Programme
We are happy to announce the final program. Please note that small last minute changes might still be possible, this page however will always represent the latest version.
All the talks will take place in Zurich at University Irchel, in lecture room Y15-G-20. You can find directions here.
Final Program - List
Thursday 29th of June 2017
- 08:00 – 08:45:
- 08:45 – 09:00:
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09:00 – 09:30:
‹ ACES Scientific Objectives - From fundamental physics tests to time and frequency metrology ›
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Christophe Salomon Ecole Normale supérieure ACES Scientific Objectives - From fundamental physics tests to time and frequency metrology We will present the scientific objectives of the Atomic Clock Ensemble in Space mission, ACES [1]. ACES is composed of two atomic clocks to be launched to the International Space Station, a network of ultra-stable clocks on the ground, and space-to-ground time transfer systems in the microwave and optical range. The flight instruments are near completion and launch in space is expected in 2018. The ACES scientific objectives have four main components, the operation of a laser-cooled cesium primary standard in space (PHARAO), a precision measurement of the Einstein effect, the gravitational shift of the clock frequency predicted by General Relativity, tests of Lorentz invariance, and a search for time or spatial variations of fundamental physical constants by long-distance clock comparisons. In this talk we will review these objectives in the broader context of space clocks and time and frequency metrology. [1] P. Laurent, D. Massonnet, L. Cacciapuoti, C. Salomon, The ACES /PHARAO Space Mission, Comptes-Rendus Acad. Sciences, Paris, 16, 540 (2015)
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09:30 – 10:00:
‹ ACES Mission Status ›
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Luigi Cacciapuoti European Space Agency ACES Mission Status Atomic Clock Ensemble in Space is an ESA mission designed to test Einstein’s Equivalence Principle with high-performance atomic clocks in space. Installed on-board the International Space Station, the ACES payload will generate a clock signal with fractional frequency instability and inaccuracy of $1\cdot10^{-16}$. Two high-performance links, operating on microwave (MWL) and optical (ELT) frequencies, will allow comparing the ACES clocks with the best atomic clocks on the ground in a global network. Space-to-ground and ground-to-ground comparisons will provide tests of Einstein’s theory of general relativity, at the same time developing applications in geodesy and time & frequency metrology. The ACES flight model is close to completion. The cold atom clock PHARAO has been tested and delivered for integration in the ACES payload. The ELT link has been completed. MWL and the active hydrogen maser SHM are presently under test. Integrated tests at system level have started and will continue all along 2017. This paper will present the recent progress of the ACES mission and discuss future perspectives for testing fundamental physics with clocks in space.
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10:00 – 10:30:
‹ Status of Experimental Gravity ›
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Claus Laemmerzahl ZARM - Center of Applied Space Technology and Microgravity Status of Experimental Gravity A short overview is given about the foundations of General Relativity and the corresponding tests. This is mainly related to the Einstein Equivalence Principle. After having established the formalism of General Relativity, its consequences will be described as well as their experimental confirmation. The talk will end by listing some open fundamental issues, mainly related to the question of quantum mechanics and gravitation.
- 10:30 – 11:00: Coffee Break
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11:00 – 11:30:
‹ ACES MWL data processing center at SYRTE ›
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Peter Wolf SYRTE - Obervatoire de Paris ACES MWL data processing center at SYRTE The ACES-PHARAO mission aims at operating a cold-atom caesium clock on board the International Space Station, and performs two-way time transfer with ground terminals, in order to allow highly accurate and stable comparisons of its internal timescale with those found in various metrology institutes. Scientific goals in fundamental physics include tests of the gravitational redshift with unprecedented accuracy, and search for a violation of the Lorentz local invariance. As launch is coming closer we are getting ready to process the data expected to come from ACES Microwave Link (MWL) once on board the International Space Station. Several hurdles have been cleared in our software in the past months, as we managed to implement algorithms that reach target accuracy for ground/space desynchronisation measurement. We are using that software to carry out performance tests and study the influence of expected systematic effects like e.g. uncertainties in ISS orbit determination.
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11:30 – 12:00:
‹ Accuracy Evaluation of PHARAO: the Microwave Lensing, Cavity Phase, and Collision Frequency Shifts ›
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Kurt Gibble Penn State University Accuracy Evaluation of PHARAO: the Microwave Lensing, Cavity Phase, and Collision Frequency Shifts The accuracy evaluation of PHARAO is needed for the ACES mission to achieve its science goals. Three important sources of systematic uncertainty of PHARAO are the frequency shift due to the microwave lensing, a first-order Doppler shift, known as cavity phase shifts, and the collisional frequency shift. We modeled these shifts in detail. The corrected bias for microwave lensing is 1.15 \times 10^{-16}, comparable to the accuracy goal of PHARAO. We use large, densely-meshed, three-dimensional finite-element models of the microwave fields in the clock cavity to calculate representative cavity phase shifts. The evaluation of cavity phase for PHARAO will be significantly different than for fountain clocks. Taking advantage of the ability to change the launch velocity by an order of magnitude in microgravity, the representative cavity phase shifts can be extrapolated to the limit of zero launch velocity with systematic errors less than 10^{-16}. With a model of the PHARAO frequency stability, we have optimized the operation of PHARAO for the averaging time spent at two cloud densities for three launch velocities. These lead to a statistical uncertainty of the combined cavity phase and collision shift that can be averaged to below the PHARAO accuracy goal of 10^{-16}.
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12:00 – 12:30:
‹ New constraints on Lorentz symmetry with nucleons in a Cs fountain and perspectives for the ACES mission ›
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Christine Guerlin LKB/SYRTE New constraints on Lorentz symmetry with nucleons in a Cs fountain and perspectives for the ACES mission Alternative theories describing physics at the Planck scale can to lead to deviations from known physics also at low energy. In particular, the spacetime symmetry encapsulating special relativity, Lorentz invariance, could be broken. Testing Lorentz invariance with low-energy experiments using the high precision of metrology experiments is thus one approach to fundamental tests. We recently pursued several such analyses at SYRTE and LKB, in the Standard-Model Extension (SME) theoretical framework. By parametrizing a set of deviations from Lorentz symmetry at the level of the Lagrangian, the SME allows us to model a wide class of measurements and to express their constraints in terms of a common finite set of coefficients. By re-analyzing spin-polarized fountain clock data spread over half a year with an improved description of its center of mass velocity, and with a more refined description of the nuclear properties, we were able to set new constraints on proton and neutron coefficients in the matter sector, with improvements by up to 13 orders of magnitude. We will report on our new model, data analysis and the Cs clock constraints obtained. This test was initially considered regarding its perspectives for the ACES mission. A suitable spin-polarized measurement mode has been consequently planned on the PHARAO control software. We will give the improvement perspectives estimated for realizing this test on PHARAO during the ACES mission, obtained by simulation.
- 12:30 – 14:00: Lunch Break
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14:00 – 14:30:
‹ Constraining models of extended gravity using Gravity Probe B and LARES experiments ›
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Salvatore Capozziello Università di Napoli Constraining models of extended gravity using Gravity Probe B and LARES experiments We consider models of extended gravity and in particular, generic models containing scalar-tensor and higher-order curvature terms, as well as a model derived fro non-commutative spectral geometry. Studying, in the weak-field approximation (the Newtonian and post-Newtonian limit of the theory), the geodesic and Lense-Thirring processions, we impose constraints on the free parameters of such models by using the recent experimental results of the Gravity Probe B (GPB) and Laser Relativity Satellite (LARES) satellites. The imposed constraint by GPB and LARES is independent of the torsion-balance experiment, though it is much weaker.
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14:30 – 15:00:
‹ Clock networks and relativistic geodesy ›
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Jakob Flury Leibniz Universität Hannover Clock networks and relativistic geodesy
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15:00 – 15:30:
‹ Progress towards a European metrological fiber network: current status and prospects ›
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Harald Schnatz Technische Universität München Progress towards a European metrological fiber network: current status and prospects Today’s optical clocks (OC) can reach a fractional frequency uncertainty of better than one part in 1017 and outperform the best caesium (Cs)-based atomic clocks in terms of both accuracy and stability. They are promising candidates the redefinition of the unit of time, and an ideal tool for tests of theories in fundamental physics such as the search for varying fundamental constants, as well as candidates for clocks in space or novel applications in radio astronomy or geodesy. However, to take advantage of the full potential of OCs requires such clocks being compared on a regular basis and at the corresponding level of uncertainty. Currently the only method to compare OCs or to disseminate ultra-stable reference frequencies to remote users is based on frequency transfer by means of optical fibers. I will introduce current achievements obtained by operating long-distance optical fibre links between national metrology institutes or remote end users, present some recent applications of frequency and time transfer over optical fibers and discuss the prospects of a potential European metrology network.
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15:30 – 16:00:
‹ Delay compensated Optical Time and Frequency Distribution for Space Geodesy ›
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Ulrich Schreiber Technische Universität München Delay compensated Optical Time and Frequency Distribution for Space Geodesy an all optical two-way system, which allows the campus synchronization of a distributed set of geodetic measurement system in time and frequency with an accuracy of 1 ps. The goal is to make it possible to eventually use time as an observable and not as an adjustment parameter in a non-linear fitting process. With a centralized fs- pulse laser and a star like fiber network it is possible to reference all measurements to the same time scale and to control system biases. This opens the door to accurate closure measurements of system delays within each geodetic measurement technique and from one technique to the next (e.g. from SLR to VLBI).
- 16:00 – 16:30: Coffee Break
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16:30 – 16:50:
‹ Galileo gravitational Redshift test with Eccentric sATellites (GREAT) ›
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Pacôme Delva SYRTE/Observatoire de Paris Galileo gravitational Redshift test with Eccentric sATellites (GREAT) Clocks on-board GNSS satellites can be used to perform an improved test of the gravitational redshift if they are placed on an elliptical orbit around Earth. As proposed in Delva et al. (Classical and Quantum Gravity 32.23 (2015) p 232003), we use signals from Galileo satellites 5 and 6 (GAL-201 and GAL-202) to perform such a test. ESA is funding two parallel studies, named Galileo gravitational Redshift test with Eccentric sATellites (GREAT), led by SYRTE/Observatoire de Paris and ZARM. An elliptical orbit induces a periodic modulation of the gravitational redshift at the orbital frequency. Since these spacecraft have atomic clocks with good stability, a test of the variation of the redshift can be performed and an accumulated relativistic effect can be determined over the long term. SLR data are required to characterize the orbital radial errors, which are highly correlated to clock errors in IGS orbit solutions. The ILRS support the GREAT experiment by initiating a one-year campaign of SLR with Galileo satellites 5 and 6. We present the current status of this campaign, and a first analysis of the SLR data in order to estimate the systematic effects coming from the orbital errors on the GR violation parameter.
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16:50 – 17:10:
‹ Creating the First Bose-Einstein Condensate in Space ›
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Stephan Tobias Seidel Institut für Quantenoptik - Leibniz Universität Hannover Creating the First Bose-Einstein Condensate in Space On January 23rd 2017 the first Bose-Einstein Condensate (BEC) in space was created on board the sounding rocket mission MAIUS-1. Its successful launch marks a major advancement in the effort of performing matter wave interferometry with BECs on spacecrafts. Due to the fast BEC creation possible with the apparatus more than 100 experiments were conducted during the suborbital flight. These include an observation of the phase transition in microgravity, the free BEC evolution, state preparation, and the creation of cold atoms in highly dynamic environments. MAIUS-1 opens a new path towards space borne inertial sensing employing interferometers with high accuracy and sensitivity. Recently several missions were proposed ranging from tests of the universality of free fall to gravity gradiometry for earth observation. Due to their small initial size and low expansion rates BECs are the ideal source for such interferometric measurements. MAIUS-1 will be followed by two sounding rocket missions where dual-species atom interferometry will be investigated. The results of the mission will also contribute to NASA’s CAL project and German-American BECCAL experiment planned for the International Space Station. In this talk an overview of the flight, the apparatus flown as well as the key results achieved will be presented.
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17:10 – 17:30:
‹ Optical Laser Time Transfer for accurate Clocks in Space ›
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Pierre Exertier CNRS-OCA Optical Laser Time Transfer for accurate Clocks in Space Optical time transfer has demonstrated impressively its suitability for accurate time comparisons between clocks on the ground and in space. While the T2L2 project was in the end limited by the stability of the satellite clock (an Ultra-Stable-Oscillator) after 100 seconds, the ELT project will allow the accurate comparison between h-maser systems on the ground and an Atomic Clock Ensemble in Space. This talk will outline the achievements and the potential of the optical 2-way ranging technique for comparing time between ground and space.
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17:30 – 17:50:
‹ Relativistic Celestial Metrology: Dark Matter as an Inertial Gauge Effect ›
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Luca Lusanna Relativistic Celestial Metrology: Dark Matter as an Inertial Gauge Effect In canonical tetrad gravity it is possible to identify the gauge variables, describing relativistic inertial effects, in Einstein general relativity. One of these is the York time, the trace of the extrinsic curvature of the instantaneous non-Euclidean 3-spaces (global Euclidean 3-spaces are forbidden by the equivalence principle: the extrinsic curvature depends both on gauge variables and on dynamical ones like the gravitational waves after linearization). The fixation of these gauge variables is done by relativistic metrology with its identification of time and space. Till now the International Celestial Reference Frame ICRF uses Euclidean 3-spaces outside the Solar System. It is shown that York time and non-Euclidean 3-spaces may explain the main signatures of dark matter in ordinary space-time before using cosmology. Also dark energy may be connected to these inertial gauge effects, because both red-shift and luminosity distance depend on them.
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17:50 – 18:10:
‹ Clocks and cold atoms for testing electromagnetism ›
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Alessandro D.A.M. Spallicci Université d'Orléans - CNRS Clocks and cold atoms for testing electromagnetism Photons are the messengers from the Universe and the sole massless particles of the Standard model. In fundamental physics testing electromagnetism (massive or non-linear) against Maxwell XIX theory, clocks and cold atoms could play a significant role. Results Photon mass upper limit. - Ampère’s law in solar wind through Cluster spacecraft data [6]. - Time lag of photons from FRBs [2,4] - Time lag at low frequencies (10 KHz – 10 MHz) through nanosatellites swarm [1]. Photon mass origin - Super and Lorentz symmetry breaking [3]. Frequency shift - Magnetic field (magnetar) causes red or blue shift [5]. [1] Bentum M.J., Bonetti L., Spallicci A.D.A.M., 2017. Adv. Sp. Res., 59, 736. [2] Bonetti L., Ellis J., Mavromatos N.E., Sakharov A.S., Sarkisyan-Grinbaum E.K.G., Spallicci A.D.A.M., 2016. Phys. Lett. B, 757, 548. [3] Bonetti L., dos Santos Filho L.R., Helayël-Neto J.A., Spallicci A.D.A.M., 2017. Phys. Lett. B, 764, 203. [4] Bonetti L., Ellis J., Mavromatos N.E., Sakharov A.S., Sarkisyan-Grinbaum E.K.G., Spallicci A.D.A.M., 2017. Phys. Lett. B, 768, 326. [5] Bonetti L., Perez Bergliaffa S.E., Spallicci A.D.A.M., 2017, 14 M. Grossmann, World Scientific, arXiv:1610.05655 [astro-ph.HE]. [6] Retinò A., Spallicci A.D.A.M., Vaivads A., 2016. Astropart. Phys., 82, 49.
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18:10 – 18:30:
‹ Searching for dark matter with atomic clocks in space ›
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Tigran Kalaydzhyan Jet Propulsion Laboratory Searching for dark matter with atomic clocks in space We will discuss existing and new methods of the dark matter direct detection with the use of atomic clocks on ground and in space. After explaining the main methodology, we will provide some concrete examples on the sensitivities for the future atomic clocks at the International Space Station, including ACES.
- 19:30 – 22:30:
Chair: U. Schreiber
Chair: L. Cacciapuoti
Friday 30th of June 2017
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08:30 – 09:00:
‹ Preliminary results of MICROSCOPE mission ›
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Manuel Rodrigues ONERA Preliminary results of MICROSCOPE mission The MICROSCOPE satellite has been launched on April the 25th of 2016. Since, thousands of orbit science data have been cumulated. The space mission aims at testing the Equivalence Principle with an accuracy of 1E-15, two orders of magnitude better than ground tests. After the 6 months of the commissioning phase, the CNES’ microsatellite and the ONERA’s science payload has been declared ready for science. The payload is composed of two double accelerometers: one with two test-masses made of the same PtRh material (SUREF: sensor unit of reference), the other one made of PtRh and Ti (SUEP: sensor unit for the EP test). The difference of measured acceleration on SUEP, in phase with the Earth’s gravity filed, should be null if the EP is not violated. The SUREF serves to check the measurements quality and data processes as no signal is expected. The mission should last until 2018 and more science data should be collected. The main work to come is to combine all the collected data into a final result expected for end of 2018. Nevertheless, the MICROSCOPE team can present a halfway result. After a presentation of the mission principles and a description of the science payload, we will focus on the preliminary results already validated.
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09:00 – 09:30:
‹ Testing Lorentz symmetry from space with MICROSCOPE ›
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Hélène Pihan-Le Bars SYRTE - Observatoire de Paris Testing Lorentz symmetry from space with MICROSCOPE The MICROSCOPE mission, currently operating, will perform a Weak Equivalence Principle test at the unprecedented uncertainty of 10-15. Here, we are interested in testing another assumption of General Relativity (GR): the local Lorentz invariance, which states the invariance of local non gravitational experiments under velocity and orientation changes. Such invariance under local Lorentz transformations exists as well in the Standard Model (SM). The search of Lorentz violation signals at low energy can be done using an exhaustive theoretical framework, called the Standard Model Extension (SME), which includes all possible observer invariant Lorentz violating terms that can be build from SM and GR fields. The amplitude of these violating terms are controlled by coefficients that need to be constrained experimentally. Through the measurement of the differential acceleration of two test masses with different compositions, MICROSCOPE should allow us to set strong constraints on several species dependent SME coefficients characterizing an unusual coupling between matter and gravitational fields. We will present the status of the SME analysis of MICROSCOPE data, which is currently ongoing at SYRTE: toy-model adjustment on simulated data provided by ONERA/OCA are presently performed and we are also working on the implementation of statistical methods based on realistic noise simulations.
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09:30 – 10:00:
‹ Mission I-SOC: an optical clock on the ISS ›
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Stephan Schiller Heinrich-Heine-Universität Düsseldorf Mission I-SOC: an optical clock on the ISS The ESA mission "Space Optical Clock on the ISS", I-SOC, aims at operating an optical lattice clock on the ISS in 2022+. The mission is the natural follow-on of the ACES mission. The scientific goals of the mission are to perform tests of fundamental physics (Einstein’s gravitational time dilation), to enable space-assisted relativistic geodesy, and to intercompare optical clocks on the ground at the $1\times10^{-18}$ level. The geodesy goal will allow the determination of the local gravity potential with accuracy at equivalent level of 1 cm within 1 day measurement time. Comparison of ground clocks via the ISS will be performed using enhanced MWL and ELT. The space clock’s specification is $1\times10^{-17}$ inaccuracy, mass approximately 100 kg, power consumption of 250 W. A modular, transportable breadboard demonstrator has been developed and has reached less than $2\times10^{-17}$ instability. Critical technology development is under way, funded by ESA.
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10:00 – 10:30:
‹ Next generation optical lattice clocks ›
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Ross Hutson JILA, NIST and University of Colorado Boulder Next generation optical lattice clocks Ongoing advances in atomic clocks enable table top searches of dark matter and other physics beyond the Standard Model, as well as provide new tools for studies of quantum many-body systems. Currently the most accurate and stable clocks are based on alkaline-earth(-like) neutral atoms confined to one-dimensional optical lattices. A major obstacle in improving clock stability and accuracy is mitigating density-dependent frequency shifts due to contact interactions. We overcome this limitation by loading a degenerate Fermi gas of strontium atoms into a three-dimensional optical lattice where contact interactions become spectroscopically resolvable. We demonstrate the novelty of this system with a number of different experiments: (1) By carefully controlling the lattice ac Stark shifts we observe sub 100 mHz spectroscopic features with $1\times 10^4$ atoms; (2) By spatially resolving the atomic excitation fraction we perform a synchronous clock comparison between two regions of the gas, achieving a fractional frequency instability at the low $10^{-17} / \sqrt{\tau}$ level; (3) We observe SU(10)-symmetric, effective three-body interactions by resolving frequency shifts in multiply occupied sites. With a different set of experiments, We will discuss how optical spectroscopy can be used to engineer non-trivial topological band structures and how these ideas may be used to build better clocks.
- 10:30 – 11:00: Coffee Break
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11:00 – 11:20:
‹ ACES Development and Integration Status ›
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Marc Peter Heß Airbus DS GmbH ACES Development and Integration Status The Atomic Clock Ensemble in Space project executed by Airbus comprises the development and integration of the ACES payload, the network of MicroWave Link (MWL) Ground Terminals and the ACES Ground Segment. The payload flight model is under integration with system tests started in 2016. Based on test observations and new requirements the design baseline has evolved by implementing an on-orbit degaussing feature for the Space Hydrogen Maser (SHM) and coatings to the Corner Cube Reflector to avoid interfering with ISS visiting vehicles. The SHM and MWL Flight Segment are being integrated today. The first MWL Ground Terminal has been deployed at PTB (Braunschweig) and 8 recurring units are built. The ground segment, delivered to CADMOS(Toulouse) in 2014 is gradually refined and upgraded including its Data Post-Processing functions. This paper will present the actual configuration and development status of the different elements and will provide an outlook to the functional, performance and environmental tests planned to demonstrate all mission objectives are met and the payload can sustain the launch and space environment.
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11:20 – 11:40:
‹ Recent achievements in photon counting laser time transfer ›
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Ivan Prochazka Czech Technical University in Prague Recent achievements in photon counting laser time transfer The laser time transfer ground to space is an attractive technique to compare the ultra-stable clocks on ground and in space. The photon counting approach enables to reduce significantly the systematic errors of the measurement chain. For ACES mission the European Laser Timing system was designed, constructed and extensively tested. The final test results will be presented. For the space mission nominated for the next decade the increased precision and long term detection delay stability both on sub-picosecond level are required. We have developed new devices: optical detectors and timing systems for laser time transfer ground to space with extremely high timing precision and stability. The limiting precision of laser time transfer instrumental chain characterized by time deviation TDEV is well below 100fs for 100s averaging time. The long term timing stability is better than 1ps over days of operation. The devices are constructed on a basis of electronics components for which the space qualified equivalents are available. The construction of the devices and their tests results will be presented in detail.
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11:40 – 12:00:
‹ Optical Time Transfer and its Impact on System Biases ›
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Jan Kodet Technische Universität München Optical Time Transfer and its Impact on System Biases The classical approach in space geodesy is to treat individual systems separately and combine their measurements using co-located sites. The approach co-locations of the space geodetic instrumentation is to regularly measure local ties between the reference points. In such an approach the reference points are monitored using geometry and physical dimensions of the instrumentations. Time in this concept is not an observable in its own way, however is computed from redundant number of observations for different systems separately. A stable atomic clock in a precisely defined orbit would enable to concern geodetic measurement in closure measurement via the timing system. In such a concept the measurement signal path and the inter- technique are creating loop measurement, which is closed through the clock. The talk outlines closure measurement concept with the first results, derived at Geodetic Observatory Wettzell to provides both, intra- and inter- technique comparisons and delay control through multi-technique ground target.
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12:00 – 12:20:
‹ Simulation study on ELT time transfer ›
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Stefan Marz Technical University of Munich Simulation study on ELT time transfer The European Laser Timing (ELT) experiment, as part of the ACES mission, aims to establish, next to the microwave link, also an optical time transfer between SLR station clocks and the clock aboard the International Space Station with picosecond accuracy. For this purpose, both a classical two-way and an additional one-way optical link shall be established, based on timing via ultra-short laser pulses. The ELT Data Center, which is responsible to provide the ACES module tracking information needed by SLR stations, implemented a simulation and evaluation program according to this experiment. Within this program several parameters, such as the laser pulse length, path length, background noise, clock accuracy and maximum elevation, can be varied to test the along going influence. In doing so, we will present the influences of these parameters regarding the realization and accuracy of ELT.
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12:20 – 12:40:
‹ Ground station requirements for optical Time Transfer ›
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Johann Eckl Geodetic Observatory Wettzell, Federal Agency for Cartography and Geodesy, Germany Ground station requirements for optical Time Transfer When is comes to precise orbit determination in geodesy, Satellite Laser Ranging is the state of the art technology. Therefore, the geometrical reference point of the ground stations is well defined in space. Upgarding these systems with highly accurate clocks in combination with a good definition and stability of the local reference points in time would enable this technique for highly accurate and precise optical time transfer between space and ground. As a consequence the stations will become reference points in time as well. We report on the performance and the requirements for optical ground stations for time and frequency transfer to space and the potential of this technique.
- 12:40 – 14:00: Lunch Break
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14:00 – 14:20:
‹ GFZ Potsdam contributions to ELT ›
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Sven Bauer GFZ Potsdam GFZ Potsdam contributions to ELT The upcoming European Laser Timing (ELT) experiment onboard the International Space Station consists of a laser detector, which is connected to the Atomic Clock Ensemble in Space (ACES), as well as a Laser Retro Reflector (LRR). GFZ Potsdam, developed, built and delivered this LRR to Airbus/ESA. The flight proven unit is passive, small (100x100x48 mm), lightweight (400 gram) and provides two-way ranges at an accuracy better than 1 cm. In combination with one-way ranges to the detector, accurate ground to space and ground to ground time transfer between laser ground stations in common and non-common view will be possible. Beside ground stations featuring various observation techniques and accurate clocks also national and international metrology institutes would benefit from an accurate comparison of their clocks via ELT. At GFZ Potsdam we are currently exploring the feasibility of connecting our local atomic clock to the timescale of the Physikalisch Technische Bundesanstalt (PTB) in Braunschweig via a fiber-optical link, in order to provide it world-wide via laser ranging to ELT. The utilized one-way ranges would only be affected by the transmit path delay of a laser ground station. Techniques to measure this delay individually from the total path delay are currently under development.
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14:20 – 14:40:
‹ ACES microwave link-related activities at the National Physical Laboratory ›
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Setnam Shemar National Physical Laboratory ACES microwave link-related activities at the National Physical Laboratory We present an overview of the ACES activities at the National Physical Laboratory (NPL). Firstly, we describe the planned installation of an ACES MicroWave Link (MWL) ground terminal at NPL, concentrating on the frequency distribution between NPL’s reference H-maser, caesium fountains and optical clocks in one building and the site of the terminal at a second building 500 m away. To meet the stringent requirements of ACES, the aim is to have a link between the two buildings with a Time Deviation of 0.3 ps at an averaging time of 1E5 s. We present test results obtained using a commercial phase-compensated optical fibre transfer system. An assessment of the RF interference environment at the future site of the terminal is also outlined. Secondly, we briefly describe a recently-started one-year study to investigate data analysis methods for the MWL. We summarise the main objectives of this, which include simulating ACES MWL output data to test the analysis methods. The aim is that once ACES is operational, the software will be used to support comparisons between space and ground clocks, and to investigate potential future GNSS performance using improved space clocks.
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14:40 – 15:00:
‹ ASI activities for space quantum communication and metrology ›
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Mario Siciliani de Cumis Agenzia Spaziale Italiana ASI activities for space quantum communication and metrology The Matera laser ranging observatory (MLRO) is playing a primary role for Space Quantum Communication (SQC) and soon also for Metrology thanks to the Primary Standard disseminated by INRIM via optical fiber. The milestones in SQC span from the first single photon transmission from a low Earth orbit satellite (LEO) in 2008 to the realization of the first transmission of quantum states from several LEO satellites and the demonstration of single photon exchange from medium Earth orbit satellite, fostering the expansion of quantum communications to the global navigation satellite system constellations. In addition, an optical fiber link of 1300 km from Turin (INRIM) to Matera (MLRO) is currently underway. The incoming laser will be phase-stabilized according to the Doppler noise cancellation scheme. Regeneration and fiber phase-noise cancellation is planned in Florence and Naples. For the route Turin-Florence an improvement of the measurement resolution by almost three orders of magnitude with respect to the GPS-disciplined clocks has been demonstrated. Peculiarities and upgrades foreseen of MLRO will be crucial for achievements in VLBI applications, laser ranging and laser timing experiments. In view of the expansion of ASI activity, the station is planning a series of improvements that could support ACES experiment.
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15:00 – 15:20:
‹ ACES from the viewpoint of geodesy ›
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Anja Schlicht TU Munich ACES from the viewpoint of geodesy A major challenge of modern geodesy is the combination of space techniques on observation level making it necessary to evaluate and parameterize systematic effects on each technique. Evaluating systematic effects can be done by collocating multiple techniques on ground, so called GGOS stations, as well as in space, like the proposed mission GRASP or E-GRASP. ACES now will be the first mission where two high precision ranging techniques, an optical and one based on microwaves, are collocated in space and on ground. On this mission we can work-out and test a common estimation procedure which is not disturbed by great systematic effects, like multipass on GNSS. We can evaluate the combination of MWL and SLR/ELT in many aspects and show the benefit of time transfer, turning pseudo-ranges to biased ranges. In this talk we show how ACES and the heritage of ACES fits into a future concept of Galileo intersatellite links (GOISL) and even in a greater step into the future in a concept of a Geodesy and Time Reference in Space (GETRIS).
- 15:20 – 15:40: Coffee Break
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15:40 – 16:00:
‹ Frequency combs in space: Design considerations, recent experiments, and future applications ›
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Matthias Lezius Menlo Systems GmbH Frequency combs in space: Design considerations, recent experiments, and future applications The status of our frequency combs and ultra-stable reference lasers for space applications will be reviewed. Special consideration will be given to applications with relevance to ACES: Clock comparisons, microwave generation, long-distance fiber frequency and timing links, ground station equipment, and the operation of future space based optical clocks.
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16:00 – 16:20:
‹ Progress at UWA for Participation in ACES ›
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Michael Tobar The University of Western Australia Progress at UWA for Participation in ACES An update on Australian participation in ACES will be presented. This includes the following: 1) An update on the optical clock and other precision frequency synthesis at UWA. 2) An update on upgrading the Yarragadee Laser Ranging Station for participation in ACES. 3) Our efforts to connect the UWA clock ensemble to the Yarragadee Laser Ranging Station. 4) A report on our latest test on fundamental physics using our rotating quartz oscillators to tests Lorentz Invariance in the phonon sector, and precision tests to search for axion dark matter.
- 16:20 – 16:50:
Chair: P. Wolf
Chair: Ch. Salomon
Final Program - Schedule
Conference Dinner
The dinner will take place in LaSalle, Zurich.