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Excited state spatial distributions in a cold strontium gas
Graham Lochead
Outline
• Motivation and Rydberg physics
• Experimental details
• Rydberg spatial distributions
The strontium Rydberg project – April 2012
Strong interactions
The strontium Rydberg project – April 2012
Eint > Epot,Ekin
Problem: Correlations make modelling difficultSolution: Simulate in controlled environment
Quantum simulator
The strontium Rydberg project – April 2012
Need single site addressability
Need strong interactions
Weitenberg et al, Nature 471, 319–324 (2011)
…
•
…Rydberg atoms
Rydberg properties
The strontium Rydberg project – April 2012
n = 5
n = 8
n = 7
n = 6
Ionization limit
Properties
High principal quantum number n
n = 68n = 67
n = 66
H ~ 0.1 nm
n = 100 ~ 1 μm
Rydberg physics
The strontium Rydberg project – April 2012
Strong, controllable interactions
Dipole blockade
The strontium Rydberg project – April 2012
Separation
En
erg
y
One excitation per atom pair when
Interaction shift
Experimental blockade
The strontium Rydberg project – April 2012
L. Isenhower et al, Phys. Rev. Lett. 104, 010503 (2010)
Saturation ofexcitation
CNOT gateoperation
H. Schempp et al, Phys. Rev. Lett. 104, 173602 (2010)
Experimental plan
The strontium Rydberg project – April 2012
Project aim
The strontium Rydberg project – April 2012
Position
Colu
mn
den
sity
Excited stateGround state
Investigate excited state spatial distributions
T. Pohl et al, Phys. Rev. Lett. 104, 043002 (2010)
Cold atom setup
The strontium Rydberg project – April 2012
• Zeeman slowed atomic beam
• 5 x 106 strontium atoms at ~5 mK
• 2 x 109 atoms/cm3
• Rydberg laser locked using EIT
R. P. Abel et al, Appl. Phys. Lett. 94, 071107 (2009)
Coherent population trapping
The strontium Rydberg project – April 2012
• Ions detected on MCP
• Ions Rydberg atoms
• Sub natural linewidth
• Control mJ
5s2
5s5p
5sns(d)
λ1 = 461 nm
λ2 = 413 nm
Autoionization
The strontium Rydberg project – April 2012
5s2
5s5p
5sns(d)5s Sr+
5pns(d)
λ1 = 461 nm
λ2 = 413 nm
λ3 = 408 nm
• Resonant ionization
• Independent of excitation
• State selective
5s Sr+ e-
J. Millen et al, Phys. Rev. Lett. 105, 213004 (2010)
Focusing and translating
The strontium Rydberg project – April 2012
Spatial distribution
The strontium Rydberg project – April 2012
Focus coupling beam as well
Scan one direction along ensemble
Ground state from camera image
2D spatial distribution
The strontium Rydberg project – April 2012
Ground state Excited state
Multiple slices → 2D spatial map
Looking for blockade
The strontium Rydberg project – April 2012
Vary density of ground state
Looking for blockade
The strontium Rydberg project – April 2012
No blockade so farDenser sample needed → second stage cooling → dipole trap
Summary
The strontium Rydberg project – April 2012
• Rydberg states have strong interactions
• Coherently excited cold strontium to Rydberg states
• Measured excited state spatial distributions
The team
The strontium Rydberg project – April 2012
Matt Jones
Danielle
Boddy
Charles Adams
ChristopheVaillant
DanielSadler
Me
The strontium Rydberg project – April 2012
Laser stabilization
The strontium Rydberg project – April 2012
5s2
5s5p
5sns(d)
λ1 = 461 nm
λ2 = 413 nm
R. P. Abel et al, Appl. Phys. Lett. 94, 071107 (2009)
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