REALIZATION OF A MAGNETICALLY GUIDED BEAMIN THE COLLISIONAL REGIME

T. Lahaye, Z. Wang, J. Dalibard and D. Guéry-OdelinLaboratoire Kastler Brossel, Ecole Normale Supérieure, 24 rue Lhomond, 75005 Paris (France)

MOTIVATIONAtom lasers from BEC

Injector MOT Magnetic guideand evaporation

OUR PROJECT

PULSED INJECTION

REFERENCES

Radiofrequency outcoupler

[1] E. Mandonnet A. Minguzzi, R. Dum, I. Carusotto, Y. Castin and J. Dalibard, Eur. Phys. J. D 10, 9 (2000).[2] P. Cren, C. F. Roos, A. Aclan, J. Dalibard and D. Guéry-Odelin, Eur. Phys. J. D 20, 107 (2002).[3] C. F. Roos, P. Cren, J. Dalibard and D. Guéry-Odelin, Physica Scripta T105, 19 (2003) and cond-mat/0212060.[4] C. F. Roos, P. Cren, T. Lahaye, J. Dalibard and D. Guéry-Odelin, Laser Physics 13, 605 (2003) and cond-mat/0212147.[5] T. Lahaye, P. Cren, C.F. Roos and D. Guéry-Odelin, Comm. Nonlin. Sci. Num. Sim., 8, 315 (2003) and cond-mat/0211661.[6] C. F. Roos,P. Cren, D. Guéry-Odelin and J. Dalibard, EuroPhys. Lett., 61, 187 (2003).[7] J. M. Vogels, T. Lahaye, C. F. Roos, J. Dalibard and D. Guéry-Odelin, cond-mat/0404560.[8] T. Lahaye, J. M. Vogels, K. Günter, Z. Wang, J. Dalibard and D. Guéry-Odelin, to appear in Physical Review Letters, cond-mat/0405013.

Transpose to an atomic beam the techniques used on atom clouds.Goal: achievement of a continuous and intense cold atomic beam, magnetically guided,

with a low mean velocity.Apply transverse evaporative cooling [1]. If the initial collision rate is highenough, quantum degeneracy can be reached after a few meters.

Low flux < 104 atoms/s1 monolayer on 1 m2 in 3 years

Oven T= 140-170 °C

Oven flux = 1.5 1012 atoms/s

Flux of slow atoms:

2. 1011 atoms/s

at a mean velocity of the order

of 15 m/s.

Anisotropic 3D magnetic gradient

Six beams MOT

Capture rate > 2. 1010 atoms/s

Adjustable launching velocityfrom 0.3 m/s to 3 m/s

Pulsed injection in the guide, overlap after 70 cm propagation:

3 to 4 packets per second: Flux of the order of 7.109 atoms/s

probe

TEMPERATURE MEASUREMENT WITH ONE RF ANTENNA

“Red” trajectory is not evaporated“Blue” trajectory is evaporated

T=380 µK

1.0

0.5

0.00 10 20 30

N’/N

d1, ? ? A2, ? ?dA1 A2

EXPERIMENT WITH TWO ANTENNAS

WITH COLLISIONS d=3 mWITHOUT COLLISIONS

ν1= 8 MHz

Radio frequency (MHz)

N’’/N’

D. Guéry-Odelin, J. M. Vogels, K. Günter, A. Senger, T. Lahaye, J. Dalibard, Z. Wang

Previous members: J. M. Vogels, K. Günter, C. F. Roos, A. Aclan, P. Cren

Rubidium Oven

Zeeman SlowerZeeman Slowerbeam, 780 nm

Rb

MOT beam, ν-MOT beam, ν-

MOT beam, ν+ MOT beam, ν+

x

yz

Probingzone

Magnetic guide

MOTchamber

15 mm400 A

Magnetic gradient300 G/cm

14 mmAtoms

ENTRANCE OF THE MAGNETIC GUIDE

OVEN AND ZEEMAN SLOWERMAGNETO-OPTICAL TRAP

Antenna 1

Antenna 2

TAPERED SECTIONOF THE MAGNETIC

GUIDE

d

Time (s)

24

42

1

1.5

1.0

0.5

0.0

0 3 6

Area

(a.u

.)

00

8

5 10 15 20 25Number of launches

Abso

rptio

n (a

.u.) a) b)

REALIZATION OF A CONTINUOUS BEAM

OUTLOOKSlope to slow down the beam

Start forced evaporative coolingwith many antennas

Dark line MOT.

4.5

met

er

300 G/cmfor I=400 A.

1000 G/cmfor I=400 A.

0.4 meter

EXPERIMENTAL SETUP

1.0

0.5

0.00 10 20

1.0

0.5

0.00 10 20 300 10 20 30

T=380 µK T=280 µK

Heating Cooling

0.5

1.0

1.5

0 1 2 3 4 5

T 2 / T1

η1

THE TEAM

1.0

0.6

0.20 10 20 30 40 50 60

µ

νRF

νRF

νRF