Cold Atom Surface Interactions

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Cold Atom - Surface Interactions By Michael
Morrissey Quantum Optics Group, Cork Institute
of Technology, Ireland
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Outline

• Source of cold rubidium atoms
• Diffraction of cold atoms off a microsphere
• Diffraction of cold atoms off an atomic grating

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Source of Cold Atoms
Pirani Gauge (2.3x10-9 mbar)
Ion Pump (V7kV)
Anti-Helmholtz Coils 4A
Rb Source (3A)
Roughing Pump (1x10-2 mbar)
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Investigation I Microspheres
WGM
Material IOG-2 Phosphate Size 50 ?m - 100?m
Dopants Ytterbium, Erbium Pump 980nm
(15mW) Emission 1550nm and 520/540nm
Pump 980nm
Fibre optic
Microsphere
CO2 Laser
3 ?m
125 ?m
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Proposed Experiment
We propose to study the scattering of slow atoms
that pass in the evanescent field of a
microsphere WGM.
MOT
Atoms are released from the MOT and fall into the
small space between the diaphragm D and the
microsphere S.
D
Atoms are deflected by evanescent field of the
WGM at the spheres equator. The deflection
angles, are revealed by the ring-shaped
distribution of atoms in a horizontal plane below
.
S
By observing the atom diffraction due to the
microsphere and making a comparison with the
theoretical diffraction pattern, information
should be gathered concerning the role played by
repulsive and attractive forces in the regime.
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Investigation II Magnetic Grating
A magnetic mirror can be an array of wires in
which adjacent wires have current flowing in
opposite directions W mirror width a
periodicity L wire length
A magnetic mirror can be made operate as a
grating by introducing a small oscillation in the
magnetic field. Piezoelectric crystal,
modulating current, coils
N 1
N 0
?
?n
N -1
BR
The location yR of the potential barrier will
oscillate in time according to
yR D.Cos(?t)
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Frequency of Oscillation
N2
Angle of Reflection
N1
N-1
N-2
Frequency (MHz)
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Angular Resolution
The angular resolution of diffracted orders can
be given by
Angle of Reflection
Angle of Reflection
Angle of Reflection
Angle of Incidence
Angle of Incidence
Angle of Incidence
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Amplitude of Different Orders
D 1/k
Amp2
Diffraction Order
D 2/k
D 1/2k
Amp2
Amp2
Diffraction Order
Diffraction Order
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Amplitude of Different Orders
D 1/k
Amp2
Diffraction Order
D 2/k
D 1/2k
Amp2
Amp2
Diffraction Order
Diffraction Order
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Thank you for your attention! THE END