Gravimètre Quantique Absolu : une utilisation...
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Gravimètre Quantique Absolu : une utilisation opérationnelle des atomes froids pour la mesure de gravité Dr. Jean Lautier-Gaud Journée CNFGG
Transcript of Gravimètre Quantique Absolu : une utilisation...
GravimètreQuantiqueAbsolu:uneutilisationopérationnelledesatomes
froidspourlamesuredegravité
Dr.JeanLautier-GaudJournéeCNFGG
Outline
• Brief overview ofMuquans
• Absolutegravimetry with coldatoms
• TheAbsoluteQuantumGravimeter(AQG)
– Instrumentdescription
– Operation
• Firstresults &status
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OurcompanyFounded in 2011, Muquans delivers turnkey high-precision sensors based on quantum manipulation oflaser-cooled atoms
Muquansprovides acomplete lineofhigh-performancescientific instrumentsdedicated tometrology :
100millionofatomstemperature ofafewµK
AQG MuClock Lasersystems
Frequencytransfer links
MUQUANS: COMMERCIALLY PROVIDEOPERATIONAL AND TURNKEY HIGH-PRECISION SENSORSAND RESEARCH-GRADE LASER SYSTEMS
Technology transfers from SYRTE laboratory(Observatoire de Paris) & Institut d’Optique
Active in more than 20 countries
Team of 24 engineers, scientists, and techniciansstate-of-the-art laboratories & production lines
Core technology developed for over 15 years
Muquans is located in the Bordeaux area
Ourteamandtechnical capacities
• Muquansgathers adeep expertiseoverallthekeycompetencies :– Quantumphysics– Optics & laser– Systemengineering, opto-mechanics andultra-highvacuum– Electronics,RFandmicro-wave– Real-timesoftware,dataacquisition,andsignalprocessing
• Fully equiped laboratories andproductionlines tocontroleach step ofour activity
High-precision gravimetrywith cold-atoms
g = 9.8142627….. m/s2
Flattening
Mountains & trenches
Internal density anomalies
Large reservoirs Time variations due to tides
Big buildings
1000 µGals
Figure:OlivierdeVironIPGP
100 µGals 10 µGals 1 µGalà
Themeasurementofg• Absolutemeasurement ofg:freefall ofatestmassinvacuum.Here,testmass=ensembleoflasercooled atoms
We accurately monitorthebalistictrajectory ofthefreefalling atoms withlasers.
Measurement*sequence*
100millionofatomstemperature ofafewµK
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AQGfollowstheleadoftheCAG• ColdAtom Gravimeterdeveloped atLNE-SYRTElaboratory• State-of-the-artperformances:
• 20+peer-reviewed publications• Only atomic gravimeter toparticipatetointernationalkeycomparisons(since 2009)
Accuracy 4,3μGal
Recordsensitivity 6μGal/√Hz
Ultimate stability 0,2μGal
P.Gillot,Metrologia 51,L15-L17(2014)
Themeasurementofg• Free-fall oftheatoms is compared toastanding-wavereferenced toafixed retroreflecting mirror.
- Verticalaccelerometer- Mach-Zehnder interferometer- Stimulated Ramantransitions
Measurement*sequence*
𝜑 ∝ 𝑎. 𝑇&
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Take-homemessage1:Keyadvantages ofquantumgravimetry
• Absolute gravity measurements atthe μGal level withexcellentsensitivity, long-term stability,andaccuracy
• Continuous measurements formonths,fewHzrep.Rate
• Nomoving partsunder vacuum(reduced maintenance)
• Nomechanical nor optical alignment,noprimary pumping
• Robustness toground vibration
• Different measurement principle (metrology)
AbsoluteQuantumGravimeterofMuquans
à Instrumentdescriptionà Scientificresultsà AQGoperation
Absolute QuantumGravimeterFirstcommercialquantumgravimeter intheworld
Actual versiondedicated tocontrolled-environment13
Absolute QuantumGravimeterDegree ofmaturity ofthetechnology andlevel ofintegration
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Absolute QuantumGravimeter• Compactatomic absolute gravimeter
Performances(demonstrated):
Physicalpackage:
Sensitivity 50μGal/√HzLongtermstability 1µGal
Accuracy fewµGal
DimensionsSensorhead:h=70cm,diam=38cmLaser:100x50x70cm3
Mass 100kg(instrumentonly)
Powerconsumption 300W
Nomechanical isolationplatformNosuperspring 15
PrincipleofoperationMeasurement*sequence*
Freefall=0.12sTemperature≈1µK
Measurementcyclingfrequency:afewHzQ.Bodart,etAl.« Acoldatompyramidalgravimeterwithasinglelaserbeam » ,AppliedPhysicsLetters96,134101(2010)
KeytechnologicalaspectsofAQG
• Hollow pyramid retroreflectorà Singlelaserbeam atom interferometer(instead of6usually)
• Fiber lasertelecom technologiesà Fibered,reliable androbust lasersystem
• Activecompensationofground vibrationà Excellentimmunity tovibrationnoise(nomechanical isolation)
Immunity toground vibrations• AQGmeasures therelativeacceleration between thefree-falling atoms andthesensor head,laying onthefloor:
ameasured =g +acceleration noise(vibration)FewHzcycling frequencyà aliasingofthevibrationnoise
• Vibrationrejection:correlation with aclassicalaccelerometer
Classical accelerationsignal
AtomicsignalAQGsensor
head
Classicalaccelerometer
g
Data• TheAQG-A01hasbeenrunningforalmost 2years now
àAsitecan be properly measured within 30minutes
Demonstratedsensitivity:50μGal/√Hz
Resolution:1.5μGalwithin 30min.
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1,5months continuous data(1μGal=10-8 m/s2)
ComparisonAQGvsiGravJune2015(Larzac)
60hlongcont.meas.at2Hz
σres =2μGal
AQG
Noapparentdrift
Sensitivity inurban environment
Demonstrated sensitivity:50μGal/√Hz,1.5μGal reached in30min
• Measurements at2nd floor ofinner citybuilding(Talence,France)
4.5longcontinuous meas.at2Hz
σres =0.6μGal
Cf.Gmob
Sensitivity inurban environment• Measurements at2nd floor ofinner citybuilding(Talence,France)
Allanstandarddeviation
Sensitivity inurban environment• Measurements at2nd floor ofinner city
Allanstandarddeviation
Measurement campaign inLarzacComparison w/absolute grav.
FG5-228(N.LeMoigne,CNRS,France)
Larzac,France2015/06/12
FG5FG5
AQG
AQG
Measurement campaign inTrappesComparison w/gravimeters (S.Merlet,LNE-SYRTE,France)
Trappes,France2015/09/29
Deliveryoftheworld’s 1stcommercialatom gravimeter
DeliveryoftheAQG-01toRESIF(France) onMarch,29th2016
(N.LeMoigne &S.Bonvalot)
FG5FG5
AQG
AQG
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Take homemessage2:Keyadvantages oftheAQG
• Advantages ofquantumgravimetry
+• Compacity andmobility• Easy andquicktooperate (technician level)• Low operator dependent measurements• Greatrobustness wrt toground vibrations
àNosuperspring
Actualstatus- 01• About10tripsoutside ofMuquansfacility (even toHolland)
• Transportability,robustness,easeandquickness toset-upà validated
• AQGready tomeasure within 1h1μGal level reached within 30min(quietplace)
• Excellentrepeatability
• Continuous measurements overmonths
à AQGis operationalAQGinits boxesinacar
Actualstatus- 02• Urban sensitivity :2μGal level reached within 15min
• Improvement ofweight &volume
• 2units under production
• Metrological assessment ofbiases
à development ofthefield version
AQGinits boxesinacar
Thankyouforyourattention!
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