IHP Quantum Information Trimester

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Niels Bohr Institute Copenhagen University
Light-Matter Quantum Interface
Eugene Polzik LECTURE 2
IHP Quantum Information Trimester
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Interaction Hamiltonian for polarized light and
spin-polarized atomic ensemble Teleportation
protocols using atoms-light interface
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Polarization quantum variables Light
Propagation direction
vertical
horizontal
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Polarization variables for light
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Polarization homodyning - measure X (or P)
Polarizing Beamsplitter 450/-450
Strong field A(t)
x
Quantum field a -gt X,P
Polarizing cube
S1
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Polarization states with vertical classical
component
To detection
Polarization beamsplitter
x
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Preparation of the input state of light
Strong field
Quantum field
x
Polarizing cube
X
Polarization state
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Macroscopic spin ensemble coherent spin
state
x
X
z
y
State preparation (optical pumping)

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6P3/2
Cesium as a spin ½ system
6S1/2
Spherical chicken
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Off-resonant intercation with spin ½ atoms
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Dynamics of light and atoms
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Physics behind the Hamiltonian 1. Polarization
rotation of light
Polarizing Beamsplitter 450/-450
x
Quantum field
Polarizing cube
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Physics behind the Hamiltonian 2. Dynamic Stark
shift of atoms
Atoms
atoms
Strong field A(t)
Quantum field - a
x
Polarizing cube
y
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Initial collective spin state coherent
spin state
Cesium

X
State preparation (optical pumping)
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Alexandrov et al 1986 Sorensen et al 1998
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Light rotates atomic spin Stark shift
XL
Atomic spin rotates polarization of light
Faraday effect
Output light
Input light
Light-Matter Entanglement generated
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Figure of merit for the quantum interface
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Teleportation principle (canonical variables)
L.Vaidman
Demonstrated experimentally for light variables
by Furusawa, Sørensen, Fuchs, Braunstein
Kimble, Polzik. Science 1998