Mission I-SOC: An optical clock on the ISS Coordinator: S. Schiller (Univ. Düsseldorf) U. Sterr Ch. Lisdat R. Le Targat J. Lodewyck Y. Singh K. Bongs N. Poli G.M. Tino F. Levi I. Prochazka
Prelude When ACES was proposed in 1997 … … Optical clocks were appearing in a few labs – primarily single-ion clocks … transportable clocks of high accuracy were a dream … the frequency comb did not exist … long-distance clock comparisons at 10 -19 level were a dream … robust lasers for visible wavelengths and high power were just appearing Review: Poli et al. Nuovo Cimento (2013) Ludlow et al. RMP (2015)
Going optical For ACES, optical ground clocks, combs and links now are a key mission component However, the impressive progress of ground clock performance calls for a post-ACES means of comparing them Improvements in ground and space technology (revolutionary & evolutionary) allow improvement by 10 – 100 in science output compared to ACES … leveraging on ACES heritage, we expect a cost smaller than that of ACES Systematic errors understanding must improve correspondingly -> optimistic perspective (talk by P. Wolf) It is important to develop the I-SOC clock and to implement I-SOC within a reasonable time following ACES, in order to maintain its know-how and heritage (technology, clock operations, MWL operations, data analysis, …) S. Schiller, ACES Workshop Zürich, 29.-30. 6. 2017
From ACES to I-SOC Same location, similar system concept, but optical As in ACES, OSRC is the local oscillator; is steered to the atoms on the long time scale In contrast to ACES, SLOC contains no own oscillator Frequency comb is phase-locked to clock laser FDP contains a USO for backup No frequency-comb based optical link (cost, mass & power) Upgraded MWL (MWL) 100 MHz Upgraded Space ELT (ELT+) frequency comb (SFC) 10 GHz Space lattice 429 THz Optical cavity clock (SLOC) + laser („clock laser“, OSRC) Laser bench
ACES and I-SOC • ACES actual/estimated performance vs. I-SOC requirements ACES I-SOC * Improvem. 8 x 10 -16 / 1/2 (up to 2×10 6 s) 1x10 -13 / 1/2 Clock instability x 100 Clock inaccuracy 1x10 -16 1x10 -17 x 10 1.5 ps ×( /10 000 s) 1/2 MWL / MWL+ 0.03 ps ** x 150 @ 1 day 8 ps @ 10 6 s 1 ps @ 10 6 s ELT / ELT+ x 8 Phase coherence yes yes, minimum 12 h • I-SOC clock signal shall be phase-coherent → requirement to comb and SLOC ELT+ supports reaching 1×10 -18 ground clock comparisons (or ground-space) • • I-SOC performance can be tested fully on the ground ( trapped atoms) ** ground-to-space * from I-SOC ESR document
Consequences of I-SOC performance • Higher stability of ELT+ and MWL both allow clock comparisons at 10 -18 level AND within quiet ISS orbit intervals AND more quiet intervals to make use of • Higher stability of MWL and transportable high-performance optical clocks: allow doing geodetic surveys at 1 cm level (pairs of optical clocks compared in common-view), hundreds of field points • Higher stability of space clock: allows measuring its systematic effects in-situ more precisely
Ground stations Heritage from ACES (I) MWL ground stations: stationary & transportable (II) Ground stations with ELT+ For intercontinental clock comparisons: At least two SLR stations with ELT+, each with optical clock linked to it possibilities : Wettzell + future optical link to PTB Graz + transportable optical clock Yarragadee + link to UWA NICT (Tokio) + optical clocks Matera? US? For systematic tests: MWL and ELT+ at same SLR station with common linked ground clock Contributions welcome!
Mission I-SOC (Space Optical Clock on ISS) Scientific goals: (*) measure Earth‘s gravitational time dilation at 2 x 10 -7 level measure Sun‘s time dilation at 1 x 10 -6 level measure Moon‘s time dilation at 2 x 10 -4 level enable world-wide relativistic geodesy enable world-wide atomic time distribution enable world-wide clock comparisons search for dark matter topological defects Natural follow-on of ACES mission Mission of ESA in SciSpacE program; potential launch in 2022+ Optical lattice clock (SLOC) inaccuracy: <1 x 10 -17 ; instability: <1 x 10 -15 / 1/2 mass < 100 kg, power consumption < 250 W, volume < 0.5 m 3 MWL: current ESA study (SYRTE, DLR, Timetech) ELT+: Ivan Prochazka‘s talk SFC: M. Lezius‘ talk Data analysis: P. Wolf‘s talk
SOC breadboard demonstrator development (2010-15) Reference cavity Clock laser breadboard Atomic unit
Laser cooling and trapping Sr Blue MOT (461 nm) Red MOT (689 nm) Optical lattice (813 nm) 10 3 atoms T=1.3 μ K = 6.5 s T=3mK T<2 μ K 3 × 10 6 atoms 1 × 10 6 atoms z z I I y I y x I x CLEO/Europe-EQEC 2017, Munich S. Schiller, ACES Workshop Zürich, 29.-30. 6. 2017 29/06/17 10
Modular laser system 461 nm distribution 813 nm lattice 461 nm Reference cavity Repumper 679 nm Repumper 707 nm 698 nm clock laser 461, 689, 813 nm stabilization unit 689 nm stirring 689 nm cooling CLEO/Europe-EQEC 2017, Munich 29/06/17 11 S. Schiller, ACES Workshop Zürich, 29.-30. 6. 2017
Modular laser system 461 nm distribution 813 nm lattice 461 nm Reference cavity Repumper 679 nm Repumper 707 nm 698 nm clock laser • Relies on robust, mostly COTS, laser technology 461, 689, 813 nm stabilization unit 689 nm stirring 689 nm cooling • Units are exchangeable with improved ones Bongs, K. et al., “Development of a strontium optical lattice clock for the SOC mission on the ISS”, C. R. Phys. 16 , 553 (2015) CLEO/Europe-EQEC 2017, Munich 29/06/17 12 S. Schiller, ACES Workshop Zürich, 29.-30. 6. 2017
SOC: compact atomics package CLEO/Europe-EQEC 2017, Munich 29/06/17 13 S. Schiller, ACES Workshop Zürich, 29.-30. 6. 2017
SOC: compact atomics package Low power (20 W) atomic oven 1 1 M. Schioppo et al., Rev. Sci. Instrum. 83 , 103101 (2012) CLEO/Europe-EQEC 2017, Munich 29/06/17 14 S. Schiller, ACES Workshop Zürich, 29.-30. 6. 2017
SOC: compact atomics package Low power Permanent-magnets Zeeman (20 W) atomic oven 1 slower 2 1 M. Schioppo et al., Rev. Sci. Instrum. 83 , 103101 (2012) 2 I. R. Hill et al., J. Phys. B 47 , 075006 (2014) CLEO/Europe-EQEC 2017, Munich 29/06/17 15 S. Schiller, ACES Workshop Zürich, 29.-30. 6. 2017
SOC: compact atomics package Vacuum chamber Low power Permanent-magnets Zeeman (20 W) atomic oven 1 slower 2 1 M. Schioppo et al., Rev. Sci. Instrum. 83 , 103101 (2012) 2 I. R. Hill et al., J. Phys. B 47 , 075006 (2014) CLEO/Europe-EQEC 2017, Munich 29/06/17 16 S. Schiller, ACES Workshop Zürich, 29.-30. 6. 2017
SOC: compact atomics package Vacuum chamber Low power Small coils (5 W, no water Permanent-magnets Zeeman (20 W) atomic oven 1 cooling) slower 2 1 M. Schioppo et al., Rev. Sci. Instrum. 83 , 103101 (2012) 2 I. R. Hill et al., J. Phys. B 47 , 075006 (2014) CLEO/Europe-EQEC 2017, Munich 29/06/17 17 S. Schiller, ACES Workshop Zürich, 29.-30. 6. 2017
SOC: compact atomics package Temperature stabilization system (goal ∆ T<100 mK) Vacuum chamber Low power Small coils (5 W, no water Permanent-magnets Zeeman (20 W) atomic oven 1 cooling) slower 2 TECs (5W) + Heat pipes 1 M. Schioppo et al., Rev. Sci. Instrum. 83 , 103101 (2012) 2 I. R. Hill et al., J. Phys. B 47 , 075006 (2014) CLEO/Europe-EQEC 2017, Munich 29/06/17 18 S. Schiller, ACES Workshop Zürich, 29.-30. 6. 2017
Atomic package transport (June 2015) Birmingham Eurotunnel Braunschweig (PTB) CLEO/Europe-EQEC 2017, Munich 29/06/17 19 S. Schiller, ACES Workshop Zürich, 29.-30. 6. 2017
Clock laser integration Ś wierad et al., Sci. Rep. 6 , 33973 (2016) CLEO/Europe-EQEC 2017, Munich 29/06/17 20 S. Schiller, ACES Workshop Zürich, 29.-30. 6. 2017
Clock laser integration 0.30 FWHM = 32 Hz Excitation probability 0.25 0.20 0.15 0.10 0.05 0.00 - 200 - 100 0 100 200 Ś wierad et al., Sci. Rep. 6 , 33973 (2016) Detuning (Hz) CLEO/Europe-EQEC 2017, Munich 29/06/17 21 S. Schiller, ACES Workshop Zürich, 29.-30. 6. 2017
H2020 Characterization of the SOC breadboard demonstrator Stefano Origlia , Mysore Srinivas Pramod, Stephan Schiller ( Universität Düsseldorf ) Yeshpal Singh, Sruthi Viswam, Kai Bongs ( University of Birmingham ) Sebastian Häfner, Sofia Herbers, Sören Dörscher, Ali Al-Masoudi, Roman Schwarz, Uwe Sterr, and Christian Lisdat ( PTB Braunschweig )
I-SOC clock breadboard demonstrator: current set-up Control Reference Physics Clock laser electronics cavity package electronics 470 kg 1.1 kW, 2000 liter Laser modules S. Origlia Pramod M.S. S.Origlia et al., Proc. SPIE 9900, 990003 (2016);http://arxiv.org/abs/1603.06062
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