LP2N

Institut d’Optique d’Aquitaine

33400 TALENCE.

NAVISP-El1-013: Quantum-based sensing for

PNT

Final Presentation

Baptiste Battelier, Simon Templier, Pierrick Cheiney, Brynle Barrett,

Philippe Bouyer, Henri Porte and Fabien Napolitano

✓ Context: Quantum sensors for navigation

✓ Design of the three-axis quantum accelerometer

✓ Hybridization with classical accelerometers

✓ Performances of the mobile three axis hybrid

accelerometer

✓ Future developments

OUTLINE

2

QUANTUM SENSORS: COLD ATOM INTERFEROMETERS

3

• Cold atoms (T~µK) are free-falling under vacuum.

• Acceleration is measured by imprinting the phase of a laser on the atomic

wavepackets at 3 different times.

COLD ATOM SENSORS: STATE OF THE ART

4

Noise (𝑛𝑔/

𝐻𝑧)

Stability (ng)

AO sense 700 10

µquans 46 1 (10 ng accuracy)

Humboldt University

9.8 4

Berkeley University

37 40

SYRTE 6 2

Zhejiang University

300 60

➢Cold atom gravimeters

➢Long term stability, high accuracy

➢Commercial

➢Single vertical axis, “static” measurement

✓ Mobile cold atom interferometers

➫ONERA: Gyrostabilised onboard a boat and a plane

➫ ICE: microgravity (parabolic flights) to prepare Space missions

COLD ATOM SENSORS: STATE OF THE ART (2)

5

INERTIAL NAVIGATION

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• Land and sea mapping

• Space

• Geophysics survey

• Defense

• Autonomous vehicle

Applications

Advantages

• Autonomous system

• Higher resolution than GNSS

• Orientation and velocity information

STRAPDOWN INERTIAL NAVIGATION

7

accelerometers

∫

Project on

reference

frame

Correct for

gravity ∫ ∫

gyroscopes

orientation

velocity

Position

Aiding sensors: GPS,

magnetometers, Doppler..

• Autonomous and quiet

Cold atoms

✓ Cold atoms: high sensitivity, high accuracy, high stability

✓ Joint Laboratory (Inertial Quantum Sensors for Position and

Navigation)

➢ LP2N: atom interferometry

➢ iXBlue: optical gyroscopes, photonics and inertial

navigation

IXATOM JOINT LABORATORY

8

EXPECTED PERFORMANCES

Performance

Price

Quantity

1 µg

€€€€€€€

◼

100 µg

€€€

◼◼◼

10 mg

100 mg

€

◼◼◼◼◼◼◼

1 mg

10 µg

Applications

Technologies

100 ng

€€€€

◼

10 ng

➢ Long term goal: “GNSS-free” navigation

➢ Bias free accelerometer

➢ Ultra high performance

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✓ Use the same beam for cooling and the

Raman atom interferometer along the 3

axes

✓ Compact sensor head using state of the

art technology

DESIGN OF THE SENSOR HEAD

10

✓ All fibered laser source based on telecom

components and frequency doubling

✓ IQ electro-optical modulator

✓ Fibred switching/spitting bench

DESIGN OF THE LASER SYSTEM

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TRANSPORTABLE 3D ACCELEROMETER

12

Ideal platform to tackle the two

main challenges of strapdown cold

atom sensors:

➢Vibrations

➢Rotations

DOUBLE HYBRIDIZATION

AI Mechanical

accelerometer

Correct slow

drifts

Increase dynamic

range and bandwidth

V. Menoret et al, Sci. Rep 8,12300

(2018)

Large bandwidth

No dead time

Linear response

Bias drifts

Large sensitivity

Very good stability

Dead times

Low data rate

Limited dynamic range

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CONTROLLING THE PHASE OF THE INTERFEROMETER

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෪𝜙𝑖 = 𝑘 ∙ න𝑓 𝑡 Ԧ𝑎(𝑡) d𝑡

• FPGA-based real-time system calculation

• Delay introduced to compensate the finite

bandwidth of the accelerometer

J. Lautier et al, Appl. Phys. Lett. 105, 144102 (2014)

• Controlled phase

• Possible to implement mid-fringe locks

Τ𝑁2𝑁tot

𝜙𝑙𝑎𝑠 (rad)

Real-time compensation by adjusting the laser phase

LOSS OF CONTRAST DUE TO DOPPLER EFFECT

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➢ Doppler shift due to large vibrations and tilts can

tune the Raman transitions out of resonance

𝛿𝐷 = 𝑘 ∙ න Ԧ𝑎(𝑡) d𝑡

➢ Doppler shift calculated in real-time and

compensated before each pulse

Real-time compensation of the Doppler effect by adjusting the laser frequency

REAL-TIME COMPENSATION SYSTEM

Closed loop-operation

➢ The loop can be closed to obtain a hybrid sensor with real-time compensation

➢ Compensation on both the laser frequency and phase

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➢ Tested for moderate vibrations, need to be tested for strong vibrations

ATOMIC FRINGES WHILE ROTATING THE SENSOR HEAD

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TILTING THE QUANTUM SENSOR

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Real-time compensation of the Doppler effect by adjusting the laser frequency

T = 2 ms

T = 10 ms

➢ Interferometer is run at different tilt angles

with the real-time compensation.

➢ Contrast is maintained over a large range.

➢ Close to the horizontal, the contrast is lost

due to the finite size of the beam and mixing

with parasitic interferometers.

LOSS OF CONTRAST DUE TO STRONG ROTATIONS

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+

➢ Alternative measurement of the three axes (qx,y,z~ 45° with the vertical) and the norm of the vector |g|

➢ Tilt of the experiment is drifting dq~6mrad over 10 hours

3D ATOM ACCELEROMETER

TO BE PUBLISHED

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102 103 104

100

10-1

Integration time (s)

Alla

n d

evia

tion (m

g)

aX

aY

az

|a|

➢Simultaneous measurement

possible

[Barrett2019] Barrett et al Multidimensional Atom Optics

and Interferometry, PRL, 122, 043604 (2019)

400 ng

Two orientations:

✓ Vertical: gravimeter mode

✓ Symmetric tilt (q=55°)

ACCURACY OF THE QUANTUM ACCELEROMETER

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Vertical (T = 20 ms) Symmetric Tilt (T = 10 ms)

Systematic effect Value (μg) Uncertainty (μg) Value (μg) Uncertainty (μg)

Scale factor error 2.46 0.49 -27.73 0.67

Parasitic lines 0.192 0.005 < 0.100 < 0.010

Two-photon light shift 0.053 0.001 1.761 0.041

Wavefront distortion 0.020 0.007 0.020 0.007

Quadratic Zeeman 0.002 0.028 -0.007 0.017

Gravity gradient 0.003 < 0.001 < 0.001 < 0.001

Coriolis effect 0.000 0.003 -2.14 0.20

Total 2.72 0.49 -28.00 0.70

Main limitation: Related to

real time compensation

(frequency jumps)

Rejection of some systematic

errors by alternating the k vector

and measure alternatively at high

and full power

✓ Algorithm based on [Yang2012]

RELATIVE ANGLES CALIBRATION

22[Yang2012] J. Yang et al, “Improved iterative calibration for triaxial accelerometers based on

the optimal observation”, Sensors 12, 8157–8175 (2012)

Error on the angle ~ 5 mrad|a|=g

Challenge with cold atoms:

angle dependent bias

classical quantum

✓ 1 hour of warm up

✓ 14 hours of static operation

✓ Long term stability : ~400 ng @ 104 s on the vector

acceleration

MEASUREMENT CAMPAIGN IN SAINT GERMAIN (OCTOBER 2019)

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T= 5 msTilt of the sensor head q=55°

Drift in the orientation of the sensor

head : ~50 mrad over 14 hours

Saint-Germain

Bonneuil

Lannion

Talence

La Ciotat

Besançon

✓ Measurement campaign on board a truck

➫Mobile tests (temperature, vibrations…)

➫Measurements between Paris and Bordeaux

✓ Measurement campaign on board a boat

➫Compensation of the rotation

➫Improvements of the sensitivity in terms of accelerations

➫Measurement campaigns during 12 hours (navigation)

FUTURE CAMPAIGNS

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✓ Hybrid quantum classical sensor

✓ First 3 axis atom interferometer working in any random

direction

✓ Unique platform to tackle vibrations and rotation issues

for strapdown device

✓ Towards a field campaign

✓ Next step: Hybridization with fibred gyroscopes

SUMMARY

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GRAVITY MAPPING WITH A BIASLESS ACCELEROMETER

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-GNSS signal provides direct position information with a position

(white) noise 𝜎𝑧

- Initial gravity map EGM2008 characterized by an error standard

deviation 𝜎𝑚,𝑖 and a correlation length 𝐿𝑐𝑜𝑟𝑟.

𝑔 = ሷ𝑥𝐺𝑁𝑆𝑆 − 𝑎𝑎𝑐𝑐

𝑣 = 2𝑚/𝑠 𝜎𝑛 = 2 𝜇𝑔/ 𝐻𝑧 𝜎𝑚,𝑖 = 5 𝜇𝑔

𝐿𝑐𝑜𝑟𝑟 = 10 𝑘𝑚 𝜎𝑧 = 1𝑚𝑚/ 𝐻𝑧

➢Perfect accelerometer: 370 ng with a correlation length of 100 m

Performances of our hybrid accelerometer:

Long term stability: 200 ng

Bias uncertainty: 700 ng (vertical axis 500 ng)

Goal : 500 ng (calibration improvement)

gain

GRAVITY MATCHING NAVIGATION

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It requires a better map to benefit from the absolute character of the quantum accelerometer

Gravity Matching Accelerometer Gravity map

Blue No Classical EGM2008 (5 µg)

Red Yes Classical EGM2008 (5 µg)

Yellow Yes Quantum EGM2008 (5 µg)

Purple Yes Classical Improved map (1 µg)

Green Yes Quantum Improved map (1 µg)

MINIATURIZATION

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Miniaturization of the sensor head

(ANR MiniXQuanta, Patent N° 20 03648)

-Hybridization of a grating and an atom chip

-Using the diffracted beam for multi axis atom interferometry

Miniaturization of the laser source

-hybridization of components

-Micro-optics, Photonic Integrated Circuits…

COLD ATOM GYROSCOPES

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➢Multi-axis (vector rotation)

➢Robust scale factor➢Atomic beam

➢Ultra compact

➢High atom flux

➢Guided Atoms

➢Atom chips

➢Hollow core fibers

ROADMAP

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First Space atom

accelerometer

20222016

Miniaturized

accelerometer

2025 2030

Bias free 3D

accelerometer

20352020

Bias free 3D

accelerometer

on the field

Starting a gyroscope

activity

First gyroscope

prototype

gyroscope on

the field

Gravity mapping

Gravity matching

Navigation

Navigation

Space applications

✓ First cold-atom based device that can measure the full

acceleration vector, and with state-of-the-art precision

✓ Alternative measurement between X, Y, Z and the

direction of the wave vector

THREE AXIS QUANTUM ACCELEROMETER

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Tilt of the sensor headq=55°

Sensitivity per shot: X: 10.8 mg

Y: 5.5 mg

Z: 4.4 mg

INERTIAL NAVIGATION ERRORS

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CORIOLIS ACCELERATION

ΔΦ = 𝒌𝒆𝒇𝒇 ∙ 𝒂 + 2 𝒗 × 𝜴 𝑇2

Coriolis Term

v

W➢ Temporal response

➢ Weight function

Δ𝜙 = −න𝑔𝜃 𝑡 𝒌𝒆𝒇𝒇 × 𝒗 𝑡 ∙ 𝜴 𝑡 𝒅𝒕

−නන𝑡

∞

𝑔𝜃 𝑡′ 𝒌𝒆𝒇𝒇 × 𝒂 𝑡′ ∙ 𝜴 𝑡 𝑑𝑡′ 𝑑𝑡

𝑔𝜃 𝑡 = 𝑡𝑔𝑆 𝑡 + න𝑡

∞

𝑔𝑆 𝑡′ 𝑑𝑡′

33

v

HYBRIDIZATION WITH A CLASSICAL ACCELEROMETER

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