URECA Celebration Research ofUndergraduate Creativity, and Brook, Stony April • 24th NY the increasing radial distance of each orbital as This is a diagram of Hydrogen as described by been the focusofmany research projects in the past several decades. Due to these interesting properties, creating and studying Rydberg atoms has • • • • These Rydberg atoms have several interesting properties. attractive force from the nucleus and istherefore quite weakly boundto it. separation from the nucleus, the outer electron experiences a very weak orbital A Rydberg atom isan excited atom with one ormore electrons in a very high the Rydberg formula and gives a basic picture to the structure ofan atom. system-like picture to describe the Hydrogen Atom. This model corroborates We can then further expand ourunderstanding ofatoms byat Bohr’s 1913solar structure ofan atom still was being debated at this time. formula In 1888Rydberg created a generalized version of state. metastable state Helium (He*)to Rydberg states byexploiting an intermediary the light associated with the 1to 2transition. We excite an atomic beam of associated with the counter-intuitive order. The counter-intuitive order means that the laser light effectively donot populate the intermediate state ofthe system if weusethe ithow can achieve 100%population transfer. This ispossible because we excite atoms to Rydberg states with n=15-50. The theory ofSTIRAP describes STIRAP, Stimulated Rapid Adiabatic Passage,isusedin ourexperiments to

Atoms wehave. applying a voltage difference. This wemeasure ishow many how Rydberg actually quite fragile. This means wecan remove it from its orbital by classical electron orbiting a nucleus Long lifetime Because ofits huge size, ,the electron in the high energy state is Under some conditions, the electron in the high norbital behaves like a Exaggerated responseto external electric and magnetic fields

n. for the wavelengths ofthe atom. H This isimpressive because the The name isusually usedwhenn>15.Because ofits large physical

2 to 3state transition interacts with the atomic beam before Atomic Physics Rydberg Atoms [4] thesis, Lu,StonyBrook University,[3] X. Ph.D. 2011 [2] [1] Figures from postersby:

Petr Xiaoxu Xiaoxu Bohr Atom

r Anisimov STIRAP ! Lu et al., Bull. Soc. Am. Phys. Lu et al., Bull. Soc. Am. Phys. n 2

n et al., Bull. Soc. Am. Phys. = 4 Balmer’s Neils

56 55

r

, No. 5,152(2011), No. 14. Q1 5,119341, No. 00089 (2010) K1 57

! simple empirical , No. 5, 99 (2012) K1 19. 5,99(2012)K1 , No. Bohr in 1913. Note n 2 LaserUsing LighttoExcite Helium Atoms Stony Brook University, Stony Brook 11794-3800 NY

James Dragan, Yuan Harold Sun, Metcalf, [4] [3]

[3] 2.3 kV Source

[3] Rydberg State to High Energy States

792-830nm Interaction Chamber Helium Energy Levels discharge Excitation by STIRAP v 796 nm Vacuum System Source Chamber 389 nm

Detector Beams STIRAP

Coherent Model Electro-Optics Ti:Sapphire Tekhnoscan Ti:Sapphire doubled by MBD 200 MBD frequency Schwartz Lasers Full-Width at Longitudinal

Half-Max The Experimental Setup Velocity Avg.

; LN2cooled

He*beam

Tunable from "Blue Light" 690-1100nm "Red Light" doubled to frequency 778nm; 1070m/s 389nm 480m/s

Diagram Simplified

optical molasses to decrease this velocity spread. Shifting them out of resonance. Recent experiments have been conducted using We believe this isdue to the transverse velocity spread ofatoms that results Doppler Rydberg state. Experimental results have only achieved ~50%population transfer. Theory that suggests weshould be able to achieve 100%population transfer to the and geometry ofMCP. signal, gain isrelated to the electric field which amplify(MCP) the original detection. two Uses Ion Detector [1] Rapid Passageutilizes the counter-intuitive order to populate the third state

Stimulated Adiabatic -For Rydberg-For atom [1] Past Efficiency Measurements microchannel

Detection Systems [3] plates

STIRAP Work the Office by issupported of NavalResearch. measurements onthe atomic distribution. atomic beam giving quantitative us We are able to move it perpendicular to the results in a cascade ofelectrons from the MCP. He*. A He*atom ejects an electron which MCP’s allowing to us detect electrons from the Stainless Steel Detector 1 2 3 intuive order

me

through the STIRAP beam. 1083 nm, after they pass a laser ofwavelength unexcited He*atoms using is done bydeflecting all the STIRAP light beams. This throughHe* passes the Atom production asthe the efficiency ofRydberg These measurements show - two uses The SSD counter-intuive order

me [3]