Post on 05-Jan-2016
TALKING DIRECTLY TO RYDBERG STATES
Yan Zhou, David Grimes, Ethen Klein, Timothy Barnum, Robert Field
laser mmW
MOS seminar 2014.4.22 2
Global model
Valence state (v, N)
Core-penetrating Rydberg state(v, N) = Σ(v+, N+, l)
Core-nonpenetrating Rydberg state(v+, N+, l)
laser mmW
Completely coupled Partially decoupledSeveral ion states
Completely decoupledOne ion state
PhysicsIon-core isolated from
the outside world
ChemistryStrong Ion-electron
collisionsMultichannel
collision Electron probes ion
molecular ion
Global model
JILA seminar 20140612 3
THz spectroscopy
CH3F
H2CO• Detection sensitivity is low• Multiphoton-ionization• Lack of narrow band generation (~0.1THz)• Experiment seems not to fit Rydberg molecules
* Collaborate with Prof. Keith Nelson
JILA seminar 20140612 4
Millimeter wave spectroscopy
• Initialized by Prof. Dan Kleppner• Resolution -> millimeter-wave
Unit: MHz
-60 -40 -20 0 20 40 60
0.00
0.01
0.02
0.03
0.04
0.05
0.06
0.07
PF
I sig
nal/a
rb.u
.
mmW detuning/MHz
5MHz
(b)
JILA seminar 20140612 5
Difficulties• Ion detection – Stray electric field – 5MHz resolution• Intensity fluctuations• Data record: (20GHz / 100kHz) x 1s = 60 hours!• Manipulations: Multi-dimensional spectroscopy, 60n hours!
Weapons• CPmmW spectrometer
• 20GHz bandwidth, 50kHz resolution• Detection efficiency improvement 10000
• Buffer gas cooling molecular beam source• Number density improvement 1000• Beam velocity improvement 10
Total improvement: 108!
Molecular system - BaF
C2Π
X2Σ+
~20100 cm-1
~18600 cm-1
IP0=38745 cm-1
n~40, ln-1, l+1
n+1, l+1v+=0, N+
D0=48200 cm-1
v+=1
v+=2
probe laser/cm-1
mill
imet
er w
ave/
GH
z
1.8455 1.846 1.8465 1.847 1.8475 1.848 1.8485
x 104
75
80
85
90
95
2 4 6 8 10 120
0.2
0.4
0.6
0.8
1
1.2
1.4
1.6
1.8x 10
-3
mmW frequency on scope/GHz
FID
1.1 1.11 1.12 1.13 1.14 1.15
1
2
3
4
5
6
7
8
9
10
11
x 10-5
7.79 7.795 7.8 7.805 7.81 7.815 7.820
2
4
6
8
10
12
14
16
x 10-4
• 200 new transitions / hour• Laser resolution: 1 GHz• mmW resolution: 50 kHz
All people like hydrogen
All people like CNP states!
Let us go with CNP states only!
JILA seminar 20140612 8
Stark demolition
CNPCP
CP or CNP
1V/cm CNP, l>4FID
no FID
CP
2.15 2.2 2.25 2.30
0.5
1
1.5x 10
-3
2.15 2.2 2.25 2.30
0.5
1
1.5x 10
-3
8.05 8.06 8.07 8.08 8.09 8.1 8.11 8.12 8.13 8.14 8.150
2
4
6
8x 10
-4
8.05 8.06 8.07 8.08 8.09 8.1 8.11 8.12 8.13 8.14 8.150
2
4
6
8x 10
-4
CNP
CP
~10MHz
JILA seminar 20140612 9
155 160 165 170 175 180 185 190 195155
160
165
170
175
180
185
190
195
Probe laser detuning/GHz
mm
W/G
Hz
Laser forbidden CNP states
laser
mmW
mmW
laser
CP
CP
CNP
CNP-CNP transitions
CP, l=3
CNP, l=4
mmW1 mmW2
CNP, l=5
Blind search:
• A pulse sequence with 3 or more 20 GHz chirps
• Not increase the search time
mmW multiple resonances
Current work: Collecting all such CNP-CNP transitions
mmW3
CNP, l=6
JILA seminar 20140612 11
n=41 n=42 n=43 n=44
2𝑅
𝑛3
n=42
n=43
n=44
n=45
−𝑅 /𝑛2
n=40
n=41
75-1
00 G
Hz
12 cm-1
2B 4BΔl=+1Δl=-1
Δl=-1 2B 4B
2B
JILA seminar 20140612 12
User friendly assignment recipe
• Good quantum numbers: N, parity, lR
• Pattern forming quantum numbers: N+, l• Key information: IP -> quantum defects• Tools:
• Rydberg formula , (Atom)• Selection rules: , (Polarizations) (Completely determined by
experiments)• Propensity rules: (Atom)• Reduced energy plot:
No sophisticated pattern recognition and fitting programMost information comes from experiments directly
A calculator is enough!
( , ) ( 1) ( 2 ...)rot R RE N l B N N B Nl
RRR RRQ RQR QRR RQQ QRQ QQR QQQ0
1
2
3
4
5
Tra
nsiti
on In
tens
ity
probe laser/cm-1
mill
imet
er w
ave/
GH
z
1.8455 1.846 1.8465 1.847 1.8475 1.848 1.8485
x 104
75
80
85
90
95
Organize transitions
(1) Rydberg formula (2) Up/down transitions (3) Stark demolition – CP or CNP
CPCNP
Thank you for your attention!