ramsey spectroscopy applicable even for transitions that have Stark and Zeeman shifts comparable to the spectroscopic resolution. The method enables a new way to evaluate and compensate key frequency shifts, which benefits in particular, optical clocks based on magnetic field-induced, spectroscopy, two-photon transitions, or heavily forbidden transitions.},
   publisher = {Road Town, Tortola: Pleiades Publ.},
   language = {English},
   ISSN = {ISSN 0021-3640},
   DOI = {10.1134/S0021364009230052},
   author = {Taichenachev, A. V. and Yudin, V. I. and Oates, C. W. and Barber, Z. W. and Lemke, N. D. and Ludlow, A. D. and Sterr, Uwe and Lisdat, Christian and Riehle, Fritz}
}

@Article { LisdatVMRS2009,
   title = {Collisional losses, decoherence, and frequency shifts in optical lattice clocks with bosons},
   journal = {Physical Review Letters (2009)},
   year = {2009},
   volume = {103},
   number = {9},
   pages = {090801-1 - 090801-4},
   abstract = {We have quantified collisional losses, decoherence and the collision shift in a one-dimensional optical lattice clock on the highly forbidden transition \(^{1}\)S\(_{0}\)-\(^{3}\)P\(_{0}\) at 698 nm with bosonic \(^{88}\)Sr. We were able to distinguish two loss channels: inelastic collisions between atoms in the upper and lower clock state and atoms in the upper clock state only. Based on the measured coefficients, we determine the operation parameters at which a 1D-lattice clock with \(^{88}\)Sr shows no degradation due to collisions on the fractional uncertainty level of 10\(^{-16}\).},
   publisher = {Ridge, NY: APS},
   language = {English},
   ISSN = {SN 0031-9007},
   DOI = {10.1103/PhysRevLett.103.090801},
   author = {Lisdat, Christian and Vellore, Winfred and Middelmann, Thomas and Riehle, Fritz and Sterr, Uwe}
}

@Article { KraftVARS2009,
   title = {Bose-Einstein condensation of alkaline earth atoms: \(^{40}\)Ca},
   journal = {Physical Review Letters  (2009)},
   year = {2009},
   volume = {103},
   number = {13},
   pages = {130401-1 - 130401-4},
   abstract = {We have achieved Bose-Einstein condensation of \(^{40}\)Ca, the first for an alkaline earth element. The influence of elastic and inelastic collisions associated with the large ground-state s-wave scattering length of \(^{40}\)Ca was measured. From these findings, an optimized loading and cooling scheme was developed that allowed us to condense about 2{\~A}—10\(^{4}\) atoms after laser cooling in a two-stage magneto-optical trap and subsequent forced evaporation in a crossed dipole trap within less than 3 s. The condensation of an alkaline earth element opens novel opportunities \(^{1}\)\emph{S}-\(^{3}\)\emph{P} asymptotes.},
   publisher = {Ridge, NY: APS},
   language = {English},
   ISSN = {ISSN 0031-9007},
   DOI = {10.1103/PhysRevLett.103.130401},
   author = {Kraft, Sebastian and Vogt, Felix and Appel, Oliver and Riehle, Fritz and Sterr, Uwe}
}

@Article { NazarovaLRS2008,
   title = {A low frequency-noise diode laser for atom interferometry},
   journal = {Journal of the Optical Society of America B (2008)},
   year = {2008},
   volume = {25},
   number = {10},
   pages = {1632 - 1638},
   abstract = {We investigate the influence of fast frequency fluctuations of the interrogation laser on the obtainable signal-to-noise ratio in Ramsey-Bord{\~A}© atom interferometers. It is shown that the excessive high frequency noise of diode lasers can degrade significantly the signal-to-noise ratio in an atom interferometer. To overcome these limitations, we have devised a low-noise light source by frequency-filtering a diode laser in a high finesse cavity and further amplifying the transmitted power by injection-locking a solitary laser diode. When this laser source was used for atom interferometry with laser cooled calcium atoms, the signal-to-noise ratio could be further improved by a factor of 3.5 compared to the use of the unfiltered 1-Hz-linewidth laser source.},
   publisher = {Washington, DC: OSA},
   language = {English},
   ISSN = {ISSN 0740-3224},
   DOI = {10.1364/JOSAB.25.001632},
   author = {Nazarova, Tatiana and Lisdat, Christian and Riehle, Fritz and Sterr, Uwe}
}

@Article { SchillerGNKWGKMMSRPTERKSTLHH2007,
   title = {Optical clocks in space},
   journal = {Nucl. Phys. B (Proc. Suppl.)},
   year = {2007},
   volume = {166},
   number = {300},
   pages = {arXiv: gr-qc/0608081},
   author = {Schiller, S. and G{\~A}¶rlitz, A. and Nevsky, A. and Koelemeij, J.C.J. and Wicht, A. and Gill, P. and Klein, H.A. and Margolis, H.S. and Mileti, G. and Sterr, U. and Riehle, F. and Peik, E. and Tamm, Chr. and Ertmer, W. and Rasel, E. and Klein, V. and Salomon, C. and Tino, G.M. and Lemonde, P. and Holzwarth, R. and H{\~A}¤nsch, T.W.}
}

@Article { VogtGNSRLT2010,
   title = {Determination of the calcium ground state scattering length by photoassociation spectroscopy at large detunings},
   journal = {European Physical Journal D (2007)},
   year = {2007},
   volume = {44},
   pages = {73 - 79},
   abstract = {Photoassociation spectroscopy was used to determine the s-wave scattering of \(^{40}\)Ca atoms in their electronic ground state. Vibrational levels were observed in an extended range of up to 182 GHz below the dissociation limit 4s\(^{2 1}\)S\(_{0}\)-4s4p \(^{1}\)P\(_{1}\). Thus, the frequency interval was nearly tripled, in which photoassociation was observed compared to previous measurements. The spectra were analyzed by means of quantum mechanical simulations.},
   publisher = {Orsay [u.a.]: EDP Sciences [u.a.]},
   language = {English},
   ISSN = {ISSN 1434-6060},
   DOI = {10.1140/epjd/e2007-00175-8},
   author = {Vogt, Felix and Grain, Christophe and Nazarova, Tatiana and Sterr, Uwe and Riehle, Fritz and Lisdat, Christian and Tiemann, E.}
}

@Article { GrainNDVLTSR2007,
   title = {Feasibility of narrow-line cooling in optical dipole traps},
   journal = {European Physical Journal D (2007)},
   year = {2007},
   abstract = {We have investigated the influence of narrow-line laser cooling on the loading of Ca atoms into optical dipole traps. To describe the narrow-line cooling of alkaline-earth atoms in combination with optical dipole trapping, we have developed a model that takes into account the light shifts of the cooling transition in three dimensions. The model is compared with two experimental realizations of optical dipole traps for calcium at the wavelengths 514 nm and 10.6 ?m.},
   publisher = {Heidelberg [u.a.]: Springer},
   language = {English},
   ISSN = {ISSN 1434-6060},
   DOI = {10.1140/epjd/e2007-00052-6},
   author = {Grain, Christophe and Nazarova, Tatiana and Degenhardt, Carsten and Vogt, Felix and Lisdat, Christian and Tiemann, E. and Sterr, Uwe and Riehle, Fritz}
}

@Article { NazarovaRS2006,
   title = {Vibration-insensitive reference cavity for an ultra-narrow linewidth laser},
   journal = {Appl. Phys. B},
   year = {2006},
   volume = {83},
   pages = {531?536},
   author = {Nazarova, T. and Riehle, F. and Sterr, U.}
}

@Article { NazarovaRS2006,
   title = {Vibration-insensitive reference cavity for an ultra-narrowlinewidth laser},
   journal = {Applied Physics B (2006)},
   year = {2006},
   volume = {84},
   number = {4},
   pages = {531 - 536},
   abstract = {We report a novel mounting of the reference cavity used for stabilization of the clock laser in an optical frequency standard. The cavity axis is oriented horizontally and the cavity is supported in its horizontal symmetry plane on four support points. The positions of the points were optimized by finite element analysis. A sensitivity to accelerations of 1.5 kHz/(m/s{\^A}²) in the vertical and 14 kHz/(m/s{\^A}²) in the horizontal direction was measured, which is a reduction in the vertical sensitivity by two orders of magnitude compared to the usual support from below.},
   publisher = {Berlin [u.a.]: Springer},
   language = {English},
   ISSN = {ISSN 0946-2171 (print) ; ISSN 1432-0649 (online)},
   DOI = {10.1007/s00340-006-2225-y},
   author = {Nazarova, Tatiana and Riehle, Fritz and Sterr, Uwe}
}

@Article { DegenhardtSLWSLNPSHR2005,
   title = {Calcium optical frequency standard with ultracold atoms: approaching 10\(^{-15}\) relative uncertainty},
   journal = {Physical Review A (2005)},
   year = {2005},
   volume = {72},
   pages = {062111-1 - 062111-17},
   abstract = {An optical frequency standard based on an ensemble of neutral calcium atoms laser-cooled to 12 ?K has been realized. By using ultracold atoms, one major previous source of uncertainty, the residual Doppler effect, was reduced. We show that cold collisions contribute a negligible amount to the uncertainty. The influence of a temporal evolution of the phase of the laser pulses used to interrogate the clock transition was measured and corrected for. The frequency of the clock transition at 657 nm was referenced to the caesium fountain clock of PTB utilizing a femtosecond comb generator with a fractional uncertainty of 1.2 x 10\(^{-14}\). The transition frequency was determined to be (455 986 240 494 144 {\^A}± 5.3) Hz, making the calcium clock transition one of the most accurately known optical transitions. A frequency stability of 3 x 10\(^{-15}\) at 100 s averaging time was achieved and the noise contributions that limit to the observed stability were analyzed in detail. Additionally, the natural linewidth of the clock transition has been determined.},
   publisher = {Melville, NY: AIP},
   language = {English},
   ISSN = {ISSN 1050-2947},
   DOI = {10.1103/PhysRevA.72.062111},
   author = {Degenhardt, Carsten and Stoehr, Hardo and Lisdat, Christian and Wilpers, Guido and Schnatz, Harald and Lipphardt, Burghard and Nazarova, Tatiana and Pottie, Paul-Eric and Sterr, Uwe and Helmcke, J{\~A}¼rgen and Riehle, Fritz}
}

@Article { WilpersBDSHR2002,
   title = {Optical Clock with Ultracold Neutral Atoms},
   journal = {Phys. Rev. Lett. (2002)},
   year = {2002},
   volume = {89},
   number = {23},
   pages = {230801-1 - 230801-4},
   abstract = {We demonstrate how to realize an optical clock with neutral atoms that is competitive to the currently best single ion optical clocks in accuracy and superior in stability. Using ultracold atoms in a Ca optical frequency standard, we show how to reduce the relative uncertainty to below \(^{10-15}\). We observed atom interferences for stabilization of the laser to the clock transition with a visibility of 0.36, which is 70\% of the ultimate limit achievable with atoms at rest. A novel scheme was applied to detect these atom interferences with the prospect to reach the quantum projection noise limit at an exceptional low instability of 4{\~A}—10\(^{-17}\) in 1{\^A} s},
   url = {http://link.aps.org/doi/10.1103/PhysRevLett.89.230801},
   publisher = {Ridge, NY: American Physical Society},
   language = {English},
   ISSN = {ISSN 0031-9007},
   DOI = {10.1103/PhysRevLett.89.230801},
   in_library = {1},
   author = {Wilpers, Guido and Binnewies, Tomas and Degenhardt, Carsten and Sterr, Uwe and Helmcke, J{\~A}¼rgen and Riehle, Fritz}
}

@Article { BinnewiesWSRHMRE2001,
   title = {Doppler cooling and trapping on forbidden transitions},
   journal = {Physical Review Letters (2001)},
   year = {2001},
   volume = {87},
   number = {12},
   pages = {123002-1 - 123002-4},
   abstract = {Ultracold atoms at temperature close to the recoil limit have been achieved by extending Doppler cooling to forbidden transitions. A cloud of \(^{40}\)Ca atoms has been cooled and trapped to a temperature as low as 6 ?K by operating a magneto-optical trap on the spin-forbidden intercombination transition. Quenching the long-lived excited state with an additional laser enhanced the scattering rate by a factor of 15, while a high selectivity in velocity was preserved. With this method more than 10 \% of pre-cooled atoms from a standard magneto-optical trap have been transferred to the ultracoled trap. Monte-Carlo simulations of the cooling process are in good agreement with the experiments.},
   keywords = {laser cooling
atom interferometry
ultracold atoms},
   language = {English},
   ISSN = {ISSN 0031-9007},
   DOI = {10.1103/PhysRevLett.87.123002},
   author = {Binnewies, Tomas and Wilpers, Guido and Sterr, Uwe and Riehle, Fritz and Helmcke, J{\~A}¼rgen and Mehlst{\~A}¤ubler, T. E. and Rasel, E. M. and Ertmer, W.}
}