Experimental Atomic Physics Research in the Budker Group

Transcription

1 Experimental Atomic Physics Research in the Budker Group Tests of fundamental symmetries using atomic physics: Parity Time-reversal invariance Permutation Postulate/Spin-Statistics Connection Temporal variation of fundamental constants Applied atomic spectroscopy Sensitive magnetometry and electrometry (NMR, magnetic anomalies, space, ) Nonlinear optics with atoms Optical properties of superfluid helium New atomic energy levels Properties of complex atoms: the rare earths, Ba

2 Our group

3 Group Demographics and Philosophy 6 graduate students 1-3 undergrads 1 staff scientist Lots of visitors from US and abroad; ongoing collaboration with groups in [Poland, Latvia, India, Armenia, and Russia], [LANL, NIST, LBNL, UCB Chemistry, ] Each student has their own project Lots of interactions within group Variety of experiences and techniques: lasers, optics, atomic beams and vapor cells, cryogenics, computer control and data acquisition, vacuum, electronics, theory, scientific writing and editing,..

4 Further information: Office: 273 Birge; labs: 217,219,221,230,241, and 245 Birge

5 Provides Unique Low-Energy Test of the Standard Model Atomic Parity Nonconservation e γ Z e Electromagnetic interaction (conserves parity) r r Π Ψ ( ) = ± Ψ ( ) Π Weak interaction (violates parity) r Ψ ( ) ± Ψ ( Small Modifications of the Optical Properties of Atoms r )

6 PNC Experiments Electric and magnetic fields define a handedness PNC effects show up as dependence of atom-photon interaction on handedness Photo-multiplier tubes Oven Collimator Ytterbium atoms Light guide PBC mirror z E y B e x 408-nm light Electric field plates 649-nm light Magnetic field coils Parabolic reflector Two Experiments in Progress: Dysprosium (Z=66) and Ytterbium (Z=70)

7 Yb Interaction Region

8 How constant is the fine structure constant α? EXPERIMENTAL Astrophysical:. α/α = (-7.2 ± 1.8) /yr [J. K. Webb, et al., Phys. Rev. Lett. 87, (2001).] THEORETICAL Theories that unify gravity with other forces either allow or necessitate α variation Geophysical: Oklo natural nuclear reactor 1.8 billion years ago:. α/α < /yr Laboratory: H-maser vs. Hg+ microwave clock:. α/α < /yr Rb vs. Cs microwave clocks:. α/α < /yr Hg+ optical vs. Cs microwave clocks:. α/α < /yr

9 20,000 A. α in dysprosium B ν ~ MHz levels A and B are highly sensitive to variations in α Energy (cm -1 ) 0 Ground State ν.. ν ~ Hz α/α. i.e. for α/α ~ /yr. ν~ 2 Hz/yr rf freq. generator E-field plates atomic freq. standard atomic beam fluor. PMT

10 NONLINEAR MAGNETO-OPTICAL OPTICAL ROTATION Goal: Obtain highest possible sensitivity to magnetic fields. F = 0 Use laser light to polarize atoms: (1) Aligns magnetic dipole moments; (2) Creates preferred optical axis. F = 1 M F = -1 M F = 0 M F = +1 Magnetic moments precess in magnetic field: Optical axis rotates causes light polarization to rotate. ϕ = g F µβ/γ rel 1 + (g F µβ/γ rel ) 2

11 Paraffin-coated cells look like Christmas ornaments! Slow relaxation of atomic polarization: γ rel 1 Hz Β ~ 1 µg ~ 0.1 nt Rotation Angle (mrad) Magnetic Field (nt)

12 Pumping and probing with FM light FM NMOR magnetometry: Phys.Rev.A65, (2002)

13 Precision magetometry and atomic EDM measurement using spin-polarized atoms in a buffer gas at cryogenic temperatures Problem: to measure very small B; to measure electron EDM Paramagnetic atom magnetometer; He buffer gas at T=4K to increase spin-relaxation time to minutes Measuring the Kerr effect in LHe and the LANL neutron EDM experiment Problem: to measure strong electric fields (50kV/cm) inside a bath of LHe at 300mK. Kerr effect: an initially isotropic medium acquires birefringence when electric field is applied, measure this.

14 241 Birge, midnight, 8/25/03

15 Neutron EDM experiment at LANSCE Light Guides Cells Between Electrodes HV and Ground Electrodes Beam Entrance Window Cosθ Coil SQUID Enclosure HV Variable Capacitor

16 Laser spectroscopy for fundamental symmetry tests Motivation: BEV exp Lifetimes, branching ratios, new levels, polarizabilities (Ba) Unusually large polarizabilities (100 times; for n<10, only smaller than 2s,2p of H) new opposite-parity levels Electron EDM exp Noncontact circuit board testing

17 Probed States Laser Excitation nm Fluorescence ~ 435 nm 6s6p 1 P 1 6s6p 3 P 0,1,2 Laser Excitation nm 6s 21 S 0 Even Parity Odd Parity

18 What is the experiment? A test of the spin statistics theorem (SST) for photons. What is the SST?

19 Barium How we do it

20 Interaction region

21 Power Build-up Cavity

22 Oven Housing w/collimator 1.04" 0.28" 1.58" 0.95" 0.70" 0.82" 1.22" 1.70"

23 Chamber

24 Numbers

25 Experimental Atomic Physics Research in the Budker Group

26 Papers we wrote/published in 2004 A. T. Nguyen, D. Budker, S. K. Lamoreaux, and J. R. Torgerson, Sensitive search for the temporal variation of the fine structure constant using radio-frequency E1 transitions in atomic dysprosium, Phys. Rev. A 69, (2004) D. Budker, L. Hollberg, D. F. Kimball, J. Kitching, S. Pustelny, and V. V. Yashchuk, Investigation of microwave transitions and nonlinear magneto-optical rotation in anti-relaxation-coated cells; physics/ Review article: E. B. Alexandrov, M. Auzinsh, D. Budker, D. F. Kimball, S. M. Rochester, and V. V. Yashchuk, Dynamic effects in nonlinear magneto-optics of atoms and molecules; to appear in a Special Issue of JOSA B on Nonlinear and Integrated Magneto-Optics; physics/ Comment: D. Budker and S. M. Rochester, A relation between electromagnetically induced absorption resonances and nonlinear magneto-optics in Lambda-systems; physics/ (Accepted to Phys. Rev. A) Yu. P. Malakyan, S. M. Rochester, D. Budker, D. F. Kimball, and V. V. Yashchuk, Nonlinear magneto-optical rotation of frequency-modulated light resonant with a low-j transition, Phys. Rev. A. 69, (2004). physics/ M. Auzinsh, D. Budker D. F. Kimball, S. M. Rochester, J. E. Stalnaker, A. O. Sushkov, and V. V. Yashchuk, Can a quantum nondemolition measurement improve the sensitivity of an atomic magnetometer? physics/ V. V. Yashchuk, J. Granwehr, D. F. Kimball, S. M. Rochester, A. H. Trabesinger, J. T. Urban, D. Budker, and A. Pines, Hyperpolarized xenon nuclear spins detected by optical atomic magnetometry, physics/ (to appear in PRL) A. O. Sushkov, E. Williams, V. V. Yashchuk, D. Budker, and S. K.Lamoreaux, Kerr effect in liquid helium at temperatures below the superfluid transition, to appear in Phys. Rev. Letters; physics/ C.H. Li, S.M. Rochester, M.G. Kozlov, and D. Budker, Unusually large polarizabilities and "new" atomic states in Ba, Phys. Rev. A 69, (2004)

27 We want YOU!