1. T. Inoue, 1 T. Nanao,1 M. Tsuchiya, 1 H. Hayashi, 1 T. Furukawa, 1 A. Yoshimi, 2 M. Uchida, 1 H. Ueno, 2 Y. Matsuo, 2 T. Fukuyama, 3 and K. Asahi 1 1 Tokyo Institute of Technology, Meguro-ku, Tokyo 152-8551, Japan 2 RIKEN, 2-1 Horosawa, Wako-shi, Saitama 351-0198, Japan 3 Ritsumeikan University, Nojihigashi, Kusatsu, Shiga 525-8577, Japan Search for an electric dipole moment in 129 Xe atom using a nuclear spin oscillator Workshop on Fundamental Physics Using Atoms 7 - 9 August 2010, Osaka OUTLINE: 1. Introduction 2. "Optically coupled" spin oscillator 3. Present status 4. Summary

2. s + + + - - - + - +q+q -q-q a = d ≡ qa Electric Dipole Moment (EDM) d or, Electric Dipole Moment 1. Introduction E ext (Permanent) Electric Dipole Moment + + +    = 0

3. Electric dipole moment (EDM) time reversal → s → -s → d spinEDM:: s - -- + ++ d s - -- + ++ d d ≠ 0 ： ：： ： Violation of T ⇒ Violation of CP (CPT theorem) ● The violation of CP is implemented in the Standard Model (SM), but... ● CP violation in SM (K-M mechanism) is not sufficient to explain the matter-antimatter asymmetry observed in the universe. Thus,... ● An extra CP-violation is required.

4. Electric dipole moment (EDM) time reversal → s → -s → d spinEDM:: s - -- + ++ d s - -- + ++ d ： d ≠ 0 ： Violation of T ⇒ Violation of CP (CPT theorem) Sites of EDM searches neutron d N paramagnetic atoms (Tl, Fr, Cs,...) d e diamagnetic atoms ( 129 Xe, 199 Hg, Rn, Ra,...) S molecules (TlF, YbF, PbO, ThO,...) d e charged particles (d, ,...) d N, d  ⇒ Probing different facet ｓ of anticipated new physics

5. Electric dipole moment (EDM) time reversal → s → -s → d spinEDM:: s - -- + ++ d s - -- + ++ d ： d ≠ 0 ： Violation of T ⇒ Violation of CP (CPT theorem) Tl, Fr, Cs… 129 Xe, 199 Hg, Rn, Ra… M. Pospelov and A. Ritz, Annals of Phys. 318, (2005) 119-169 EDM in 129 Xe atoms stable particle macroscopic number of particles EDM generated by a nuclear Schiff moment P,T-violating NN interaction Schiff moment

6. How does the EDM appear in a diamagnetic atom? Point nucleus in an atom Electrostatic  (r) due to a cloud of atomic electrons + d q =  x = d/q Atomic electrons do not "know" whether the nucleus has EDM. Atomic electrons feel a non- trivial charge distribution unside the nucleus. EDM d Nucleus with a finite size q EDM d q = Nucleus q qq

7. Electron cloud

8. Nontrivial charge distribution in the nucleus generates an EDM in atom: Schiff moment d( 129 Xe) = 3.8×10  5 fm  2 ·S( 129 Xe) d( 199 Hg) =  2.8×10  4 fm  2 ·S( 199 Hg) d atom ≠0 Nucleus Electron cloud [ Ginges & Flambaum, Phys. Rep. 397 (04) 63 ]

9. What generates a Schiff moment ? with SkO' effective interaction, [J.H. de Jesus and J. Engel, Ann. Phys. 318 (05) 119] --- (In language of nuclear physics) CP-violating components of the NN interaction generate S. ●Case of 199 Hg ●Case of 129 Xe Flambaum, Khriplovich, Sushkov, 1985 Dzuba, Flambaum, Porsev, 2009 Yoshinaga's group, consideration fro shell model in progress.

10. d( 129 Xe) < 4.1×10 -27 ecm Rosenberry and Chupp, PRL 86 (2001) 22 d( 199 Hg) < 3.1×10 -29 ecm Grifith et al., PRL 102 (2009) 101601 Standard Model (d n = 10 -(31-33) ) Neutron EDM predicted values d = 10  27 e·cm E = 10 kV/cm  = 10 nHz （  1° /day ） [Pendlebury and Hinds, NIM A 440 (00) 471]

11. E // B E //  B Energy shift upon an E-field reversal Shift in a precession frequency the difference ⇒ signal of an EDM B E s B E s Energy levels for a spin 1/2 (for a case of  > 0, d > 0) Detection of an EDM Desires long precession times => Spin maser

12. ― Realization of a long precession time Key issue for a high-sensitivity EDM detection: Free precession Time Transverse spin ‘Spin maser’ state Time Transverse spin

13. Spin maser BB ● 129 Xe polarization vector P =  I  /I ● Static field B 0 = (B x, B y, B 0 ) Pumping term relaxation term [T.E. Chupp et al, Phys. Rev. Lett. 72 (94) 2363] [M.A. Rosenberry and T.E. Chupp, Phys. Re. Lett. 86 (2001) 22] ● P follows the Bloch equations: or,

14. Spin maser BB [T.E. Chupp et al, Phys. Rev. Lett. 72 (94) 2363] [M.A. Rosenberry and T.E. Chupp, Phys. Re. Lett. 86 (2001) 22] ● If a capacitor C is connected to form a resonating circuit, the coil produces a transverse B field, B  (t),

15. Taking (1) + i (2) and setting The steady state solutions ・ Trivial solution: ・ Non-trivial solution:

16. Spin oscillator B(t)B(t) ● Now we devise the transverse part of the B field, B  (t), to follow P  B(t)B(t) Spin detection

17. steady oscillation transient Maser oscillation

18. Setup for the maser experiment Probe laser ・ DFB laser ・ = 794.76 nm (Rb D1line) ・  = 8.4×10 -6 nm ・ Power : 15 mW Pumping laser ・ = 794.76 nm (Rb D1line) ・  = 3 nm ・ Power ~ 11 W PEM Heater /4 plate Si photodiode ・ Bandwidth : 0 ～ 500 kHz magnetic shield (4-layer) ・ permalloy Solenoid coil (static field) ・ B 0 = 30.6 mG (I = 7.354 mA) spin precession signal 129 Xe : 230 torr N 2 : 100 torr Rb : ~ 1 mg Pyrex glass SurfaSil coating 129 Xe gas cell 18 mm

19. Spin polarization of 129 Xe and Optical detection of nuclear precession Spin polarization of 129 Xe Detection of precession of 129 Xe D1 line ： 794.7 nm 129 Xe Rb 129 Xe N2N2 N2N2 Rb 129 Xe Rb Xe Circular polarization (modulated by PEM) RbXe Rb Xe Probe laser beam : single mode diode laser (794.7nm) Transverse polarization transfer : 129 Xe nuclei → Rb atoms (re-pol) Spin-echange in Rb-Xe Optical pumping Rb atom After half-period precession B0B0 Detector

20. Spin oscillator Realization of maser oscillation at very low fields (  mG) Suppression of drifts in the B 0 field => Suppression of drifts in “Optically coupled” spin maser with a feedback field generated according to optical spin detection P(t)P(t) B(t)B(t) B0B0 0 P(t)P(t) Feedback torque Pumping and relaxation effect Static magnetic field : B 0  mG Pumping light Photo diode Feedback coil Probe light Feedback circuit Lock-in detection precession signal Feedback system ② Optical detection of the spin precession ① 129 Xe nuclear spin polarization by optical pumping ③ Generation of a feedback field ④ Self-sustained spin precession

21. Probe Laser (DL-DFB) PEM Array-type Laser Mirror Glan Laser prism Fiber-coupled Laser Heater Magnetic Shield Ookayama Campus, Tokyo Inst. of Technology, Tokyo, Japan

23. Frequency determination Time [rad] Phase [rad] Lock-in Amplifier output Δa = 9.3  10 -9 Hz freq. precision Time [s] Signal [V] VXVX VYVY ・ Phase fitting function ・ Lock-in amplifier output signals ν ref Reference frequency ν 0 Xe precession freq. Lock-in amplifier PhotoDiode detector Function Generator 35Hz 35.1Hz Rb Xe XeXe B0B0 Result

24. [From; T. Inoue et. al., Poster, INPC2010]

25. Long term stability of the oscillation frequency Solenoid current 129 Xe cell temperature Frequency time (0 - 30,000 sec)

26. At present, there are a number of concerns: ・ Do imperfections in spin detection, signal processing, feedback field generation,... affect the oscillation frequency? ・ Does the presence of Rb atoms interfere the measurement? ・ Does the low frequency operation really help in reducing the spourious drifts? These should be tested and investigated by using actual setup.

27. Frequency pulling effect Simulation Expt. ●A phase deviation  in the feedback field will induce a shift in the Maser frequency.

28. Ongoing developments ・ Pumping laser ・ Double cell ・ B 0 stabilization ・ Simulation study ・ Magnetometry B || φ fitting Paraffin coating z z 0.0 -2.0 -4.0 -6.0 2.04.06.0 0.0 0.2 0.4 0.6 -0.2 -0.4 -0.6 In paraffin coated cell NMOR magnetometry [Tsuchiya et al.] [Hayashi et al.] [Furukawa et al.] [Inoue et al.] [Nanao, Yoshimi et al.] [M. Tsuchiya,... ] [T. Furukawa,... ] [H. Hayashi, T. Furukawa,... ] [T. Nanao, A. Yoshimi,... ] [T. Inoue,... ]

29. HV application system preparation - Cubic cell size : 20 mm × 20 mm × 20 mm Pyrex glass (corning 7740) - Transparent electrode : ITO (Indium Tin Oxide) transmittance ~ 85%@795 nm size : 30 mm × 30 mm × 1.75 mm resistance : ~ 30  High voltagePicoammeter Transparent electrode Xe cell for an E-field a trial piece HV A Cell R : 1 M  C : 2 nF Protection circuit for picoammeter Leakage current test HV [kV] Leakage current [nA] preliminary spark [T. Inoue,... ]

30. HV application system preparation Next step… - Smaller cell (10 mm gap) - Using 2 high voltage source (positive and negative) - N 2 or SF 6 gas atmosphere - Low pass filter for reducing the noise output by HV source …

31. 300nA, ~40ppm 1.5mHz ~40ppm Current fluctuation Fluctuation of Xe precession Frequency instability : mostly due to current fluctuation In magnetic shield: ~28 mG magnetic field with a solenoid coil & stabilized current source (applying 7mA current) Current instability = magnetic field fluctuation → Frequency instability Magnetic field stabilization

32. Previous current source - stabilized current source drift : <50nA in a few hour - slow & large drift (up to 1uA) in long-term operation Current source ~ 7 mA

33. Using an accurate voltmeter with a reference resistance to obtain high resolutions Two current sources are installed in parallel for setting resolutions Feedback of current fluctuation (measured with Dig. Voltmeter) to correct the current drift Current source 1 ~ 6.5 mA Current source 2 ~ 0.5 mA Digital Voltmeter Feedback A new current supply system

34. Stability improved ! Fluctuation:<1/200 This fluctuation is mainly due to the accuracy of current measurement. Conclusion: The current stability is improved successfully (x200) with the feedback of current fluctuation. stability – limited by accuracies of current measurement Future : More accurate measurement of current drift → More stabilized magnetic field for EDM measurement Performance of new current source

35. Future Spherical cell ・ good symmetry ・ Reflection ⇒ lowering of the pumping efficiency? Cubic cells DFB Laser Diode Optical Isolator Taper Amplifier Introduction of a narrow-line laser (TA DFB, TOPTICA) Power : ~ 430 mW line width : ~ 4MHz (cf. pressure broadening ~ 7.5 GHz) 20 times enhanced pumping efficiency => suppression of amplitude fluctuations

36. Setup ポンピング部分 ( 偏極生成部分 ) 偏極度測定部分 Double cell for 129 Xe gas 偏極度測定装置 129 Xe : 227torr N 2 : 133torr Rb パイレックスガラス SurfaSil コーティング RF coil pick-up coil ポンピング レーザー 保持磁場用 コイル

37. Cell test bench ・ Incorporation of anti-vibration system ・ Orthogonality adjustment mechanism for pick-up coil ・ Incorporation of anti-vibration system ・ Orthogonality adjustment mechanism for pick-up coil High-precision, high-reproducibility assesment system for 129 Xe cells trim coil pick-up coil material ： PEEK pick-up coil 固定されていない → 測定の再現性が低い, 調整が困難, 振動に弱い pick-up coil が振動 →NMR シグナルと同じ周波数である RF シグナルを検出 → ノイズの発生 pick-up coil 固定されていない → 測定の再現性が低い, 調整が困難, 振動に弱い pick-up coil が振動 →NMR シグナルと同じ周波数である RF シグナルを検出 → ノイズの発生 New system Current problems

38. Simulation study of the frequency precision Incorporate the phase and amplitude fluctuations of the maser signal. A : シグナル振幅 ε : 振幅のゆらぎ Time [s] Signal [V] Time [s ] Phase deviation[rad] Time [s] Phasedeviation[rad] ν ：測定周波数 φ fluc ：位相ゆらぎ φ peri ：周期変動

39. Frequency Precision[Hz] Time [s] Simulation results Should reach a 10 -10 Hz precision in a 2-day measurement !! 2.3 ｘ 10 -10 Hz 6.7 ｘ 10 -11 Hz 2.0x10 -11 Hz Experiment  A,     ≈ the experiment  A   ≈ the experiment,   peri ≈  0.5  A,     ≈  1/10 ← 1.9x10 -30 ecm (E=10kV) 12days1day Half a day Simulation

40. Magnetometry ； Non-linear MagnetoOptical Rotation ( NMOR ) on Rb atoms k Linear polarized light Rb atom B Resonant optical rotation in Rb vapor (NMOR; Nonlinear Magneto-Optical Rotation) D. Budker et al.,PRA 62 (2000) 043403. Optical Pumping magnetometers (Rb, Cs)： 30 pG/ √Hz Magnetometry with SQUID ： 2-3 fT/ √Hz = 20-30 pG / √Hz @ He temp. 50-60 fT/ √Hz = 0.5 – 0.6 nG/ / √Hz @ liq. N 2 temp. High-Q resonator → 0.08 fT/ √Hz = 0.8 pG / √Hz Advantages: Narrow width Operation at room temp. low field x z y B +E +t+t Required frequency precision Field precision required in EDM measurements @ E=10kV/cm Field

41. m F = -1m F = 0m F = +1 gBgB ++  - (F’=0) (F=1) 1) 直線偏向光 により原子は alignment 状態になる → 原子集団の蒸気は linear dichroism を持つ 2) 原子 alignment が磁場の周りを歳差運動する → dichroism の軸が回転する 3) 回転する dichroic 軸を持つ原子と入射直線偏光ビームとの 相互作用で偏光面が回転する 原理 NMOR 直線偏向光と原子の相互作用 右・左円偏向成分に対する原子系屈折率 直線偏向面の回転 -10 -5 0 5 10 0.6 0.4 0.2 0.0 -0.2 -0.4 -0.6 Rotation angle (mrad) 基底状態

44. Summary ● Precession of 129 Xe spins is maintained for unlimitedly long times, by application of a feedback field generated from optically detected spins. The merit of this optically coupled spin maser as a scheme for the EDM search is the capability of operation at very low B 0 fields, as mG or below. ● Frequency precision presently reached is 9.3 nHz, which corresponds to an EDM sensitivity of 9  10 -28 ecm (E=10kV/cm). ● There still remain drifts/fluctuations in the maser frequency that are correlated with ambient temperature and noises. Improvements and further developments are under progress. ・ Reinforcement of 129 Xe polarization by introducing a narrow-line high-power TA-DFB pumping laser ・ Stabilization of solenoid current ・ Stabilization of cell temperature by means of a heat transfer fluid GALDEN ・ Cell development for the E-field application ・ Magnetometry with NMOR, aiming at detection of d( 129 Xe) in a 10  28 -10  29 ecm regime.