photoassociation spectroscopy of ytterbium atoms with dipole-allowed and intercombination...
TRANSCRIPT
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Photoassociation Spectroscopy of Ytterbium Atoms with Dipole-allowed
and Intercombination Transitions
K. Enomoto, M. Kitagawa, K. Kasa, S. Tojo, T. Fukuhara, A. Yamaguchi, S. Uetake, Y. Takasu, and Y. Takahashi, Kyoto University
Ultracold Group II atoms: Theory and Applications 06/Sep/18 ITAMP
についての COE 報告会
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YtterbiumYtterbium
Group IIGroup II
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Workshop on ultracold group II atoms
2000 Cold Alkaline-Earth Atoms (in ITAMP)
2003 Cold Alkaline-Earth Atoms (in Copenhagen)
2006 Sep/18-20 Ultracold Group II Atoms (in ITAMP)
Atomic clock
Number of invited speakers
Experiment Theory
Photoassociation
Novel species/mixtures
Others
4 1
4 5
5 1
3 5
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Next generation atomic clock
1S0-3P0 atomic transition has extremelynarrow linewidth ( <0.1 Hz), and is inert to a magnetic field. The atoms trapped in an optical lattice with the magic wavelength are free from the Doppler broadening and the collisional shift.
Frequency standard with / ~ 10-17
Precise frequency measurements of Sr and Yb in 1D latticehave been presented (NIST, JILA, SYRTE, PTB groups).
The precision is about 5Hz.
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R
g
Photoassociation (PA)
Ultracold atoms has narrow thermal distribution, so free-boundtransitions (photoassociation) areobserved with high resolution.This photoassociation is a powerfultool for probing rovibrational levelsnear the threshold and scattering states.
Such parameters are determined for Sr, Ca, and Yb.
Atomic parameters such asradiative lifetimes and scatteringlengths are determined precisely.
Theory for optical control of collision, PA in low dimensions
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Novel species/mixtures
Magneto-optical trap (MOT) of Ra (radium, =15day)
Measurement of nuclear EDM
MOT of Li-K-Sr mixture
Novel cooper pair (heteronuclear,FFLO, etc.)
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Summary of my talk
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Level Diagram of Yb
(6s6p)1P1
(6s2)1S0
intercombination transition556 nm, =874ns (Linewidth=182kHz)
(6s6p)3P2
3P13P0
clock transition
dipole allowed, 399 nm=5.5ns (Linewidth=29MHz)
Mass number
Nuclear spin i
Abundance(%)
168
0
0.13
170
0
3.05
171
1/2
14.3
172
0
21.9
173
5/2
16.2
174
0
31.8
176
0
12.7
=15s
~
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Outline
1. Experimental procedure
2. Determination of scattering length of 174Yb
3. Two-color PAS
4. Intercombination PAS of 4 isotopes
5. Optical Feshbach resonance
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atomicbeam
Zeeman slower
Experimental procedure
399 nmZeeman slowing laser ( ~ 40 mW)
anti-Helmholtzcoils
556 nmMOT laser ( ~ 30 mW each)
slower
MOT
horiz. FORT
vertical FORT
PA
probe
~ 10s
~ 6s
~ 100ms
Typical time chart
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Experimental procedure
CCD camera
absorption image
532 nmFORT laser
(7→0.2 W, 0= 12 m) (7 W 0= 80 m)
399 nmprobe laser
( ~ 0.01W/cm2)
556 nmPA laser
( ~ 0.1W/cm2)slower
MOT
horiz. FORT
vertical FORT
PA
probe
~ 10s
~ 6s
~ 100ms
Typical time chart
Off resonance
240m
1.0
0.0tran
smis
sion
On resonance
N ~105
n ~1014 cm-3
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Determination of scattering length of 174Yb using dipole-allowed PAS
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Spectra of dipole-allowed PAS
10 15 20 25 30 350
5
10
345170 175 180 1850
5
10
98103
108
110 113116 118
Detuning (GHz)
Nu
mb
er
of
ato
ms
(10
4 )
156157 158
175
PAS of 1S0-1P1 transition at ~1 K
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Ground-state wavefunction
Wavefunction obtained from PA rates to various vibrational states
3 4 5 6 7 8 9 10 113 4 5 6 7 8 9 10 113 4 5 6 7 8 9 10 11
1
10
Squ
ared
wav
e fu
nctio
n (a
rb. u
nits
)
Internuclear distance (nm)
Scattering length a of 174Yb is 5.53 0.11 nm
C6 potential coefficient is 2300 250 a.u.
(with taking account of other sources of error.)
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Two-color PAS
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Two-color PA spectra of 174Yb
120000
80000
40000
0
Num
ber
of a
tom
s
10.710.610.510.410.310.2
Frequency deference (MHz)
Raman transition
Recently, we succeededin observing two-colorPAS spectra for 174Yb at ~1 K.
12
174Yb 1S0-1P1
Frequency difference (MHz)
Last bound state level 10.63 MHz
11.0
10.8
10.6
10.4
10.2
10.0
f2-f
1 (
MH
z)
-0.4 -0.3 -0.2 -0.1 0.0 0.1 0.2
f (MHz)
Lightshift
Expected shift (MHz)
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Two-color PA spectra of 174Yb
Next-to-the-last state level 268.6 MHz
12
120000
80000
40000
0
Nu
mb
er
of
ato
ms
269.2269.0268.8268.6268.4268.2
Frequency deference (MHz)Frequency difference (MHz)
120000
100000
80000
60000
40000
20000
0
Nu
mb
er
of
ato
ms
360320280240200160
Frequency difference (MHz)
Dark state (1 is scanned)
Autler-Townes spectroscopy(2 is scanned)
These two-color PASresults determine C6 and a more precisely.
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Scattering length of other isotopes
)]8
tan(1[
aa
iR
dRRmV )(21
Gribakin et al., PRA 48, 546 (1993).
The scattering length a can be described with the phase .
Two-color PA spectroscopy of some isotopes will reveal the scattering lengths of all the isotopes and their combinations.
Scattering length
pos. 6 nmsmallneg. ?small small? large?
+10- 5
Mass number 168 170 171 172 173 174 176
~54 Å
Scattering length ~54 Å? Å
Mass number 168 170 171 172 173 174 176
? Å ? Å ? Å ? Å ? Å
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Intercombination PAS of bosonic (i=0) isotopes (174Yb, 176Yb )
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PA spectrum of 174Yb
v’ = 8v’ = 9
v’ = 10 v’ = 7T ~ 4 K
At a low temperature of~4 K, only transitionfrom s-wave scatteringstate was observed.
Even the vibrational levelat 3 MHz from the disso-ciation limit was resolved.
v’ : vibrational number counted from the dissociation limit.
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PA spectra of 174Yb & 176Yb (T~25 K)
174Yb
Je = 1
Je = 1
Je = 1
Je = 3
Je = 3
Je = 3
v’ = 16
v’ = 14
v’ = 10
RC=6.5 nm
RC=8.6 nm
RC=17.4 nm Je = 1
Je = 1
Je = 3
Je = 3
Je = 1
Je = 3
v’ = 16
v’ = 13
v’ = 10
RC= 6.0 nm
RC= 9.0 nm
RC=15.1 nm
176Yb
Large difference in signal intensity
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Difference between 174Yb & 176Yb
The PA efficiency for Je=3 line of 174Yb is large inside the centri-fugal potential barrier.
This is due to shape resonance.
wavefunction near shape resonance
d-wave potential
wavefunction far fromshape resonance
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Intercombination PAS of fermionic (i0) isotopes (171Yb, 173Yb )
L
S JaI
F
T
hyperfine coupling coupling to molecular axis
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Potential calculation
B111
3
A201
B201
A1113 ,PSS,P ff
B111
3
A201
B201
A1113 ,PSS,P ff
iiii islf
21 ffF
,
)(3
221132121 jijia
r
ddddH zz
iii slj
id
:transition dipole, a:hyperfine coupling constant
171Yb (3P1) ‥ i =1/2, j =11S0, f1=1/2
3P1, f2=3/2,1/2
basis sym.:
basis antisym.:
,i and are projection of and to molecular axis, respectively.if
F
,
i
i
j
f(1S0) ‥ i =1/2, j =0
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Pair potential of 171Yb2 [1S0+3P1(f=3/2)]
Hyperfine-induced purely long-range states exist.
2 4 6 8 10 12 14-1200
-1000
-800
-600
-400
-200
0
200
En
erg
y (M
Hz)
Internuclear Distance (nm)2 4 6 8 10 12 14
-1200
-1000
-800
-600
-400
-200
0
200
En
erg
y (M
Hz)
Internuclear Distance (nm)
F = 1, = 0 = 2
= 1
= 1
F = 2, = 0
state sym.: state antisym.:
s,d-wavep,f-wave
f=3/2 f=3/2
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20000
15000
10000
5000
0Nu
mb
er
of A
tom
s
-280 -260 -240 -220 -200
Frequency Detuning (MHz)
PA spectrum of 171Yb
p waves wave
T=1T=2 T=3 T=1 p s
purely long-range state
-400 0-1000 -200-800 -600
f =3/2
(MHz)
-1060MHz ~ -160MHz
Temperature ~20 K
p
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ConclusionPAS with the intercombination transition
d-wave shape resonance is inferred for 174Yb.Hyperfine-induced purely long-range state was observed.
PAS with the dipole-allowed transitiona = 5.53 ± 0.11 nm, C6 = 2300 ± 250 nm for 174Yb
Two-color PAS of 174YbBound levels at 10.6 MHz and 268.6 MHz were found.
Optical Feshbach resonance with the intercombination line
The asymmetric spectrum implies the change of a.
3P2 state atoms are trapped in the optical trap with high density.
Quantum degenerate gases have been achieved for 5 isotopes.