Proposal for a Gravity Explorer Satellite Proposal for a Gravity - PowerPoint PPT Presentation

Workshop on Workshop on "ADVANCES IN PRECISION TESTS AND EXPERIMENTAL GRAVITATION IN SPACE" "ADVANCES IN PRECISION TESTS AND EXPERIMENTAL GRAVITATION IN SPA CE" Arcetri, September 28 , September 28- -30, 2006 30, 2006 Arcetri Proposal for a Gravity Explorer Satellite Proposal for a Gravity Explorer Satellite Mission Mission S. Schiller, A. Gö örlitz, J. Koelemeij, B. Roth, A. Nevsky, A. Wicht, rlitz, J. Koelemeij, B. Roth, A. Nevsky, A. Wicht, U. D U. Dü üsseldorf sseldorf S. Schiller, A. G G.Tino, N. Poli, R.E. Drullinger, , N. Poli, R.E. Drullinger, U. Firenze/LENS, U. Firenze/LENS, G.Tino P. Lemonde, LNE LNE- -SYRTE Paris SYRTE Paris P. Lemonde, U. Sterr Sterr, F. Riehle, E. , F. Riehle, E. Peik Peik, C. Tamm, , C. Tamm, PTB Braunschweig PTB Braunschweig U. C. Salomon, ENS Paris, ENS Paris, C. Salomon, P. Gill, H. Klein, H. Margolis Margolis NPL NPL Teddington Teddington P. Gill, H. Klein, H. G. Mileti , Obs. Neuchatel, , Obs. Neuchatel, G. Mileti R. Holzwarth, T. H Hä änsch nsch, , MPQ MPQ Munich Munich R. Holzwarth, T. E. Rasel, W. Ertmer , U. Hannover , U. Hannover E. Rasel, W. Ertmer H. Dittus, C. Lä ämmerzahl, mmerzahl, ZARM Bremen, ZARM Bremen, A. Peters, A. Peters, H.U. Berlin H.U. Berlin H. Dittus, C. L E. Samain Obs. Cote Obs. Cote d d‘ ‘Azur Azur , L. Iorio , L. Iorio U. Bari, U. Bari, I. Ciufolini I. Ciufolini U. U. Lecce Lecce E. Samain

Contents � Overview � Choice of optical clock types � Some implementation considerations � Progress on clocks and related topics in Düsseldorf

Introduction Scope of a satellite m ission: - Explore Gravity: � Fundamental physics: - high precision test of fundamental aspects of General Relativity - search for new physics � Geophysics: Gravity field and elevation mapping - Clock comparison measures the difference in U - Map out U using movable clocks - Time and frequency distribution on earth and in space („Master clock“): � Terrestrial use of future optical clocks requires a Clock reference clock in a well-defined potential ensemble ∆ U/ U = 1 . 10 -9 (corresponds to ∆ h = 1 cm) results in ∆ν/ν = 1 . 10 -18 � Precision navigation in space � Space-VLBI - Optical Link between distant clocks � Optical Clocks & Optical Metrology

Mission Scenario � Orbital phase I (~ 1 year duration, Clock ensemble highly elliptic orbit) ν 1 ν 2 ν 0 - Test of Local Position Invariance and of grav. redshift � Orbital phase II (geostationary, several years duration) - Master clock Clock ensemble for earth and space ν 1 ν 2 users - Geophysics

Optical Clocks 10 -9 10 -10 Optical Optical Clocks Clocks 10 -11 10 -12 Relative Uncertainty Microwave Microwave clocks clocks 10 -13 10 -14 , Ca Yb + Mikrowave clocks clocks: ~ 9 GHz : ~ 9 GHz Mikrowave 10 -15 Cs fountains Sr Optical clocks clocks: ~ 400 000 GHz : ~ 400 000 GHz Optical Yb + 10 -16 Hg + Al + 10 -17 1 0 - 1 8 10 -18 1950 1960 1970 1980 1990 2000 2010 Year Review: P. Gill, Metrologia (2005)

Measurement of the Gravitational Redshift ∆ ν ∆ U = ζ + i U ... ν i 2 c 0 Clock ensemble ν 1 ν 2 2 . 10 -10 ν 0 for eccentricty ε = 0.4 � - Absolute gravitational redshift measurement - Test of higher-order relativistic corrections (Linet & Teyssandier 2002, Blanchet et al 2001, Ashby 1998) - Comparison with a ground clock (via microwave/optical link) - Requires precise orbit determination (laser ranging) � - Gravitational redshift universality test: ζ 1 = ζ 2 ? ( Test of Local Position Invariance) - Intercomparison of dissimilar on-board clocks

Gravity and its foundations Gravitational redshift General Relativity Lense-Thirring effect .... Metric theory of gravity Einstein Equivalence Principle Local Position Universality of Local Lorentz Invariance Free Fall Invariance (Universality of grav. Redshift (Weak equivalence princip.) (Special Relativity) constancy of constants)

Fundamental Constants and Clocks � Frequencies depend on fundamental constants ν = ν α ( , m m , , g ,...) i i e N N � Gravitational redshift experiments test whether some of these constants β j depend on the gravitational potential ⎛ ⎞⎛ ⎞ β − ∆ ν ∑ d β = β ⇒ ζ = + ν 1 ⎜ ⎟⎜ j ( U )? 1 i ⎟ j j i ⎝ ⎠ i ∆ β ⎝ ⎠ 2 d U c ( ) j j � The clock ensemble used for tests of LPI should contain clocks whose frequencies depend „strongly“ on the fundamental constants

Fundamental Constants � Some constants can be related to more fundamental constants: ∝ Λ + m corrections Strong interaction p QCD ∝ φ = m Higgs vacuum field Weak interaction e ∆ ∆ φ Λ ( m m ) ( ) − = ∆ α α + N p QCD 3 ฀ c , c O (10 ) c ( ) c : α φ α φ φ Λ m m N p QCD ∆ Λ ∆ Λ ∆ ( m ) ( m ) g = − + − q QCD s QCD 1 2 N (10 ) (10 ) O O Λ Λ g m m N q QCD s QCD Flambaum and Tedesco 2006

Optical Clocks and Fundamental Constants � Scaling of transition energies (in units of Rydberg energy) ( ) ( ) ∆ ν ν ∆ α α ˆ ˆ ( α � Electronic energies (incl. relativistic effects) G ) Yb: 0.31 Sr: 0.06 Yb + : (0.9, - 5.3) m m � Vibrational energies in molecules e N e.g. Hilico et al. 2000, S.S. and Korobov 2005 m ( ) α 3 e � Hyperfine transition in hydrogenlike highly charged ions Z g F N m (S.S., TCP 2006) p ( ) ( ) ⎛ ⎞ ∆ Λ ∆ Λ ∆ ν ∆ α m / m / � Nuclear transition ⎜ ⎟ = + q QCD − s QCD 5 O (10 ) 4 10 ⎜ ⎟ ν α Λ Λ (Peik and Tamm 2003, m / m / ⎝ ⎠ q QCD s QCD Flambaum 2006)

Clock choice � A comparison of an atomic optical clock to a molecular optical clock is (within the Standard Model) sensitive to several fundamental constants: ∆ Λ ∆ ν ν ∆ α ( m ) ( ) = + + e QCD at vib O (1) O (1) ν ν α Λ m at vib e QCD ∆ Λ ∆ Λ ( m ) ( m ) − + − q QCD s QCD 1 2 O (10 ) O (10 ) Λ Λ m m q QCD s QCD In gauge unification theories the time variations of α and m e / Λ QCD are correlated � (Damour 1999, Langacker et al, Calmet & Fritzsch, 2002) ∂ Λ ∂ α ( m / ) t e QCD ฀ t 40 ~ Λ α / m e QCD � Optimum clock choice may be different for the two proposed applications: - For LPI test and redshift measurement, stability on timescale of ~ 10 h is relevant - For Master Clock use, accuracy and long-term stability are also important

Ultracold Molecule Clocks Proposals: U. Fröhlich et al. Lect. N. Phys. 648 , 297 (2004) S.S. and V. Korobov, PRA 71 , 032505 (2005) � For precision spectroscopy, ultracold, trapped molecules are necessary - reduces various line broadening mechanisms - allows best control over and characterization of systematic effects � Rapid progress of the field (e.g. Special Issue J. Phys. B 2006) - Ultracold neutral diatomic molecules produced by photoassociation from ultracold atoms - Trapping in an optical lattice demonstrated (e.g. Rom et al. 2004) - Molecular ions have been cooled and trapped by sympathetic cooling (Aarhus/Düsseldorf) - Cold Neutral dipolar molecules have been trapped in electric/magnetic traps (Rhinhuizen/Berlin/München/Boulder) � Cold molecular clock performance could reach levels similar to atomic clocks - Their development will profit from optical atomic clock developments

Quantum logic ion clocks P. Schmidt et al. (2005) � Uses a laser-coolable „logic“ ion and a „clock“ ion, a few µm apart � Clock ion is sympathetically cooled � No laser cooling of clock ion is required, therefore greatly extends variety of usable clock ions � Spectroscopy uses coherence - no fluorescence of clock ion occurs � Should be applicable to molecular ions as well Clock ion RF trap structure Clock laser Logic ion Logic laser NIST Be + / Al + clock status (TCP 2006) 2.3 . 10 -17 Inaccuracy: 7 . 10 -15 τ -1/2 (1 < τ < 10 4 s) Instability: NIST

A multispecies ion trap clock for a satellite experiment � Double/ Triple ion trap clock Atomic Atomic clock ion ion clock Atomic Molecular clock ion clock ion Multi-trap structure Logic ion � Suitable logic ions: Be + , Mg + , Yb + , Ca + e.g. Al + , Yb + , suitable molecular ions � Clock ions: � Ion trap technology will be pushed strongly by quantum computing applications NIST

Satellite payload concept Cavity-stabilized narrow-linewidth Master Cavity master laser laser Frequency comb Cooling/ Clock lasers Trapping Lasers Frequency Transfer Atomic and Molecular Clocks to Earth or Space