Studying our cold Rydberg gas James Millen

Level scheme (5s 2 ) 1 S 0 461nm 32MHz (5s5p) 1 P 1 (5sns) 1 S 0 (5snd) 1 D 2 Continuum ~413nm Studying our cold Rydberg gas – group meeting

Experimental sequence (see last group meeting) Studying our cold Rydberg gas – group meeting Strontium loaded into MOT from Zeeman slowed beam MOT beams provide first excitation photon Laser at 412nm provides second photon, always on Electric field plates direct charge onto MCP Average heavily on oscilloscope Timing and read-out via LabView

Studying our cold Rydberg gas – group meeting Spectrum

Line analysis Can use quantum defect analysis to try and identify series δ = n – n*n* = √(R sr /T n ) T n = E ion - E 1 S 0 δ= D 2 δ=2.38 Studying our cold Rydberg gas – group meeting

Acquisition Studying our cold Rydberg gas – group meeting

High resolution Studying our cold Rydberg gas – group meeting These spectra were taken using laser scan, requires >100 averages… Can instead step the laser in frequency, and read out every time, limited by wavemeter accuracy.

Stark effect Studying our cold Rydberg gas – group meeting Our field plates can create a uniform electric field

Mysteries/Problems (I) Studying our cold Rydberg gas – group meeting Our ion signal is tied to the number of atoms in our MOT:

Mysteries/Problems (I) Studying our cold Rydberg gas – group meeting The ions hang around for a very long time…

Mysteries/Problems (II) Studying our cold Rydberg gas – group meeting How many Rydberg atoms are we creating?

Mysteries/Problems (III) Studying our cold Rydberg gas – group meeting How are we making ions‽ We make up to ~4 Vcm n = 85 the field for ionisation is ~ 6Vcm n = 50 the field for ionisation is ~ 50Vcm -1 Collisions? Black body ionisation? Need to avoid building up charge

“Stark shuttering” Studying our cold Rydberg gas – group meeting