Transcript Single Site Addressability in a CO2 Lattice

Rydberg excitation laser locking for
spatial distribution measurement
Graham Lochead 24/01/11
Outline
• Rydberg spatial distribution
• Coupling laser locking
• Cold atom experiments
Rydberg spatial distribution
Ground state
Rydberg state
Density (arb. units)
V
Low
density
High
density
Distance (microns)
Experimental procedure
Automatic
translation stage
Lens setup
Autoionization
• Allows independent Rydberg
excitation and investigation
• Ion detection is very sensitive
5s2
5s5p
5sns(d)
5pns(d)
5s1/2+
Progress towards experiment

Translation stage testing

Lens design and testing

Incorporation with main LabVIEW program

Laser locking

Rest of the optical layout
Test signal-to-noise of focussed autoionization pulse
Laser locking
Need to lock coupling laser (5s5p → 5sns(d)) – previously stepped
Stepping gives incoherent transfer
- Blockade harder to achieve
Use modulation spectroscopy
R.P. Abel et. al, Appl. Phys. Lett. 94, 071107 (2009)
Autoionization laser will be stabilized using digital
PID lock to the wavemeter
Frequency (MHz)
Frequency modulation spectroscopy
G.C. Bjorklund et. al, Appl. Phys. B 32, 145-152 (1983)
EOM
Cell

PS

Filter
9.45 MHz
Oscilloscope
EIT locking difficulties
• Have to lock offresonance
• Narrow absorption
profile in cell
• Absorption quite low
461
Cell
413
EIT locking solution
Problem: EIT signal too small
Solution: Use an optical chopper
EOM
Cell
413

PS
Chopper

Filter
9.45 MHz
Lock-in
Oscilloscope
EIT characterization
Cold atom setup
Probe +
Electric
Coupling
field pulse
(10 μs)
(10 μs)
MOT +
10 μs
MOT +
Zeeman
Zeeman
Time
Repeat
Spontaneous ionization with locked lasers
Fit = 31 MHz
Natural linewidth = 32 MHz
Narrower – coherent population
transfer
Temperature = 6 mK
Doppler width = 5 MHz
Outlook
• Can now lock both lasers
• Test autoionization SNR