Handling interactions in Stata Handling interactions in Stata
Measurement of atom-surface interactions by atom ...
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Measurement of atom-surface interactions by atom
interferometry Matthias Büchner
Laboratoire Collision, Agrégats, Réactivité UMR 5589
IRSAMC
Outline
Introduction: Principle of an Mach-Zehnder interferometerAtom diffraction by a standing laser wave in the Bragg regime
Our atom interferometer
Measurement of the van der Waals interactionnon-Newtonian gravitation
ConclusionOutlook
Mach-Zehnder interferometers
beam splittermirror
mirror
light wave
beam splitterDétecteur
optic:
Atoms:optics:
• propagation in atmosphere• velocity : c= 300 000 km/s • wavelength : λλλλopt= 633 nm • time of flight (L= 1 m): T= 3 ns
• beam splitter/miroirs: standard
↔
↔
↔
↔
↔
in vacuumv= 1 km/s (thermal lithium beam)de Broglie: λλλλdB=h/(mv) ≈ 54 pmT= 1 ms extreme sensitivity to inertial effects
???
Détecteur sortie1
(0)
~λdB/a
(1)
(-1)
(2)
Atom interferometer with separated pathsCoherent manipulation of atomic waves
grating
a
Atom beam
(λdB) L L
Beam splitter
Mirrors recombining beam splitter
Mach-Zehnder atom interferometer with amplitude grating s
λdB.L/a
The mirrors and beam-splitters of the Mach-Zehnder optical interferometers are replaced by nanograting diffraction
1991-2004 group of David E. Pritchard at MIT2004 - group of A. Cronin at Univ. of Arizona
for Sodium waves
+ versatile instrument+ many experiments were carried out- low transmission- low visibility due to multiple diffraction orders
Period = 100 nmFront View
Mach-Zehnder interferometers
Lithium waveDiffracting gratings
pmmv
hdeBroglie 54≈=λ
Grating period 100 nm ⇒ diffraction angle ≈ 540 µrad ⇒ L=1 m : arm separation ≈ 0. 5 mm
The mirrors and beam-splitters of the Mach-Zehnder optical interferometers are replaced by Bragg diffraction on laser standing waves
In the Bragg regime, diffraction of order p>1 can be used.
Atom diffraction by light waves
The process
ω, kL
ω,kL|a>
|c>
keff= 2kL
Probability of the process:∝∝∝∝ laser detuning ∆∆∆∆-1
∝∝∝∝ laser power∝∝∝∝ interaction time
The photon wavelength should not be resonant with an atomic transition If not : decoherence by spontaneous emission (population of state |c>)
effect ∝∝∝∝ detuning ∆∆∆∆-2
h∆∆∆∆
⇒⇒ need of a powerful single frequency cw laser need of a powerful single frequency cw laser with a wavelength close to an atomic transitionwith a wavelength close to an atomic transition
⇒⇒⇒⇒⇒⇒⇒⇒ Selective for atoms and their isotopesSelective for atoms and their isotopes
energy
katom
Bragg diffraction
|k, a>
kL
Thick light wave : ∆y →uncertainty principle ⇒∆ky=0 : k || xθB kL
|k+2k L, a>
Condition of Bragg diffraction : BRAGG angle
λL= 671 nmλde Broglie = 54 pm
θB = p λdB/ λL
= 80 µrad (p=1)
p = diffraction order|k, a>
∞
x
y
mirror
|k+4k L, a
>
p=1|k, a>
|k, a>
p=2
2θB
θB = p λdB/ λL
= 160 µrad (p=2)
Only diffracted beam : no loss of atoms !!
Bragg diffraction
transmitted wave: order 0
Diffracted wave : order 1
Rabi oscillation - laser power- laser detuning from an atomic
resonance- laser waist (interaction time)
0 20 40 60 80 100 120 140 160 1800
5k
10k
15k
20k
25k
30k
35k
40k
45k
50k
55k
intensity of 1st order diffraction (c/s)
laser power (mW)
mirror
beam splitter
+ no stray beams+ choice of diffraction order+ choice of diffraction amplitude
|k+2p >kL
|k>
p=1
Three grating atom interferometerStanding laser waves
M1 M2 M3
•
x
z
y
Alignment condition : k+2kL(1) - 2kL
(2) = k+2kL(2) - 2kL
(3)
phase related to diffraction: ϕ= 2kL (2 x2 – x1 – x3 ) scan the fringes
∆x3 = 53 nm ↔ ∆ ϕ = 1 rad
I=I0·[1+V ·cos(ϕmirror)]V: visibilityI0: mean flux
+2kL(1)
+2kL(2)
-2kL(2)
-2kL(3)
k
Our atom interferometer
Ionization detector(hot wire)
Standing laser waves
pθB
18 µm18 µm
source Collimation slits
lithium+ rare gas
Detection slit
0,6m
M1 M2 M3
800 °C
0,6m
krypton hélium750 m/s <vLi < 3500 m/s
∆x
∆∆∆∆x∝∝∝∝p/vLi typ. 100µm for 1000 m/s, p=1200 µm, p=2 ..
0,8m
Critical alignment: collimation, Bragg angle, mirror positions Critical alignment: collimation, Bragg angle, mirror positions
≈ 30 µm
≈ 50 µm
Strong collimation of the atom beamStrong collimation of the atom beam
Our interferometer fringes
p = 1
visibilityV = 84.5 ±±±± 1%
mean fluxI0 = 23700 c/s
0.0 335.5 671.0 1006.5 1342.00
5k
10k
15k
20k
25k
30k
35k
40k
45k
Signal (c/s)
x - position du miroir M3 (nm)
I=I0·[1+V ·cos(ϕmirror)]
sensitivity around15 mrad/√Hz
Interferometric measurements
We applied our atom interferometer for the mesure of theWe applied our atom interferometer for the mesure of the
- electric polarisability of 7Li- refraction index of rare gases for lithium matter waver- atom surface interaction (van der Waals interaction) and we are mesuring now a topological phase
Perturbation U
with T ≈ 100 µµµµs
1 second mesure:∆Φ∆Φ∆Φ∆Φmin = 15 mrad
1000 m/s 10 cm
ηη
/)(1
UTdttU ≈=∆ ∫φ
Umin = 1.5 ××××10-32 J= 10-13 eV = 20 Hz
Our measurement of the vdW interaction
Motivation Motivation work of Perreault, J. D. and Cronin, A. D., PRL 95, 133201 (2005)
Several diffraction orders exist→But only order « 0 » contributes to the dephasing
Test of atom-surface interaction For distances between 0 and 26 nm over a length of 110 nm
window
Nanograting :Surface of silicon nitride covered by Au/Pd
period : (100±0.1) nm, width of the window: (53±1) nm,
Thickness: (110±5) nm
Our measurement of the vdW interaction
A collaboration between the Arizona and Toulouse groups was created
Why using our interferometer?
• low phase noise
• only two atom beams interfereinterpretation is far more easier
• another atom: Li instead of Na (group of arizona)
Our measurement of the vdW interaction
window
C: the 2 beams go through the window
CB A
B: one beam goes through the grating
A: both beams go through the grating
Our measurement of the vdW interaction
⇒⇒⇒⇒dephasing ∝∝∝∝ v-0.49
We changed the atom velocity (750 – 3300 m/s)
2nd order diffractionError bar of ±100 mrad
Perreault, and Cronin, PRL 95, 133201 (2005) our results
Li
Velocity dispersion of the vdW phase
∫⋅= dzwzV
v vdW ),,(1
)( ξξδφη
33
33
2/2/),,(
ξξξ
−−+
+−=
w
C
w
CwzVvdW
>ξ
w VvdW
Integration over the trajectories ξFourier optics:Diffraction amplitude of 0th order: ∫∝Φ ξξδφ dwieA i )];(exp[0
0
We measure this phase
X
Dispersion de la phase vdW en vitesse
dephasing:One area contributes the mostThis area depends on the velocity
X
X
vLi= 750 m/svLi= 3500 m/s
Origin of the interaction
C3/r3
C3 = (3.25 ± 0.2) meV·nm3
χ2(p)
⇒⇒⇒⇒ Signature of the van der Waals interaction
Model potential : Cp/rp
Test of non Newtonnian gravitation
Modified potential:
Amplitude Portée
correction type « Yukawa »
Constraints over α and λ :
(α,λ) adjust C3 for Φ0(v) Comparing theresiduals
rejection
acceptation
MotivationMotivation : research of a 5th force
Newton
Sonde de la gravitation non Newtonienne
Our resultats : (λ,αλ,αλ,αλ,α)
(α,λ) = (<1028,1 nm) (α,λ) = (<1026,2 nm) (α,λ) = (<1023,10 nm)
Our data points
excluded regionEderth
vdW
neutron (a)
neutron (b )
Figure : extracted from Fischbach et al. PRD 64, 075010 (2001)and H. Abele (2008)Progress in Particle and Nuclear Physics 60, 1 (2008)
Neutron a,b : Limits from neutron–nucleus scattering and neutron optics dataH. Leeb, J. Schmiedmayer, PRL 68 (1992) 1472.
Ederth: V.M. Mostepanenko and M. Novello, Phys. Rev. D 63, 115003 (2001),T. Ederth, Phys. Rev. A 62, 062104 ~2000!.
vdW: M. Bordag, V.M. Mostepanenko, and I.Yu. Sokolov, Phys. Lett. A 187, 35 (1994) Y.N. Israelachvili and D. Tabor, Proc. R. Soc. London A331, 19 (1972)
-We are actually measuring the He-McKellar-Wilkens eff ecttopological phase resulting from (induced) dipoles m oving in magnetic
fields
-Measurement of dephasing/decoherence of matter waves b y radiation
-Construction of a 2 nd generation atom interferometeratoms with v=10-1500 m/s, slowed by radiation forcesbrilliant lithium atom beam, high flux, small veloci ty distribution
active stabilized interferometer bench
-Measurement of the retarded van der Waals interaction (Casmir-Polder interaction)
-matter neutrality …..
-
Outlook
in collaboration with
V.P.A Lonji A.D. Cronin
University of Tuscon, Arizona, USA
Funding from ANR, MENRT, CNRS, Université P. Sabatier, IRSAMC, Région Midi-Pyrénées
From left to right:Steven LepoutreJacques ViguéMatthias BüchnerGérard TrénecHaikel JelassiGilles Dolfo (not present)
Toulouse group
S. Dimopoulos and A. Geraci (PRD 2003)
(extracted from Fischbach et al.PRD, 64, 075010)
Our measurement ( λ,αλ,αλ,αλ,α)
Constraint on α and λ :
(α,λ)Fit C3 for Φ0(v) Comparaiso
n of residuals
Acceptation
Rejection
(α,λ) = (<1028,1 nm) (α,λ) = (<1026,2 nm)
(α,λ) = (<1023,10 nm)
vdW : Y.N. Israelachvili and D. Tabor, Proc. R. Soc. London A331, 19 (1972)Ederth ,: T. Ederth Thomas PRA 62 062104 (2000)
|α||α||α||α|
Calcul de (7Li) :
soit
(forces d’oscillateurs des transitions)
C3 = 3,12 meV.nm 3 cohérent avec C3 = 3,25 +/- 0,2 meV.nm 3
(exp)
Transition de résonance (2s →
2p)
Autres transitions
Force d’oscillateur
0.746 0.254
Polarisabilitéstatique α0
(164,111 u.a. Z.-C. Yan,
PRA 1996)
99% (αres=161,945 u.a.)
1,32% (2,166 u.a.)
Projet I : mesure d’une phase topologique
Le premier exemple d’une phase topologique :
la phase d’Aharonov-BohmY. Aharonov and D. Bohm, Phys. Rev. 115p 485 (1959)
déphasage des franges d’interférences
La famille des effets topologiques
>µµµµ
e+e+e+e+e+>
e+
µµµµ
µµµµ
µµµµ
Aharonov-Bohme+ : particule chargéeµµµµ : dipôle magnétiqueg+ : monopôle magnétique d : dipôle électrique
>g+
d
d
d
Aharonov-Bohmdual
>d
g+g+g+g+
g+
E ↔↔↔↔ Be+ ↔↔↔↔ g+
d ↔↔↔↔ µ
Aharonov-Casher
He-McKellar-Wilkens
L’effet HeMcKellar-Wilkens
>d
g+g+g+g+
g+·
E
Li
50 mm
B
B
Ed=αE
U=½ α α α α E’ 2=½ α α α α (E+v××××B)2 =½ ααααE2 +ααααE·((((v××××B)+α ()+α ()+α ()+α (v××××B)))) 2
- 3 µrad- Identique pour chaque brasB= 112 Gauss
E= 0.85 MV/m24 mrad
-450 rad, mais- identique pour les 2 bras
ExpExpéérience en coursrience en cours
·
Projet II: Un interféromètre de 2 ème génération
•• Construction dConstruction d’’ une source de lithiumune source de lithium
- flux élevé
- accordable vers 100 m/s
- faible dispersion en vitesse (1%)
•• CrCrééation dation d’’ un banc dun banc d’’ interfinterfééromromèètre suspendu et stabilistre suspendu et stabiliséémméécaniquement caniquement Pourquoi ? Pourquoi ?
ϕ= 2pkL (2 x2 – x1 – x3 )
M1M3M1 M2
Rotation : ϕSagnac= 4pkL Ω(y) L T, T : temps de vol
Accélération : ϕacc = pkL a(x) T2
grâce à des méthodes d’optique atomique
p=5100 m/s
L
∆∆∆∆x=5 mm
Projet : Neutralité
Neutralité de la matière : charge du neutron=0 ?charge de l’électron= - charge du proton ?
Pourquoi une telle symétrie entre leptons et quarks ?
Incertitudes actuelles:charge du neutron : qn=(0.4 ±1.1) 10-21 qe
neutralité e- - p : ≈ 10-21 qe
EstEst--ce que lce que l’’ interfinterfééromroméétrie atomique est capable de trie atomique est capable de repousser ces limites ?repousser ces limites ?
Projet : Neutralité
PeutPeut--être oui être oui ……..
Publications:
• C. Champenois et al., dans The Hydrogen Atom: Precision Physics of Simple Atomic Systems, Springer Berlin / Heidelberg, 554-563 (2001) Matter Neutrality Test Using a Mach-Zehnder Interferometer
• R. Delhuille et al., AIP Conf. Proc.-- April 26, 2001 -- Volume 564, pp. 192-199QUANTUM ELECTRODYNAMICS AND PHYSICS OF THE VACUUM: QED 2000,
Atom interferometry: Principles and applications to fundamental physics
• A. Arvanitaki et al. PRL 100, p. 120407 (2008)
How to Test Atom and Neutron Neutrality with Atom Interferometry
Projet : NeutralitéPrincipe de montage expérimental :
E= ± 5MV/m, vLi= 50 m/s∆∆∆∆x (max) = 2 mm, LC= 0.5 mSensibilité actuelle :15 mrad Hz-1/2 ⇒⇒⇒⇒
Tacq ≈ 17 min pour qresi/nucléon < 10-21 e
∫Γ
= λλη dVqresivLi)(1φ
Défis: inhomogénéités du champ E (φpol ≈3·106 rad)Possibilité: hacher le jet et pulser E
A. Arvanitaki et al. PRL 100, p. 120407 (2008) :Fontaine atomiqued’hauteur 10 m : 106 lancements ⇒⇒⇒⇒ qresi/nucléon < 10-28 e