Excited state spatial distributions in a cold strontium gas Graham Lochead.
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Transcript of Excited state spatial distributions in a cold strontium gas Graham Lochead.
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Excited state spatial distributions in a cold strontium gas
Graham Lochead
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Outline
• Motivation and Rydberg physics
• Experimental details
• Rydberg spatial distributions
The strontium Rydberg project – April 2012
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Strong interactions
The strontium Rydberg project – April 2012
Eint > Epot,Ekin
Problem: Correlations make modelling difficultSolution: Simulate in controlled environment
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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
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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
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Rydberg physics
The strontium Rydberg project – April 2012
Strong, controllable interactions
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Dipole blockade
The strontium Rydberg project – April 2012
Separation
En
erg
y
One excitation per atom pair when
Interaction shift
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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)
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Experimental plan
The strontium Rydberg project – April 2012
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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)
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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)
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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
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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)
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Focusing and translating
The strontium Rydberg project – April 2012
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Spatial distribution
The strontium Rydberg project – April 2012
Focus coupling beam as well
Scan one direction along ensemble
Ground state from camera image
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2D spatial distribution
The strontium Rydberg project – April 2012
Ground state Excited state
Multiple slices → 2D spatial map
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Looking for blockade
The strontium Rydberg project – April 2012
Vary density of ground state
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Looking for blockade
The strontium Rydberg project – April 2012
No blockade so farDenser sample needed → second stage cooling → dipole trap
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Summary
The strontium Rydberg project – April 2012
• Rydberg states have strong interactions
• Coherently excited cold strontium to Rydberg states
• Measured excited state spatial distributions
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The team
The strontium Rydberg project – April 2012
Matt Jones
Danielle
Boddy
Charles Adams
ChristopheVaillant
DanielSadler
Me
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The strontium Rydberg project – April 2012
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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)