Excited state spatial distributions

Graham Lochead20/06/11

Outline

• Rydberg spatial distribution

• Locked coupling laser spectra

• Preliminary spatial distributions

Graham Lochead20/06/11

Motivation

Col

umn

dens

ity (

arb.

uni

ts)

Distance (microns)

Ground state

Excited state

Separation

Inte

ract

ion

ener

gy

Graham Lochead20/06/11

Experimental procedure

Automatictranslation stage

Lens setup

Graham Lochead20/06/11

Autoionization

• Allows independent Rydberg excitation and investigation

• Ion detection is very sensitive

5s2 5s5p 5sns(d) 5pns(d) 5s1/2+

Graham Lochead20/06/11

Ion spectrum experimental setup

Time

Probe +

Coupling

(1 μs)

MOT +

Zeeman

Electric

field pulse

(5 μs)

MOT +

Zeeman

Repeat

408

pulse

(1 μs)

• Probe frequency stepped• Camera image taken for atom number• 100 ns between excitation pulses• 408 not at focus

Graham Lochead20/06/11

56D spectrum

Example ion signal

Integrate to get each point

Example Rydberg spectrum

Graham Lochead20/06/11

MOT coil turn off

Varying time between MOT coil switch off and excitation beams

• Zeeman effect

• Previously did not have the resolution to see this splitting

• Set Δt to be 400 μs to avoid this

Graham Lochead20/06/11

Ion spectrum characterisation

Graham Lochead

Translation experiment setup

Time

Probe +

Coupling

(1 μs)

MOT +

Zeeman

Electric

field pulse

(5 μs)

MOT +

Zeeman

Repeat

408

pulse

(1 μs)

• Probe frequency set to max ion signal• 408 is at focus• Translation stage stepped

Graham Lochead20/06/11

Translation signal-to-noise

• Focused 408 addresses few atoms

• Autoionising signal may be small

• Spontaneous ionization is a problem

• D states are repulsive

Graham Lochead20/06/11

Chi-squared fit

Gaussian fit to all data

Graham Lochead20/06/11

Do not expect Rydberg Blockade at this n or density

Average of three translation runs with standard error

Reaching Rydberg Blockade

Graham Lochead

Two ways to reach blockade:

• Increase n

• Increase density

Higher n error signals

Graham Lochead20/06/11

Main constraint for higher n is laser locking signal n-3

Repump lasers

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 order of magnitude

Graham Lochead20/06/11

Summary / Outlook

• Repeatable ion spectra

• Preliminary spatial distributions

• Need to increase density

Graham Lochead20/06/11