LongLived Quantum Memory with 3He Nuclear Spins

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Long-Lived Quantum Memorywith 3He Nuclear Spins
A. Dantan, G. Reinaudi, A. Sinatra, F. Laloë, E.
Giacobino, M. Pinard Laboratoire Kastler
Brossel, UPMC, ENS Paris, France
YAO 2006, 18/02/06
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Context Quantum Info

• Quantum state transfer storage
• between matter and light
• Atomic ensembles
• long lifetime, collective effect, continuous
  variables
• Quantum memory alkali atoms
• Longer times? Collective nuclear spin
• ? 3He vapor

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He3 ground state nuclear spin
23P0
20 eV
11S0
Lifetime hours!
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He3 ground state nuclear spin

• Optical coupling
• 1.08 µm

23P0
20 eV
23S1
2. MEC
11S0
Lifetime hours!
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Quantum noise
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Atomic collective spin

• N 2-level atoms N spins ½
• Collective operators
• Quantum noise

e
g
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Atomic collective spin

• N 2-level atoms N spins ½
• Collective operators
• Quantum noise
• Coherent spin state

e
g
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Squeezing transfer

• Optical coupling
• 1.08 µm

23P0
23S1
2. MEC
11S0
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1. Quantum state transfer
?A? 0 A broadband squeezed vacuum ?X ?Y ?02
?Sz? N/2 metastable coherence harm.
osc. ?Sx ?Sy N/4

• Resonant Raman process
• ? efficient squeezing transfer

Dantan et al. PRA 69, 043810 (2004)
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2. Metastability exchange collisions
1 meta. and 1 fund. atom exchange electronic
variables

• MEC conserve one-body observables
• polarized 3He by optical pumping
• (Colegrove, Shearer Walters 63)

Medical imaging applications
Quantum info?
Nuclear physics
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Toy model results
Optical pumping/metastable collision rate
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Interpretation

• Correlation transfer
• MEC equalize correlations

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Realistic case
B field, finite metastable atom lifetime
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Realistic case
B field, finite metastable atom lifetime
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Results
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Feasibility

• B field (hom. lt 100ppm)
• Low frequency squeezing
• Resonant excitation
• Laser stability Hz
• Long access time 2s
• Limited by metastable atom density n

• 1.08µm efficient sources and nonlinear crystals
  (KTP)
• MEC high polarization rate (80-85 weak field)
• Strong collective coupling achievable in cell
• Storage time hours

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Perspectives

• Optical readout after storage ? quantum memory
• Increase metastable density ? faster access time
• NMR techniques ? manipulation
• Dantan et al. PRL 95, 123002 (2005)
• Reinaudi et al. quant-ph/0512186

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Toy model results
Optical pumping/metastable collision rate
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Atomic collective spin

• N 2-level atoms N spins ½
• Collective operators
• Quantum noise
• Coherent spin state
• Correlations

e
g