bose-einstein condensation (a tutorial) melinda kellogg wyatt technology corporation santa barbara,...
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Bose-Einstein Bose-Einstein CondensationCondensation
Melinda KelloggWyatt Technology Corporation
Santa Barbara, CAJune 8, 2010
Satyendra Bose(1894 – 1974)
Fermions Bosons
Spin
Elementary particles also spin…
electron: spin ½ proton/neutron: spin ½
quark: spin ½
photon: spin 1
graviton: spin 2 Higgs boson: spin 0
half-integral spin: electrons, protons,
neutrons…
zero or integral spin: Higgs bosons, photons,
helium-4 atoms, sodium-23,
rubidium-87 atoms…
Fermions Bosons
obey Pauli exclusion principledon’t obey
Pauli exclusion principle
Albert Einstein(1879 – 1955)
e-
e-
e-
e-
e-
e-
e-
e-
Bose-Einstein Condensate
where:
m
n
km
nT
Bc
3223
2
23
2
)(
Critical Temperature
First Bose-Einstein Condensate (BEC):
Superfluid He-4KTc 17.2
a better BEC requires weaker interatomic interactions…
a diffuse gas
m
nTc
32
Laser Cooling
stationary atom absorbs green photon
and shortly thereafter re-emits it
slightly detune laser towards the red…
photon passes through, unless…
photon is Doppler shifted
appears green to atom
atom is moving toward light source,
laser
Laser (Doppler) Cooling
cools to ~ 150 μK
Evaporative Cooling
Magnetic Trap
low fieldseeking
high fieldseeking
Magnetic Potential Energy
BU S
N
BU
BU 0U
Magnetic Trap
Evaporative Coolingm
ag
neti
c fi
eld
str
en
gth
position
Evaporative Coolingp
ote
nti
al en
erg
y
position
Evaporative Cooling
position
E
mag
neti
c fi
eld
str
en
gth
Evaporative Cooling
position
E
mag
neti
c fi
eld
str
en
gth
Evaporative Cooling
position
E
mag
neti
c fi
eld
str
en
gth
Evaporative Cooling
position
mag
neti
c fi
eld
str
en
gth
Evaporative Cooling
position
B ~ 30 MHz
mag
neti
c fi
eld
str
en
gth
Evaporative Cooling
position
mag
neti
c fi
eld
str
en
gth
Evaporative Cooling
position
E
mag
neti
c fi
eld
str
en
gth
Evaporative Cooling
cools to < 1 μK
BEC of Sodium Atoms
Durfee & Ketterle, Optics Express 2, 299 (1998)
Thank you!Thank you!