Mission I-SOC: An optical clock on the ISS

Transcription

1 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

2 When ACES was proposed in 1997 Prelude 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 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)

3 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 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,

4 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 Space frequency comb (SFC) 10 GHz Optical cavity + laser ( clock laser, OSRC) Upgraded ELT (ELT+) Space lattice clock (SLOC) Laser bench 429 THz

5 ACES and I-SOC ACES actual/estimated performance vs. I-SOC requirements ACES I-SOC * Improvem. Clock instability 1x10-13 / 1/2 8 x / 1/2 (up to s) x 100 Clock inaccuracy 1x x10-17 x 10 MWL / MWL+ 1.5 ps ( / s) 1/ ps ** x 1 day ELT / ELT s s 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 ground clock comparisons (or ground-space) I-SOC performance can be tested fully on the ground (trapped atoms) * from I-SOC ESR document ** ground-to-space

6 Consequences of I-SOC performance Higher stability of ELT+ and MWL both allow clock comparisons at 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

7 Heritage from ACES Ground stations (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!

8 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 Optical lattice clock (SLOC) inaccuracy: <1 x ; instability: <1 x / 1/2 mass < 100 kg, power consumption < 250 W, volume < 0.5 m 3 MWL: ELT+: SFC: Data analysis: current ESA study (SYRTE, DLR, Timetech) Ivan Prochazka s talk M. Lezius talk P. Wolf s talk

9 SOC breadboard demonstrator development ( ) Reference cavity Clock laser breadboard Atomic unit

10 Laser cooling and trapping Sr Blue MOT (461 nm) Red MOT (689 nm) Optical lattice (813 nm) 10 3 atoms T=1.3 μk = 6.5 s T=3mK atoms T<2μK atoms z z I I x I y x I y 10

11 Modular laser system 461 nm 461 nm distribution 813 nm lattice Repumper 679 nm Repumper 707 nm 698 nm clock laser Reference cavity 689 nm cooling 689 nm stirring 461, 689, 813 nm stabilization unit 11

12 Modular laser system 461 nm 461 nm distribution 813 nm lattice Repumper 679 nm Repumper 707 nm 698 nm clock laser Reference cavity Relies on robust, mostly COTS, laser technology 689 nm cooling 689 nm stirring Units are exchangeable with improved ones 461, 689, 813 nm stabilization unit Bongs, K. et al., Development of a strontium optical lattice clock for the SOC mission on the ISS, C. R. Phys. 16, 553 (2015) 12

13 SOC: compact atomics package 13

14 SOC: compact atomics package Low power (20 W) atomic oven 1 1 M. Schioppo et al., Rev. Sci. Instrum. 83, (2012) 14

15 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, (2012) 2 I. R. Hill et al., J. Phys. B 47, (2014) 15

16 SOC: compact atomics package Vacuum chamber Low power (20 W) atomic oven 1 Permanent-magnets Zeeman slower 2 1 M. Schioppo et al., Rev. Sci. Instrum. 83, (2012) 2 I. R. Hill et al., J. Phys. B 47, (2014) 16

17 SOC: compact atomics package Vacuum chamber Low power (20 W) atomic oven 1 Permanent-magnets Zeeman slower 2 Small coils (5 W, no water cooling) 1 M. Schioppo et al., Rev. Sci. Instrum. 83, (2012) 2 I. R. Hill et al., J. Phys. B 47, (2014) 17

18 SOC: compact atomics package Temperature stabilization system (goal T<100 mk) Vacuum chamber Low power (20 W) atomic oven 1 Permanent-magnets Zeeman slower 2 TECs (5W) + Heat pipes Small coils (5 W, no water cooling) 1 M. Schioppo et al., Rev. Sci. Instrum. 83, (2012) 2 I. R. Hill et al., J. Phys. B 47, (2014) 18

19 Atomic package transport (June 2015) Birmingham Eurotunnel Braunschweig (PTB) 19

20 Clock laser integration Świerad et al., Sci. Rep. 6, (2016) 20

21 Clock laser integration Excitation probability 0.30 FWHM = 32 Hz Detuning (Hz) Świerad et al., Sci. Rep. 6, (2016) 21

22 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)

23 I-SOC clock breadboard demonstrator: current set-up Control electronics Physics package Reference cavity Clock laser electronics 470 kg 1.1 kw, 2000 liter Laser modules S. Origlia Pramod M.S. S.Origlia et al., Proc. SPIE 9900, (2016);

24 88 Sr (boson) vs. 87 Sr (fermion) 88 Sr Isotope shift: fundamental physics test (e.g. atomic 87 Sr Higgs force 1 ) Isotopic aboundance: 83% Isotopic aboundance: 7% Laser cooling easier Shorter cycle time (2 interrogations) Insensitive to vector and tensor light shift Need for magnetically induced spectroscopy: 1) Large magnetic field 2) Large clock laser beam intensity S-wave collisions May have advantages in terms of simplicity and for transportability Nuclear spin (I = 9/2): laser cooling more complicated (1 more laser) 1 st order Zeeman shift (4 interrogations) Sensitive to vector and tensor light shift Hyperfine interaction allows 1 S 0-3 P 0 transition Only p-wave collisions Better for accuracy 1 C. Delaunay et al., arxiv:

25 Clock transition line in 88 Sr (698 nm) 0.8 Collisional broadening (lineshape vs. number of atoms) 0.6 Excitation probability a.u. 8a.u. 16 a.u. 24 a.u. 36 a.u. Excitation probability FWHM = 220 = 220 mhz mhz Frequency detuning (Hz) Control of collisional broadening 3 : use << 1 atom per lattice site Long interrogation time: 4 s (Fourier-limited linewidth) 1 D. G. Matei et al., J. Phys. Conf. Ser., 723, (2016) 2 D. G. Matei et al., arxiv: Ch. Lisdat et al., PRL 103, (2009) Detuning (Hz) With stationary cavity 1,2 (PTB)

26 Clock instability SOC clock locked continuously to atoms for 74 hours Instability determined by comparison with 87 Sr clock at PTB 1,2 Combined instability of the two clocks: / Lowest instability: at = s I-SOC goal specification: / Tot. averaging time: s 1 S. Falke et al., New J. Phys. 16, (2014) 2 A. Al-Masoudi et al., Phys. Rev. A 92, (2015)

27 Preliminary uncertainty budget Effect Correction Uncertainty BBR chamber BBR oven 0 0 Scalar lattice shift 0 <10 PRELIMINARY Collisional shift Probe light shift <5 2 nd -order Zeeman shift <10 DC Stark shift 0 <2 Total <15 ν( 88 Sr) ν( 87 Sr) = (65) Hz Expect to improve soon to low level Recently published values: ν( 88 Sr) ν( 87 Sr) = (10) Hz 1 ν( 88 Sr) ν( 87 Sr) = (1.9) Hz 2 1 T. Takano, et al., Appl. Phys. Express 10, (2017) 2 C. Radzewicz, et al., Phys. Scr. 91, (2016) 31

28 Summary - I Transportable cold-atom lattice clock apparatus (2 racks, 1.1 kw) Successful transport from Birmingham (UK) to Braunschweig (D) Ultra-narrow clock transition in 88 Sr observed: 220 mhz width Excitation probability Detuning (Hz) Ultra-low instability bosonic clock: < / and at s Preliminary uncertainty: System concept is suitable for space clock Soon: low level inaccuracy; 87 Sr Total deviation, σ TOT (τ) Averaging time, τ (s)

29 Summary - II I-SOC breadboard demonstrator is a testbed for new laser units I-SOC breadboard will be developed further to become a transportable highperformance clock during the ACES mission I-SOC is technically feasible I-SOC is a test bed for quantum sensors, future clocks and links: Europe has the chance to remain at the forefront quantum technology in space and its applications I-SOC is strategic - will generate new research opportunities for a world-wide community of scientists across fields - will introduce a new technology step - future clocks will be based on its technology (upgrade/downgrade of performance can be traded off with mass, power, volume) - is part of a long roadmap of quantum technology in space (10 x improvements in accuracy, lifetime, distance ea. 10 years) S. Schiller, ACES Workshop Zürich,

30 I-SOC: way forward New approach by ESA: Science team is strongly involved in all phases of mission development 1) ESA technology developments : nm, 689 nm lasers [Fraunhofer UK, TopGaN,CNR,HHU] - CCU: laser frequency stabilization system [NPL UK, PTB] nm lattice laser [Fraunhofer UK, SYRTE] - Clock laser reference cavity (698 nm) [Airbus F hafen, NPL, SpaceTech, PTB] - Two-way microwave link [Timetech,DLR Oberpf.,SYRTE] 2) Experiment Science Document 2/2017 [Science team] 3) Phase-A study, scientific part 2017 [Science team] 4) Phase-A study, industrial part 2018 [space industry, Science team] 5) Phases B, C [space industry, Science team] Mission S. Schiller, ACES Workshop Zürich,