Exploring the Potential of Ultra Cold Gases for Fundamental Tests in Space Wolfgang Ertmer Gottfried Wilhelm Leibniz Universität Hannover Institute for Quantum Optics (IQ) Centre for Quantum Engineering and Space-Time Research (QUEST) Laser Centre Hannover (LZH)
Extended free fall Advantages in space
Novel optical clocks QUEST - Centre for Quantum Engineering and Space-Time Research
Progress in Quantum Sensor Cold Atom Inertial Sensors
Overview (Part II) Fundamental quests for modern physics Atomic quantum sensors for space Proposals for fundamental tests in space Ultra cold gases in micro gravity (µ g) First experiments towards space missions QUANTUS: FirstBEC in micro gravity
Fundamental Physics Tests in Space FUNDAMENTAL QUESTS FOR MODERN PHYSICS
Quests of Modern Physics Understanding of the quantum world Non locality, quantum realism, Copenhagen interpretation (Niels Bohr) Entanglement Superposition, decoherence Cosmology Origin of the Universe Nt f d k tt d d k Nature of dark matter and dark energy,... Quantum... Gravity
Space as Laboratory Large velocity differences Large gravitational potential differences Unsurpassed long distances Ultra low noise environment "Infinitely" long freefall fall EXTENDED PARAMETER RANGE
Fundamental Physics Tests in Space (1) Space-time and Gravitation (GR) Preferred ee ed frame? Lense Thirring effect Detection of gravitational waves
Gravitational wave detectors E.g. GEO 600 Detector near Hanover: arm length: 600 m Frequency range: 50 Hz... 2 khz State of the art suspensions used in GEO 600 600 m Arial view of the Geo 600 site geo600.aei.mpg.de
LISA (Laser Interferometer Space Antenna) Giant Michelson hl interferometer composed of three satellites Arm length 5 Mill. km Frequency range: 0,1 mhz... 1 Hz Artists impression of LISA satellites lisa.nasa.gov Stebbins, Class. Quantum Grav. 25 (2008) 114050
Fundamental Physics tests in space (2) Foundation of quantum mechanics Matter-wave interferometry on the crossover between the classical and quantum world EPR-type experiments over long distances and unperturbed by environmental and gravitational disturbances Vision: Testing entanglement over very long distances and with macroscopic bodies
Fundamental Physics Tests in Space (3) Quantum gravity Exploration of matter wave decoherence caused by space time fluctuations Testing the equivalence principle by free falling quantum probes (distinct atomic species) (Proposed <... 10-17, tested @ 10-13 ) Investigation i the time variance of fundamental constants Fine structure re α (drift (tested) < 10-17 /a) Gravitation G ( drift (tested) < 10-13 /a)
Example: Space-time fluctuations QUEST - Centre for Quantum Engineering and Space-Time Research Induce apparent violation of the equivalence principle, testable with atomic interferometry (E. Göklü & C. Lämmerzahl, Class. Quantum Grav. 25, 105012 (2008)) Different bodies feel fluctuations ti differently Induce apparent decoherence in atomic systems, but long decoherence time for single particle states fl t ti (H. P. Breuer, E. Göklü & C. Lämmerzahl, submitted) fluctuations lead to decoherence
Example: Principle of Equivalence Differential measurements between different isotopes Current classical limit: 3 x 10 13 (PRL 83, 3585, [1999], Torsion balance) Equivalence Principle General Relativity Gravity
Atomic clocks Atomic inertial sensors Degenerate quantum gases ATOMIC QUANTUM SENSORS FOR SPACE
Benefits of extended free fall & µ-gravity For inertial i atomic quantum sensors and atomic clocks,... : Extended Time of Evolution + Perturbation-free Evolution + Must not compensate gravity / levitate the atoms
Optical Atomic Clocks Now better than primary Caesium standard d Promise 10-18... Pre-stabilise laser to cavity Post-stabilise to cold atomic reference
Benefits of µ gravity environment Extended Time of Evolution Inertial Quantum Sensors Rotational Phase shift Δϕ rot = 2m Atom h r Accelerational Phase shift Δϕ acc = T 2 r k r a r Ω r Ω A T 2 r a Sagnac Interferometer
Gyroscope Δ ϕ rot = 2m Atom h r A Ω r 8 Rotational Sensitivity with 10 8 atoms: Ground 10-9 rad/ Hz @ Expansion Time 0.025 s Space 8 10-12 rad/ Hz @ Expansion Time 3 s Earth rotation rate:7.2 10-5 rad/s
Accelerometer Δ ϕ acc = T 2 r k a r Acceleration Sensitivity with 10 8 atoms: Ground 10-10 g/ Hz @ Expansion Time 0.2 s Space 10-12 g/ Hz @ Expansion Time 3 s
HYPER MICROSCOPE MXWG SAGAS PROPOSALS FOR FUNDAMENTAL TESTS IN SPACE
Lense-Thirring effect Predicted by J.Lense and H.Thirring (1918) Rotating Mass creates a gravitomagnetic Field Test mass begins to rotate with Ω LT relative to the Inertial system of the stars. Gravito magnetic i field lines Gravity Probe B
Measuring the Lense-Thirring effect with an Atom interferometer: Gravito-magnetic effect causes additional contribution to rotation additional Sagnac Phase: Problem: Beam splitters must be connected to distant inertial frame Satellite connected to a guide star with telescope Measuring local rotation (atomic trajectories) in a fixed inertial frame
HYPER Mapping the Lense Thirring Effect close to the Earth Ω Improving the knowledge of the Fine structure constant Δω~h/m Atomic Gyroscope controls a satellite Differential measurement between two atomic gyroscopes and a star Tracker orbiting the Earth Testing the EP with microscopic bodies
Details of satellite Weight < 1000 kg Sun Synchronous, polar orbit Altitude 1000 km Power ~ 500 W Dimensions 1.5 x 1.5 x 1 m 2 Drag Free Sensors Precision Star Tracker pointing in Anti sun direction towards guide stars accuracy 10 8 rad (10 Hz sampling) 2 Precision i Atomic Rotation ti Sensors
Hyper-Design Launch of 10 9 at @ 1µK with 20 cm/s, 2T Drift = 3 s Lenght: 60 cm 2 Atomic Sagnac units (orthogonal) Sensitive for rotation und acceleration in two spatial directions. Optical axis of the telescope connected with the optical bench. Sensitive ii axes orthogonal to telescope axis.
Lense-Thirring effect / HYPER Ω x sin 2 θ y cos 2θ + 1 Ω LT 3 y x Simulated signal of both ASU (Atomic Sagnac Units): Ω θ Target accuracy (p.a.): 3 10 At pole: +1.25 x 10 14 rad/s At equator: 2.5 x 10 14 rad/s 16 spatially monitoring LT effect rad / s around the earth
MICROSCOPE QUEST - Centre for Quantum Engineering and Space-Time Research Aiming to test the EP to an accuracy of at least 10 15 To be launched in 2010 free falling proof masses guiding the satellite (laboratory system) Read out of distance or relative motion by optical means capacitive measurements 3 10 3 10 10 11 g 2 1 @ 10 Hz g @10 Hz 4 10 10 1 Hz Hz magnetometers
Pioneer anomaly The two way Doppler residuals for Pioneer 10 vs time [1 Hz is equal to 65 mm/s range change per second]. (8.74 ± 1.33) 10 10 m/s 2 PRD, 65, 082004 (2002)
SAGAS 1. Cold atom absolute accelerometer, 3 axis measurement of local acceleration. Uncertainty 5 10 12 m/s 2 (@ 10 days) 2. Optical atomic clock with an uncertainty 10 17 in relative frequency for (@ 10 days) 3. Laser ranging and/or Doppler for navigation and two way time/frequency transfer, with frequency stability 10 17 (@ 10 days), and ranging or Doppler uncertainty tit 10 ns (3 m) or 10 15 (3 x 10 7 m/s) Range = up + down Synchro = up down
Matter Wave Explorer of Gravity Comparing the free fall of e.g. Cesium with Rubidium atoms in Earth orbit Determining the acceleration by measuring the phase shift:
MWXG first quantum test the Equivalence Principle with spin polarized particles Necessary conditions: Both atomic species in one MOT (same centre of gravity) Simultaneous execution of experiments Simultaneous detection of both atomic species Favourable candidates Rb, K Target accuracy:
Activities within Europe LISA PHARAO & ACES QUANTUS (DLR) ICE (FRANCE) ESA 4477 MAP: Atom Interferometry ATOMIC GRACE MWXG SAGAS Atom Quantum Sensors on ground and in space
Degenerate quantum gases in µ g ULTRACOLD GASES IN MICRO-GRAVITATION
Degenerate quantum gases in µ-g Atomic sensors & fundamental tests Inertial standards (drag-free sensors) Tests of the equivalence principle Relativistic effects
Degenerate quantum gases in µ-g Low temperature physics @ femto Kelvin Lower temperature regimes Spinor-dynamics & correlations Thermodynamics of fermionic and bosonic mixtures and ideal systems Sub-healing length physics
Slowing free expansion tim me Conversion of interaction energy to kinetic energy Rd Reducing density bf before release by lowering trap depth (frequency) Regime of asymptotic aspect ratio BEC BEC
Shallow traps Require low trap frequencies On ground On ground: Trap too shallow to levitate atoms (trap frequencies < 30 Hz) g Control of trap dynamics & release
Degenerate quantum gases in µ-g Atom lasers & atom optics (De-)Coherence Evolution of BEC Atom laser limitations Quantum deflection
FINAQS ATLAS QUANTUS FIRST EXPERIMENTS TOWARDS SPACE MISSIONS
FINAQS Comparison of distinct topologies Compact and transportable device Non classical sources: BEC / Squeezed Atoms Comparison between atomic gyroscopes Hybrid gyroscope: Laser/Atom gyroscope
ATLAS: All-optical source for ultra-cold matter Rigid Source for Interferometry Testing the principle i of equivalence 40,41 K 85,87 Rb Towards Heisenberg limited interferometry Holder for glass cell and 2D- MOT coils and mount for telescopes Glass cell Rb and K dispensers Titanium sublimation pumps Ion pumps Laser light for MOT Laser light for dipole trap MOT coils 50 cm
QUANTUS Preliminary studies of Bose Einstein condensates in microgravity Collaboration of the Universities iti of Hamburg, Bremen (ZARM), HU Berlin, Ulm, MPQ Munich, and LUH Hanover
Platforms of µ-gravitation platform µg quality [g] µg duration drop tower 10 6 4.8 s, x 2 with catapult ISS 10 4 days to months space carrier 10 6 3 days parabola flights 10 2 20 seconds ballistic rockets 10 5 6 minutes
Drop Tower Conditions & Requirements Free Fall: up to 4.5 s (catapult 9s) Duration > 1 BEC Experiment 3 flights per day Test of a robust BEC Facilities 50 Dimensions < 0.6 x 1.5 m < 234 kg Height 110 m 40 30 20 10 -Beschleunigun ng [g] z- 0 0 2000 4000 6000 8000 Zeit [ms]
Droptower (Catapult mode) Increase of the free fall time to 9 sec Forces up to 30 g at the launch of the experiment Animation Realfilm Kinematik 47
Atom chip-based experiment
Experimental setup Experiment can be driven completely by battery Low Noise current drivers for Atom chip Completely remote controlled Smallest Laser design due to space limitationsit ti 87 Rb
Route to BEC ( 87 Rb) 1. External MOT 2. Chip MOT 3. Shifting of the MOT 4. Optical molasses 5. Optical pumping 6. Trapping in IP trap 7. Evaporation 8. Analysis of the BEC 50
Loading gprocedure Atom number: 1,3 x 10 7 Temperature: ~230 µk MOT loading time: 10 seconds Atom number: 1,2 x 10 7 Temperature: ~230 µk Shifting of the MOT in 30 ms Atom number: 1,0 10x 10 7 Temperature: 23 µk after optical molasses Atom number: 5 x 10 6 Temperature: 38 50 µk after loading Magnetic compression in 200 ms 51
First BEC in microgravity First BEC on November 06th, 2007 More details on 16mstimeofflight flight chosen for analysis reasons 7500 atoms in the condensate Clear proof of bimodal distribution 430 µm BEC in microgravity 170 drops realized up to now! in the next Talk!
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Conclusion Quantum engineering: i an innovative i versatile tool for Fundamental Physics tests in space Degenerate quantum gases: essential iltool for quantum technology, quantum standards, and quantum metrology Rapidly evolving from laboratory demonstrators to tools for Fundamental Physics in µ g Technology readiness for upcoming missions
Hanover greetings QUEST - Centre for Quantum Engineering and Space-Time Research
Post Doc Positions PhD Positions open ENOUGH SPACE FOR EXCITING EXPERIMENTS
Thank you for your attention Wolfgang Ertmer for the QUANTUS Team Institute for Quantum Optic (IQ) Centre for Quantum Engineering and Space-Time Research (QUEST) Laser Centre Hannover (LZH)