Podcasts about 1s 2s

After interviewing several Washington Spirit players and hearing from multiple that Dorian Bailey controls the music for the team, we had to know more. So Annie & André conducted a special Hey Spirits investigation and went straight to the source: DJ Dor herself! DJ tells us all about her process, how she reads the reactions to what she plays, how she sources new music, what she likes to listen to, and was gracious enough to drop a gameday playlist for Spirit supporters! Please listen, subscribe, rate and review! ==================== Follow Us Twitter: ⁠⁠⁠⁠⁠⁠⁠⁠⁠⁠⁠⁠⁠⁠⁠⁠⁠⁠⁠⁠⁠⁠⁠⁠⁠⁠⁠⁠⁠⁠⁠@HeySpirits⁠⁠⁠⁠⁠⁠⁠⁠⁠⁠⁠⁠⁠⁠⁠⁠⁠⁠⁠⁠⁠⁠⁠⁠⁠⁠⁠ ==================== Track: Fungible — Hiracutch [Audio Library Release] Music provided by Audio Library Plus Watch: https://youtu.be/ILkTHxSNenI Free Download / Stream: https://alplus.io/after-rain

We get right after it in our 70th edition of the pod talking about Conference Final series getting underway in the 2022 Stanley Cup Playoffs! Eastern Conference Final (:30) - Tampa Bay Lightning vs New York Rangers: With chants of “Igor's better” echoing throughout MSG, Igor Shesterkin and the “Kid Line” of Filip Chytil, Alexis Lafrenière and Kaapo Kakko helped the Rangers grab a 1-0 series lead in the ECF after a 6-2 win Wednesday.The pace in game 1 (4:18)Shesterkin style/sense (10:00)Our Sports Interaction (12:27) features our inside look at both game 2s in the Conference Finals!Western Conference Final (14:55) - Edmonton Oilers vs Colorado Avalanche: After THE second-highest scoring game in Conference Finals history (tied), the Avs and Oilers play Game 2 of the West Final at Ball Arena Thursday! We talk some more goaltending, confidence in the playoffs and the special play from Igor Shesterkin(27:40).We also hit on some NHL News and Notes and talk about the headline out of Montreal this week with Martin St. Louis staying behind the Habs bench (30:57).And in our Ultimate Hockey Fans Final Thoughts (34:37) Button gets into the NHL coaching carousel over the next month and Kool talks about the Philadelphia Flyers vacancy and the perfect John Tortorella fit!

Individually they were just like those guys who like to hang around the comic book shop and talk comics but together they form EMX! In this eXplicit, uncut, unedited and DOUBLE SIZED Hellfire Gala episode of EMX we review Marvel Comics X-Men books of June 2021.   Marauders (2019) #21 X-Force (2019) #20 Hellions (2020) #12 Excalibur (2019) #21 X-Men (2019) #21 Children of the Atom (2021) #4 Planet-Sized X-Men (2021) #1 New Mutants (2019) #19 X-Corp (2021) #2 Wolverine (2020) #13 S.W.O.R.D. (2021) 6 Way of X (2021) #3 X-Factor (2020) #10 Cable (2020) #11 [RSS] Subscribe [RSS] EMX Subscribe [iTunes] Subscribe [Google Play] Subscribe All Podcasts  Email: EMP@EarthsMightiestPodcast.com Website: http://www.EarthsMightiestPodcast.comFacebook Group: http://facebookgroup.earthsmightiestpodcast.com/Viet's Website: http://www.comedianviet.comThacher's Website: http://www.DemonWeasel.com  

This week's special guest is VJ Aazera, we discuss how they became a VJ, Conventions & cover some harder topics on race and social equality. We hope you listen and enjoy. Join the conversation! Instagram: @gayspacepod Email: gayspacepod@gmail.com Merch: gayspacepod.threadless.com --- Support this podcast: https://anchor.fm/gay-space/support

Life Hacks Week 03: 1s, 2s, 3s Prioritize by www.uptownchurch.mn

This is a trial episode! MHs Boosie is learning to edit with Quaymo! Be sure to book Queen Quaymo for podcast training Courses and start your own podcast today!!(more information on her website: www.queenquaymo.com) on this Episode we discuss internet trolling, red flags we ignore when dating, and being discouraged while dating. --- This episode is sponsored by · Anchor: The easiest way to make a podcast. https://anchor.fm/app

V prvom tohtoročnom podcaste si povieme o podmienkach, ktoré si kladie vydavateľ vedeckých časopisov Elsevier a že v niektorých krajinách to už vedeckú verejnosť prestáva pomaličky baviť. Hovoriť budeme i o veľkom úspechu štúdie vakcíny proti ebole. TémyZdroje Intro Vydavateľ vedeckých časopisov Elsevier Vakcína proti ebole Fakt a fikcia Outro Scientists in Germany, Peru and Taiwan to lose access to Elsevier journals It's official: We finally have an Ebola vaccine that's up to 100% effective About Ebola Virus Disease Final trial results confirm Ebola vaccine provides high protection against disease Observation of the 1S–2S transition in trapped antihydrogen Dark matter component decaying after recombination: Lensing constraints with Planck data Image taken by Mastcam: Left (MAST_LEFT) onboard NASA's Mars rover Curiosity on Sol 1294

With residual uncertainties at the 10^-18 level, modern atomic frequency standards constitute extremely precise measurement devices. Besides frequency and time metrology, they provide valuable tools to investigate the validity of Einstein's theory of general relativity, to test a possible time variation of the fundamental constants, and to verify predictions of quantum electrodynamics. Furthermore, applications as diverse as geodesy, satellite navigation, and very long base-line interferometry may benefit from steadily improving precision of both microwave and optical atomic clocks. Clocks ticking at optical frequencies slice time into much finer intervals than microwave clocks and thus provide increased stability. It is expected that this will result in a redefinition of the second in the International System of Units (SI). However, any frequency measurement is based on a comparison to a second, ideally more precise frequency. A single clock, as highly developed as it may be, is useless if it is not accessible for applications. Unfortunately, the most precise optical clocks or frequency standards can not be readily transported. Hence, in order to link the increasing number of world-wide precision laboratories engaged in state-of-the-art optical frequency standards, a suitable infrastructure is of crucial importance. Today, the stabilities of current satellite based dissemination techniques using global satellite navigation systems (such as GPS, GLONASS) or two way satellite time and frequency transfer reach an uncertainty level of 10^-15 after one day of comparison . While this is sufficient for the comparison of most microwave clock systems, the exploitation of the full potential of optical clocks requires more advanced techniques. This work demonstrates that the transmission of an optical carrier phase via telecommunication fiber links can provide a highly accurate means for clock comparisons reaching continental scales: Two 920 km long fibers are used to connect MPQ (Max-Planck- Institut für Quantenoptik, Garching, Germany) and PTB (Physikalisch-Technische Bundesanstalt, Braunschweig, Germany) separated by a geographical distance of 600 km. The fibers run in a cable duct next to a gas pipeline and are actively compensated for fluctuations of their optical path length that lead to frequency offsets via the Doppler effect. Together with specially designed and remotely controllable in-line amplication this enables the transfer of an ultra-stable optical signal across a large part of Germany with a stability of 5 x 10^-15 after one second, reaching 10^-18 after less than 1000 seconds of integration time. Any frequency deviation induced by the transmission can be constrained to be smaller than 4 x 10^-19. As a first application, the fiber link was used to measure the 1S-2S two photon transition frequency in atomic hydrogen at MPQ referenced to PTB's primary Cs-fountain clock (CSF1). Hydrogen allows for precise theoretical analysis and the named transition possesses a narrow natural line width of 1.3 Hz. Hence, this experiment constitutes a very accurate test bed for quantum electrodynamics and has been performed at MPQ with ever increasing accuracy. The latest measurement has reached a level of precision at which satellite-based referencing to a remote primary clock is limiting the experiment. Using the fiber link, a frequency measurement can be carried out directly since the transmission via the optical carrier phase provides orders of magnitude better stability than state-of-the-art microwave clocks. The achieved results demonstrate that high-precision optical frequency dissemination via optical fibers can be employed in real world applications. Embedded in an existing telecommunication network and passing several urban agglomerations the fiber link now permanently connects MPQ and PTB and is operated routinely. It represents far more than a proof-of-principle experiment conducted under optimized laboratory conditions. Rather it constitutes a solution for the topical issue of remote optical clock comparison. This opens a variety of applications in fundamental physics such as tests of general and special relativity as well as quantum electrodynamics. Beyond that, such a link will enable clock-based, relativistic geodesy at the sub-decimeter level. Further applications in navigation, geology, dynamic ocean topography and seismology are currently being discussed. In the future, this link will serve as a backbone of a Europe-wide optical frequency dissemination network.

The investigation of laser-matter interactions calls for ever shorter pulses as new effects can thus be explored. With laser pulses consisting of only a few cycles of the electric field, the phase of these electric field oscillations becomes important for many applications. In this thesis ultrafast laser sources are presented that provide few-cycle laser pulses with controlled evolution of the electric field waveform. Firstly, a technique for phasestabilizing ultra-broadband oscillators is discussed. With a simple setup it improves the reproducibility of the phase by an order of magnitude compared to previously existing methods. In a further step, such a phase-stabilized oscillator was integrated into a chirped-pulse amplifier. The preservation of phase-stability during amplification is ensured by secondary phase detection. The phase-stabilized intense laser pulses from this system were employed in a series of experiments that studied strong-field phenomena in a time-resolved manner. For instance, the laser-induced tunneling of electrons from atoms was studied on a sub-femtosecond timescale. Additional evidence for the reproducibility of the electric field waveform of the laser pulses is presented here: individual signatures of the electric field half-cycles were found in photoelectron spectra from above-threshold ionization. Frequency conversion of intense laser pulses by high-order harmonic generation is a common way of producing coherent light in the extreme ultraviolet (XUV) spectral region. Many attempts have been made to increase the low efficiency of this nonlinear process, e.g. by quasi phase-matching. Here, high-harmonic generation from solid surfaces under grazing incidence instead from a gas target is studied as higher efficiencies are expected in this configuration. Another approach to increasing the efficiency of high-harmonic generation is the placing of the gas target in an enhancement resonator. Additionally, the production of XUV photons happens at the full repetition rate of the seeding laser, i.e. in the region of several tens to hundreds of megahertz. This high repetition rate enables the use of the XUV light for high-precision optical frequency metrology with the frequency comb technique. With such an arrangement, harmonics up to 15th order were produced. A build-up cavity that stacks femtosecond laser pulses in a coherent manner to produce intra-cavity pulse energies of more than ten microjoules at a repetition rate of ten megahertz is presented here. With this high average power measuring hitherto uninvestigated optical transition frequencies in the XUV, such as the 1S-2S transition in singly charged helium ions may become a reality.

In the course of this work, a system was designed and developed to nonlinearily convert a femtosecond frequency comb laser into the extreme ultraviolet (XUV) spectral range (120-30 nm). The optical frequency comb, for which the nobel prize 2005 was awarded to John Hall and Theodor W. Hänsch, has become an indispensable tool for high precision spectroscopy. With the aid of a mode locked femtosecond laser it is possible to directly and phase coherently link the radio frequency domain and the frequency range of visible light. Today's most accurate time standard, the cesium atomic clock operates in the former and therefore it became possible for the first time to compare arbitrary optical frequencies with our primary time standard and measure them with 15 digits of accuracy. Among other things, this method allowed one of the most accurate test of quantum electrodynamics (QED) today in the course of the determination of the 1S-2S transition frequency of atomic hydrogen that is carried out in one of our labs. But also experiments in the field of ultrafast physics rely on the frequency comb technique to generate precisely controlled optical waveforms. An especially intriguing possibility is to exploit the unique combination of high peak power in the megawatt range and the high spectral quality (on the order of 10^14) of single comb modes of a femtosecond frequency comb. To this end, in the method presented in this thesis, the femtosecond pulse train is coupled to an optical resonator of high finesse. With this trick, the field strength inside the resonator exceeds the driving lasers field by almost an order of magnitude. Enough to efficiently drive a nonlinear process of high order inside a medium of xenon atoms. As a result harmonics of the driving frequency comb up to 15nth order are generated. The obtained field contains photons with energies exceeding 20~eV, a spectral region which is not or only hard to access by conventional continuous laser source. Therefore the presented XUV frequency comb source brings direct frequency measurements at such high photon energies into the realm of possibility for the first time. In particular, an improved version of the demonstrated source will be used to take the next step in an experiment with a long tradition in our group, the 1S-2S spectroscopy of atomic hydrogen. The generated frequency comb in the vicinity of 60~nm wave length will be used to probe the 1S-2S transition in singly charged helium, a hydrogen like system with larger nuclear charge. From such a measurement it can be expected that, compared to hydrogen, relativistic corrections from the QED theory become more important as the system has higher energies in general. For this reason this could lead to a test of QED with increased sensitivity. Other applications of such a compact and relatively simple coherent source of XUV radiation could be high resolution spectroscopy, XUV holography, but could also lie in the research area of ultrafast physics.

In dieser Arbeit wurde die Femtosekunden (fs)-Frequenzkammtechnik, die in der Arbeitsgruppe von Prof. T. W. Hänsch entwickelt wurde, angewendet, um die Genauigkeit nichtlinearer Prozesse zu überprüfen und eine mögliche zeitliche Veränderung von Naturkonstanten nachzuweisen. Ein Frequenzkamm ist das Spektrum eines regelmäßigen kohärenten Pulszugs, der von einem modengekoppelten Laser ausgesendet wird. Die Frequenzen f_n der Kammoden sind durch f_n=f_ce+n*f_r gegeben. Dabei ist n eine natürliche Zahl der Größenordnung 10^6, f_r die Pulswiederholrate des Lasers und f_ce eine für alle Moden gleiche Frequenzverschiebung. Wird das Spektrum eines fs-Lasers mit Hilfe einer mikrostrukturierten Glasfaser auf eine Oktave verbreitert, so können die beiden Radiofrequenzen f_r und f_ce auf einfache Weise gemessen und kontrolliert werden. Einen fs-Frequenzkamm kann man sich dabei anschaulich als Getriebe vorstellen, der optische Frequenzen und Radiofrequenzen phasengenau miteinander verbindet. Das oktavenbreite Spektrum nach einer mikrostrukturierten Glasfaser wurde in dieser Arbeit dazu verwendet, um in einem nichtlinearen Kristall durch Summenfrequenzmischung (SFG) bzw. Differenzfrequenzmischung (DFG) zwei neue Frequenzkämme zu erzeugen, deren Frequenzverschiebung 2*f_ce (SFG) bzw. f_ce=0 (DFG) beträgt. Durch das Verschwinden von f_ce eignet sich der DFG-Kamm als stabiles Uhrwerk für zukünftige optische Uhren, von denen eine relative Genauigkeit von 10^(-18) erwartet wird, was etwa 1000 mal genauer ist als die besten Cs-Atomuhren der Welt. Ein Vergleich des erzeugten SFG- und DFG-Kamms mit dem Originalkamm gestattet darüber hinaus die Überprüfung der Genauigkeit nichtlinearer Prozesse mit einer relativen Genauigkeit von 6,6*10^(-21), was verglichen mit früheren Arbeiten eine 100 fache Verbesserung darstellt. Eine Abweichung von den erwarteten Werten konnte im Rahmen der Meßgenauigkeit nicht beobachtet werden. In Zusammenarbeit mit dem Wasserstofflabor in unserer Arbeitsgruppe wurde die Frequenz des 1S-2S Übergangs in atomarem Wasserstoff zu 2466061413187087+-34 Hz gemessen, was einer relativen Genauigkeit von 1,4*10^(-14) entspricht. Damit gehört die 1S-2S Frequenz zu den am besten bekannten optischen Frequenzen. Für ihre Messung wurde ein fs-Frequenzkammgenerator verwendet, der mit Hilfe der transportablen Cs-Fontänenuhr FOM des BNM-SYRTE/ENS, Paris stabilisiert wurde. Ein Vergleich mit der Messung aus dem Jahr 1999 ergibt eine relative zeitliche Änderung der 1S-2S Frequenz von (-3,2+-6,3)*10^(-15)/Jahr. Mit diesem Wert und optischen Frequenzmessungen am 199Hg+ bzw. 171Yb+ Ion, die am NIST in Boulder/Colorado bzw. an der PTB in Braunschweig durchgeführt wurden, konnte eine Obergrenze für die gegenwärtige zeitliche Änderung der Feinstrukturkonstante von (d/dt)alpha/alpha=(-0,3+-2,0)*10^(-15)/Jahr angegeben werden. Dieser Wert ist mit Null verträglich. Für seine Herleitung wurden keine Annahmen über das zeitliche Verhalten der anderen Kopplungskonstanten gemacht. Die ermittelten Obergrenzen sind daher weitgehend modellunabhängig.

This work reports on experiments in which antihydrogen atoms have been produced in cryogenic Penning traps from antiproton and positron plasmas by two different methods and on experiments that have been carried out subsequently in order to investigate the antihydrogen atoms. By the first method antihydrogen atoms have been formed during the process of positron cooling of antiprotons in so called nested Penning traps and detected via a field ionization method. A linear dependence of the number of detected antihydrogen atoms on the number of positrons has been found. A measurement of the state distribution has revealed that the antihydrogen atoms are formed in highly excited states. This suggests along with the high production rate that the antihydrogen atoms are formed by three-body recombination processes and subsequent collisional deexcitations. However current theory cannot yet account for the measured state distribution. Typical radii of the detected antihydrogen atoms lie in the range between 0.4 µm and 0.15 µm. The deepest bound antihydrogen atoms have radii below 0.1 µm. Antihydrogen atoms with that size have chaotic positron orbits so that for the first time antihydrogen atoms have been detected that cannot be described by the GCA-model. The kinetic energy of the weakest bound antihydrogen atoms has been measured to about 200 meV, which corresponds to an antihydrogen velocity of approximately 6200 m/s. A simple model suggests that these atoms are formed from only one deexcitation collision and methods that might lead to a decrease of the antihydrogen velocity are presented. By the second method antihydrogen atoms have been synthesized in charge-exchange processes. Lasers are used to produce a Rydberg cesium beam within the cryogenic Penning trap that collides with trapped positrons so that Rydberg positronium atoms are formed via charge-exchange reactions. Due to their charge neutrality the Rydberg positronium atoms are free to leave the positron trapping region. The Rydberg positronium atoms that collide with nearby stored antiprotons form antihydrogen atoms in charge-exchange reactions. So far, 14 +/- 4 antihydrogen atoms have been detected background-free via a field-ionization method. The antihydrogen atoms produced via the two-step charge-exchange mechanism are expected to have a temperature of 4.2 K, the temperature of the antiprotons from which they are formed. A method is proposed by which the antihydrogen temperature can be determined with an accuracy of better than 1 K from a measurement of the time delay between antihydrogen annihilation events and the laser pulse that initiates the antihydrogen production via the production of Rydberg cesium atoms. First experiments have been carried out during the last days of the 2004 beam time, but the number of detected antihydrogen annihilations has been too low for a determination of the antihydrogen temperature. Trapped antiprotons have been directly exposed to laser light delivered by a Titanium:Sapphire laser in order to investigate if the laser light causes any loss on the trapped antiprotons. Experiments have shown that no extra loss occurs for laser powers of less than 590 mW. This is an important result against the background of the future plan to confine antihydrogen atoms in a combined Penning-Ioffe trap and then to carry out laser spectroscopy on these atoms, since it reveals that laser light does not cause an increase of the pressure in the trapping region to the extend that annihilations with the background gas become noticeable. The ATRAP Collaboration plans to precisely investigate antihydrogen atoms. The ultimate goal is to test the CPT-theorem by a high precision measurement of the 1S-2S transition of antihydrogen and a comparison with the precisely known value of the corresponding transition in hydrogen. This thesis presents the achievement of the first step towards this challenging goal: the production of cold antihydrogen itself.

In der vorliegenden Arbeit werden die Weiterentwicklung des experimentellen Aufbaus zur 1S-2S-Zweiphotonenspektroskopie an atomarem Wasserstoff sowie die damit durchgeführten Messungen beschrieben. Die natürliche Linienbreite des dipolverbotenen 1S-2S-Übergangs ist mit 1,3 Hz sehr gering. Dieser Übergang kann durch Absorption zweier gegenläufiger Photonen bei einer Wellenlänge von 243 nm Doppler-frei angeregt werden. Für eine möglichst hohe Auflösung der Resonanz muß die den Übergang treibende Strahlung eines frequenzverdoppelten Farbstofflasers, dessen Fundamentale nahe 486 nm liegt, spektral schmal und stabil sein. Daher wird der Farbstofflaser auf einen Referenzresonator hoher Finesse stabilisiert. Der im Rahmen dieser Arbeit neu aufgebaute Referenzresonator wurde weitestgehend von Umwelteinflüssen entkoppelt, so daß die Drift des auf ihn stabilisierten Lasers nun weniger als 1 Hz/s und seine Linienbreite in 2 s weniger als 100 Hz bei 486 nm beträgt. Eine modifizierte Atomstrahlapparatur mit differentiell gepumptem Wechselwirkungsbereich und effizienterer Detektion der 2S-Atome erlaubt nun die Spektroskopie bei niedrigerer Lichtleistung und damit geringerer Verbreiterung des Übergangs durch Ionisation metastabiler Atome. Desweiteren können kältere Atome untersucht werden, deren Spektren kleinere geschwindigkeitsabhängige systematische Effekte aufweisen. Mit diesem Aufbau wurden Spektren einer Breite von nur 500 Hz bei 243 nm aufgenommen, was einer relativen Auflösung von 4x10^-13 entspricht. Nach Einführung einer differentiellen Meßmethode konnte die Hyperfeinaufspaltung des 2S-Niveaus in atomarem Wasserstoff erstmals mit optischen Methoden bestimmt werden, wobei das Ergebnis von 177 556 860(16) Hz den bisher genauesten Wert für diese Größe darstellt. Ein daraus abgeleiteter Test der QED gebundener Systeme bestätigt die Theorie auf einem Niveau von 1,2x10^-7. In Zusammenarbeit mit dem Frequenzkamm-Labor wurde die Frequenz des 1S-2S-Übergangs erneut gegen die transportable FOM-Cs-Fontände des BNM-SYRTE, Paris, absolut gemessen und zu 2 466 061 413 187 087(34) Hz bestimmt. Dies entspricht einer verbesserten relativen Auflösung von 1,4x10^-14. Im Vergleich mit dem Ergebnis der vorigen Messung aus dem Jahre 1999 und unter Berücksichtigung der Drift eines Uhrenübergangs in 199-Hg+ kann daraus erstmals eine obere Grenze für die relative Drift der Feinstrukturkonstanten von (-0,9 +- 2,9)x10^-15 pro Jahr abgeleitet werden, ohne daß zusätzliche Annahmen über die Stabilität der anderen Kopplungskonstanten getroffen werden müsssen. Diese Drift ist im Rahmen des Fehlers mit Null verträglich.

In the course of this work a new technique to measure the frequency of light has been developed, implemented and refined. For all time and frequency measurements the SI second defined by the cesium ground state hyperfine splitting near 9.2 GHz is the defined standard of reference. Therefore in precision optical frequency measurements optical frequencies on the order of several 100 THz – too fast to be counted with any electronics – have to be compared with radio frequencies on the order of a few GHz. The basic idea here is to measure dierences between optical frequencies with the help of frequency combs generated by the periodic pulse trains of femtosecond lasers. The output spectrum of such a laser consists of modes equally spaced by the repetition frequency of the pulses and forms a convenient ruler in frequency space. Extending this principle to the intervals between harmonics of the same optical frequency f, in the most simple case the interval between f and 2f, allows the absolute measurement of an optical frequency f = 2f − f. To bridge the interval between an optical frequency f and its second harmonic 2f a broad frequency comb with a width of several 100 THz is needed. This can be achieved with very short pulses (on the order of 5 fs) or with moderately short pulses on the order of a few 10 fs via self phase modulation in an optical fiber. Especially suited for such massive broadening are so called photonic crystal fibers. Here the light is guided in a very small core (1-2 µm) surrounded by air holes. This development culminates in the “single laser frequency chain” linking the radio frequency domain with the optical domain with the help of just one fs laser, a piece of fiber and some optics. Our optical frequency synthesizer can be used to measure not only one but almost any optical frequency with the same compact apparatus. Originally this project has been initiated to perform precision spectroscopy on the 1S- 2S transition in atomic hydrogen, a project with a long tradition in our group, and yielded what is thus far the most precise optical frequency measurement with a relative uncertainty of 1.8×10−14. Hydrogen as the most simple bound system served and still serves as an important cornerstone for tests of quantum physics, the measurement of the 1S Lamb shift represents one of the most accurate QED tests. Furthermore the Rydberg constant can be determined very precisely from optical frequency measurements in hydrogen. Soon it became obvious that this technique has a broad applicability. In this work transition frequencies in cesium, indium and molecular iodine have been measured. Besides that principle tests on this technique have been conducted. The direct comparison of two such frequency chains showed agreement on the level of 5 × 10−16. Further applications besides precision spectroscopy can be found in the time domain. There it is now possible with this technique to control the phase evolution of ultra short light pulses and perform optical waveform synthesis. As optical clock work for future all optical clocks a fs frequency chain transfers stability and accuracy from the optical to the rf domain.