Gravimètre Quantique Absolu : une utilisation opérationnelle des atomes froids pour la mesure de gravité. Dr. Jean Lautier-Gaud Journée CNFGG

Transcription

1 Gravimètre Quantique Absolu : une utilisation opérationnelle des atomes froids pour la mesure de gravité Dr. Jean Lautier-Gaud Journée CNFGG

2 Outline Brief overview of Muquans Absolute gravimetry with cold atoms The Absolute Quantum Gravimeter (AQG) Instrument description Operation First results & status 2

3 Our company Founded in 2011, Muquans delivers turnkey highprecision sensors based on quantum manipulation of laser-cooled atoms 100 million of atoms temperature of a few µk Muquans provides a complete line of high-performance scientific instruments dedicated to metrology : AQG MuClock Laser systems Frequency transfer links

4 MUQUANS: COMMERCIALLY PROVIDE OPERATIONAL AND TURNKEY HIGH-PRECISION SENSORS AND RESEARCH-GRADE LASER SYSTEMS Technology transfers from SYRTE laboratory (Observatoire de Paris) & Institut d Optique Team of 24 engineers, scientists, and technicians state-of-the-art laboratories & production lines Core technology developed for over 15 years Active in more than 20 countries Muquans is located in the Bordeaux area

5 Our team and technical capacities Muquans gathers a deep expertise over all the key competencies : Quantum physics Optics & laser System engineering, opto-mechanics and ultra-high vacuum Electronics, RF and micro-wave Real-time software, data acquisition, and signal processing Fully equiped laboratories and production lines to control each step of our activity

6 High-precision gravimetry with cold-atoms

7 g = m/s 2 Flattening Figure: Olivier de Viron IPGP Internal density anomalies Mountains & trenches Large reservoirs 1000 µgals Time variations due to tides Big buildings à 100 µgals 10 µgals 1 µgal

8 The measurement of g Absolute measurement of g: free fall of a test mass in vacuum. Here, test mass = ensemble of laser cooled atoms We accurately monitor the balistic trajectory of the free falling atoms with lasers. 100 million of atoms temperature of a few µk 8

9 AQG follows the lead of the CAG Cold Atom Gravimeter developed at LNE-SYRTE laboratory State-of-the-art performances : Accuracy Record sensitivity Ultimate stability 4,3 μgal 6 μgal/ Hz 0,2 μgal P. Gillot, Metrologia 51, L15-L17 (2014) 20+ peer-reviewed publications Only atomic gravimeter to participate to international key comparisons (since 2009)

10 The measurement of g Free-fall of the atoms is compared to a standing-wave referenced to a fixed retroreflecting mirror. - Vertical accelerometer - Mach-Zehnder interferometer - Stimulated Raman transitions φ a. T &

11 Take-home message 1: Key advantages of quantum gravimetry Absolute gravity measurements at the μgal level with excellent sensitivity, long-term stability, and accuracy Continuous measurements for months, few Hz rep. Rate No moving parts under vacuum (reduced maintenance) No mechanical nor optical alignment, no primary pumping Robustness to ground vibration Different measurement principle (metrology) 11

12 Absolute Quantum Gravimeter of Muquans à Instrument description à Scientific results à AQG operation

13 Absolute Quantum Gravimeter First commercial quantum gravimeter in the world Actual version dedicated to controlled-environment 13

14 Absolute Quantum Gravimeter Degree of maturity of the technology and level of integration 14

15 Absolute Quantum Gravimeter Compact atomic absolute gravimeter Performances (demonstrated): Sensitivity Longterm stability Accuracy 50 μgal/ Hz 1 µgal few µgal Physical package: Dimensions Mass Sensor head: h = 70 cm, diam = 38 cm Laser : 100 x 50 x 70 cm3 100 kg (instrument only) Power consumption 300 W No mechanical isolation platform 15 No superspring

16 Principle of operation Temperature 1 µk Free fall = 0.12 s Measurement cycling frequency: a few Hz Q. Bodart, et Al. «A cold atom pyramidal gravimeter with a single laser beam», Applied Physics Letters 96, (2010)

17 Key technological aspects of AQG Hollow pyramid retroreflector à Single laser beam atom interferometer (instead of 6 usually) Fiber laser telecom technologies à Fibered, reliable and robust laser system Active compensation of ground vibration à Excellent immunity to vibration noise (no mechanical isolation)

18 Immunity to ground vibrations AQG measures the relative acceleration between the free-falling atoms and the sensor head, laying on the floor: a measured = g + acceleration noise (vibration) Few Hz cycling frequency à aliasing of the vibration noise Vibration rejection : correlation with a classical accelerometer Classical accelerometer AQG sensor head Classical acceleration signal Atomic signal g

19 Data The AQG-A01 has been running for almost 2 years now 1,5 months continuous data (1 μgal = 10-8 m/s 2 ) Demonstrated sensitivity: 50 μgal/ Hz Resolution: 1.5 μgal within 30 min. àa site can be properly measured within 30 minutes 19

20 Comparison AQG vs igrav June 2015 (Larzac) AQG 60h long cont. meas. at 2 Hz σ res = 2 μgal No apparent drift

21 Sensitivity in urban environment Measurements at 2 nd floor of inner city building (Talence, France) 4.5 long continuous meas. at 2 Hz Cf. Gmob σ res = 0.6 μgal Demonstrated sensitivity: 50 μgal/ Hz, 1.5 μgal reached in 30 min

22 Sensitivity in urban environment Measurements at 2 nd floor of inner city building (Talence, France) Allan standard deviation

23 Sensitivity in urban environment Measurements at 2 nd floor of inner city Allan standard deviation

24 Measurement campaign in Larzac Comparison w/ absolute grav. FG5-228 (N. Le Moigne, CNRS, France) Larzac, France 2015/06/12 AQG FG5 FG5 AQG

25 Measurement campaign in Trappes Comparison w/ gravimeters (S. Merlet, LNE-SYRTE, France) Trappes, France 2015/09/29

26 Delivery of the world s 1st commercial atom gravimeter Delivery of the AQG-01 to RESIF (France) on March, 29th 2016 (N. Le Moigne & S. Bonvalot) AQG FG5 FG5 AQG

27 Take home message 2 : Key advantages of the AQG Advantages of quantum gravimetry Compacity and mobility + Easy and quick to operate (technician level) Low operator dependent measurements Great robustness wrt to ground vibrations àno superspring 27

28 Actual status - 01 About 10 trips outside of Muquans facility (even to Holland) Transportability, robustness, ease and quickness to set-up à validated AQG ready to measure within 1h 1 μgal level reached within 30 min (quiet place) Excellent repeatability Continuous measurements over months à AQG is operational AQG in its boxes in a car

29 Actual status - 02 Urban sensitivity : 2 μgal level reached within 15 min Improvement of weight & volume 2 units under production Metrological assessment of biases à development of the field version AQG in its boxes in a car

30 Thank you for your attention! See you at EGU booth # 103 VISIT CONTACT jean.lautier@muquans.com FOLLOW US ON LINKEDIN