Dipole-dipole interactions in Rydberg states. Outline Strontium experiment overview Routes to...

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Dipole-dipole interactions in Rydberg states
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Page 1: Dipole-dipole interactions in Rydberg states. Outline Strontium experiment overview Routes to blockade Dipole-dipole effects.

Dipole-dipole interactions in Rydberg states

Page 2: Dipole-dipole interactions in Rydberg states. Outline Strontium experiment overview Routes to blockade Dipole-dipole effects.

Outline

• Strontium experiment overview

• Routes to blockade

• Dipole-dipole effects

Page 3: Dipole-dipole interactions in Rydberg states. Outline Strontium experiment overview Routes to blockade Dipole-dipole effects.

Team strontium

Matt Jones Charles Adams

Me Dan Sadler

DanielleBoddy

ChristopheVaillant

Page 4: Dipole-dipole interactions in Rydberg states. Outline Strontium experiment overview Routes to blockade Dipole-dipole effects.

Rydberg physics

Rydberg atoms:

• States of high principal n

• Strong, tunable interactions

Position

Co

lum

nd

en

sity

Excited state

Ground state

Page 5: Dipole-dipole interactions in Rydberg states. Outline Strontium experiment overview Routes to blockade Dipole-dipole effects.

Spatial measurements

Automatictranslation state

Lens setup

Page 6: Dipole-dipole interactions in Rydberg states. Outline Strontium experiment overview Routes to blockade Dipole-dipole effects.

Autoionization

5s2

5s5p

5sns(d)5s Sr+

5pns(d)

λ1 = 461 nm

λ2 = 413 nm

λ3 = 408 nm• Resonant ionization process

• Increases signal over spontaneous ionization

• Independent excitation and detection

• Can give spectral and temporal information

Page 7: Dipole-dipole interactions in Rydberg states. Outline Strontium experiment overview Routes to blockade Dipole-dipole effects.

Preliminary results

Time

Repeat

MOT + Zeeman

MOT + Zeeman

Probe +

Coupling

(1 μs)

408

pulse

(1 μs)

Electric

field pulse

(5 μs)

• ~106 atoms at 5 mK• Camera image for atom number• 408 is focused to 10 μm• Translation stage stepped• Ions detected on an MCP

Page 8: Dipole-dipole interactions in Rydberg states. Outline Strontium experiment overview Routes to blockade Dipole-dipole effects.

Increasing density

5s2 1S0

5s5p 1P1

5s4d 1D2

5s6s 3S1

5s5p

3P2

3P1

3P0

461 nm

679 nm 707 nm

Current cooling scheme has leak

Repumping increases density by approximately an order of magnitude

Page 9: Dipole-dipole interactions in Rydberg states. Outline Strontium experiment overview Routes to blockade Dipole-dipole effects.

Förster zeros

T.G. Walker and M. Saffman, PRA 77, 032723 (2008)

Long range van der Waals interaction couples pairs of states

: radial part of the interaction

: angular part of the interaction

Förster zero is where is zero

Sum over all final states to get total interaction

Page 10: Dipole-dipole interactions in Rydberg states. Outline Strontium experiment overview Routes to blockade Dipole-dipole effects.

Quantization coils I

Apply magnetic field to define quantization axis

Polarization well defined, can excite specific mJ

Need to switch fast

Avoid losing density

External coils too slow

Eddy currents in chamber

Page 11: Dipole-dipole interactions in Rydberg states. Outline Strontium experiment overview Routes to blockade Dipole-dipole effects.

Quantization coils II

Solution: Use internal coils

Vertical excitation beams are orthogonal to autoionizing beam

Page 12: Dipole-dipole interactions in Rydberg states. Outline Strontium experiment overview Routes to blockade Dipole-dipole effects.

Internuclear axis

Internuclear axis aligned with quantization axis

mJ projection good

Internuclear axis not aligned with quantization axis

mJ projection varies

Solution: Use S states or make geometry 1D

Page 13: Dipole-dipole interactions in Rydberg states. Outline Strontium experiment overview Routes to blockade Dipole-dipole effects.

Summary

• Signal to noise of spatial measurements is good

• Close to blockade densities

• Need to control polarization to avoid Förster zeros