Excited state spatial distributions in a cold strontium gas Graham Lochead

Outline Motivation and Rydberg physics Experimental details Rydberg spatial distributions The strontium Rydberg project – April 2012

Strong interactions The strontium Rydberg project – April 2012 E int > E pot,E kin Problem: Correlations make modelling difficult Solution: Simulate in controlled environment

Quantum simulator The strontium Rydberg project – April 2012 Need single site addressability Need strong interactions Weitenberg et al, Nature 471, 319–324 (2011) … …Rydberg atoms

Rydberg properties The strontium Rydberg project – April 2012 n = 5 n = 8 n = 7 n = 6 Ionization limit Properties High principal quantum number n n = 68 n = 67 n = 66 H ~ 0.1 nm n = 100 ~ 1 μ m

Rydberg physics The strontium Rydberg project – April 2012 Strong, controllable interactions

Dipole blockade The strontium Rydberg project – April 2012 Separation Energy One excitation per atom pair when Interaction shift

Experimental blockade The strontium Rydberg project – April 2012 L. Isenhower et al, Phys. Rev. Lett. 104, (2010) Saturation of excitation CNOT gate operation H. Schempp et al, Phys. Rev. Lett. 104, (2010)

Experimental plan The strontium Rydberg project – April 2012

Project aim The strontium Rydberg project – April 2012 Position Column density Excited state Ground state Investigate excited state spatial distributions T. Pohl et al, Phys. Rev. Lett. 104, (2010)

Cold atom setup The strontium Rydberg project – April 2012 Zeeman slowed atomic beam 5 x 10 6 strontium atoms at ~5 mK 2 x 10 9 atoms/cm 3 Rydberg laser locked using EIT R. P. Abel et al, Appl. Phys. Lett. 94, (2009)

Coherent population trapping The strontium Rydberg project – April 2012 Ions detected on MCP Ions Rydberg atoms Sub natural linewidth Control m J 5s 2 5s5p 5sns(d) λ 1 = 461 nm λ 2 = 413 nm

Autoionization The strontium Rydberg project – April s 2 5s5p 5sns(d) 5s Sr + 5pns(d) λ 1 = 461 nm λ 2 = 413 nm λ 3 = 408 nm Resonant ionization Independent of excitation State selective 5s Sr + e-e- J. Millen et al, Phys. Rev. Lett. 105, (2010)

Focusing and translating The strontium Rydberg project – April 2012

Spatial distribution The strontium Rydberg project – April 2012 Focus coupling beam as well Scan one direction along ensemble Ground state from camera image

2D spatial distribution The strontium Rydberg project – April 2012 Ground state Excited state Multiple slices → 2D spatial map

Looking for blockade The strontium Rydberg project – April 2012 Vary density of ground state

Looking for blockade The strontium Rydberg project – April 2012 No blockade so far Denser sample needed → second stage cooling → dipole trap

Summary The strontium Rydberg project – April 2012 Rydberg states have strong interactions Coherently excited cold strontium to Rydberg states Measured excited state spatial distributions

The team The strontium Rydberg project – April 2012 Matt Jones Danielle Boddy Charles Adams Christophe Vaillant Daniel Sadler Me

The strontium Rydberg project – April 2012

Laser stabilization The strontium Rydberg project – April s 2 5s5p 5sns(d) λ 1 = 461 nm λ 2 = 413 nm R. P. Abel et al, Appl. Phys. Lett. 94, (2009)