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. Asahi1

1 Tokyo Institute of Technology, Meguro-ku, Tokyo 152-8551, Japan2 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 129Xe 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

s

+ ++-

--+

-

+q

-q

a = d ≡ qa

Electric Dipole Moment (EDM) d

3

particle( ) dd r r ror,

5EDM 2

id F

L

or,

Electric Dipole Moment

1. Introduction

Eext

(Permanent) Electric Dipole Moment

+ ++

= 0

Electric dipole moment (EDM)Electric dipole moment (EDM)

time reversal time reversal s →→ -sd →→ d

spinspinEDMEDM

::::

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.

Electric dipole moment (EDM)Electric dipole moment (EDM)

time reversal time reversal s →→ -sd →→ d

spinspinEDMEDM

::::

s

-- -

++ +

d s

-- -

++ +

d

d ≠ 0 ： ： Violation of T ⇒ Violation of CP (CPT theorem)

Sites of EDM searches• neutron dN

• paramagnetic atoms (Tl, Fr, Cs, ...) de

• diamagnetic atoms (129Xe, 199Hg, Rn, Ra, ...) S

• molecules (TlF, YbF, PbO, ThO, ...) de

• charged particles (d, , ...) dN, d

⇒ Probing different facet ｓ of anticipated new physics

Electric dipole moment (EDM)Electric dipole moment (EDM)

time reversal time reversal s →→ -sd →→ d

spinspinEDMEDM

::::

s

-- -

++ +

d s

-- -

++ +

d

d ≠ 0 ： ： Violation of T ⇒ Violation of CP (CPT theorem)

Tl, Fr, Cs… 129Xe, 199Hg, Rn, Ra…

M. Pospelov and A. Ritz,Annals of Phys. 318, (2005) 119-169

EDM in 129Xe atoms

•stable particle•macroscopic number of particles•EDM generated by a nuclear

Schiff moment•P,T-violating NN interaction

Schiff moment

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

Nucleus

Electron cloud

Nontrivial charge distribution in the nucleus generates an EDM in atom:

Schiffatom

0

ˆ0 0 ˆ2 , where iP iP

P P ee

E E

D

d D R

Schiff 4 ( ) S R

2 2 3

nucleus

1 5( ) d

10 3r r S r r r Schiff moment

d(129Xe) = 3.8×105 fm2 ·S(129Xe)

d(199Hg) = 2.8×104 fm2 ·S(199Hg)

datom ≠0

Nucleus

Electron cloud

[Ginges & Flambaum, Phys. Rep. 397 (04) 63]

What generates a Schiff moment ?

199 (0) (1) (2) 3( Hg) 0.0010 0.074 0.018 fmNN NN NN NN NN NNS g g g g g g e

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 199Hg

●Case of 129Xe 　　　 Flambaum, Khriplovich, Sushkov, 1985 Dzuba, Flambaum, Porsev, 2009 Yoshinaga's group, consideration fro shell model in progress.

(0)u d

(1)u d

,NN

NN

g d d

g d d

d(129Xe) < 4.1×10-27 ecmRosenberry and Chupp, PRL 86 (2001) 22

d(199Hg) < 3.1×10-29 ecm

Grifith et al., PRL 102 (2009) 101601Standard Model(dn = 10-(31-33) )

Neutron EDM predicted values

d = 1027 　 e·cmE = 10 kV/cm

　 = 10 nHz（ 1°/day ）

[Pendlebury and Hinds, NIM A 440 (00) 471]

dEBH E // B

dEBH E // B

Energy shift upon an E-field reversal

Shift in a precession frequency

h

dEB 22

)//( BEh

dEB 22

)//( BE

the difference 　⇒　 signal of an EDM

EdBμ H

2

1m

2

1m

0

0

E

B

0h h hν

BE

B

//

0BE

B

//

0

0

0

E

B

B E

s

B E

s

Energy levels for a spin 1/2(for a case of > 0, d > 0)

h

E 4 d

Detection of an EDMDetection of an EDM

Desires long precession times => Spin maser

― Realization of a long precession time

Key issue for a high-sensitivity EDM detection:

Free precession

TimeTra

nsve

rse

spin ‘Spin maser’ state

TimeTra

nsve

rse

spin

02

02

01

d,

d

d,

d

d.

d

x xy z y

y yz x x

z zx y y x z

P PP B P B

t T

P PP B P B

t T

P PP B P B P P G

t T

Spin maser

B

● 129Xe polarization vector P = I/I

● Static field B0 = (Bx, By, B0)

1,2

1

T P B P P

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,

02

02

01

d,

d

d,

d

d.

d

x xy z y

y yz x x

z zx y y x z

P PP B P B

t T

P PP B P B

t T

P PP B P B P P G

t T

Spin maser

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),

( ) ( )

( ) ( )

x y

y x

B t P t

B t P t

Taking (1) + i (2) and setting

02

2

01

d 1, (4)

d

d. (3')

d

z

z zz

PP P

P P

it T

P PP Gt T

( ) ( ) ( )i tx yP t iP t e P t

The steady state solutions

　・ Trivial solution:

　・ Non-trivial solution:

d d0 and 0 .

d d zP P

t t

eq eq 10

1

0, 1z

GTP P P

GT

eq eq10 0

2 2

1 1/ 1, , with = .z

GTGP P P

T T

02

02

01

d, (1)

d

d, (2)

d

d. (3)

d

xy z

y yx z y

z zx x y

xx

y z

t T

t T

P Gt T

P PP P P

P PP P P

P PP P P P P

0 0

x y

y x

B P

B P

B

02

02

01

d,

d

d,

d

d.

d

y

x

y x

x xy z

y yz x

z zx y z

P PP B P

t T

P PP P B

B

B

B B

t T

P PP P P P G

t T

Spin oscillator

B(t)

● Now we devise the transverse part of the B field, B(t), to follow P

( ) ( )

( ) ( )

x y

y x

B t P t

B t P t

B(t)

Spin detection

steady oscillationtransient

Maser oscillation

Setup for the maser experimentSetup for the maser experiment

Probe laserProbe laser・ DFB laser・ = 794.76 nm (Rb D1line)・ = 8.4×10-6 nm・ Power : 15 mW

Pumping laserPumping 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)・ B0 = 30.6 mG (I = 7.354 mA)

0B

C70T

spin precession signal

129Xe : 230 torrN2 : 100 torr Rb : ~ 1 mgPyrex glass

SurfaSil coating

129Xe gas cell

18 mm

Spin polarization of 129Xe and Optical detection of nuclear precession

Spin polarization of 129Xe Detection of precession of 129Xe

2

1sm

2

1sm

2/1P5

2/1S5

D1 line ： 794.7 nm

IS

129Xe

Rb

Rb

129Xe

N2

N2

129Xe Rb

Rb 129Xe

Rb

Xe

Xe Xe

Circular polarization(modulated by PEM)

RbXe

Xe

Xe

RbXe

Probe laser beam : single mode diode laser (794.7nm)

Transverse polarization transfer : 129Xe nuclei → Rb atoms (re-pol)

Spin-echange in Rb-Xe

Optical pumping Rb atom

After half-period precession

B0

Detector

Spin oscillatorSpin oscillator

Realization of maser oscillation at very low fields ( mG)Suppression of drifts in the B0 field => Suppression of drifts in

“Optically coupled” spin maserwith a feedback field generated according to optical spin detection

P(t)

B(t)

B0

0

P(t)

Feedback torque

Pumping and relaxation effect

Static magnetic field : B0 　 mG

Pumping light

Photodiode

Feedback coil

Probe light Feedbackcircuit

Lock-in detection

precession signal

Feedback system

② Optical detection of the spin precession

①129Xe nuclear spin polarizationby optical pumping

③Generation of a feedback field

④Self-sustained spin precession

Probe Laser(DL-DFB)

PEMArray-type

Laser

Mirror

Glan Laserprism

Fiber-coupledLaser

HeaterMagnetic Shield

Ookayama Campus,Tokyo Inst. of Technology,Tokyo, Japan

Frequency determination

Time [rad]

Pha

se [

rad] bxaxf 2)(

)(

)(tan)( 1

tV

tVt

X

Y

Lock-in Amplifier output

Δa = 9.310-9 Hz freq. precision

Time [s]

Sig

nal [

V]

VX VY

・ Phase

fitting function

))()(2sin(

))()(2cos(

0ref0ref

0ref0ref

tV

tV

Y

X

・ Lock-in amplifier output signals

νref Reference frequencyν0 Xe precession freq.

Lock-in amplifier

PhotoDiodedetector

FunctionGenerator

refout 0ref

0

35Hz

35.1HzRb

Xe

Xe

Xe

B0

Xe

Result

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

Long term stability of the oscillation frequency

Solenoid current

129Xe cell temperature

Fre

quen

cyF

requ

ency

time (0 - 30,000 sec)

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.

Frequency pulling effect

Simulation

Expt.●A phase deviation in the feed

back field will induce a shift in the Maser frequency.

0

2

tanT

zi

i

z

PeiT

tPeitB

tBtPiiT

tPdt

d

02

TT

T02

T

1

)()(1

)(

Ongoing developments

・ Pumping laser

・ Double cell

・ B0 stabilization

・ Simulation study

・ Magnetometry

B||

φ

fitting

Paraffin coating

z

z 0.0-2.0-4.0-6.0 2.0 4.0 6.0

0.0

0.2

0.4

0.6

-0.2

-0.4

-0.6

NMOR magnetometry

15

0

4 10 GB

dB

dB

[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, ... ]

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-fielda trial piece

HV

A

Cell

R : 1 MR : 1 M

C : 2 nF

Protection circuit for picoammeter

Leakage current test

HV [kV]

Lea

kage

cur

rent

[nA

] preliminary

spark

[T. Inoue, ... ]

HV application system preparation

Next step…- Smaller cell (10 mm gap)- Using 2 high voltage source (positive and negative)- N2 or SF6 gas atmosphere- Low pass filter for reducing the noise output by HV source …

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

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

Using an accurate voltmeter with a reference resistanceto obtain high resolutions

Two current sourcesare installed in parallelfor 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

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

FutureFuture

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 mWline width : ~ 4MHz(cf. pressure broadening ~ 7.5 GHz)

20 times enhanced pumping efficiency

=> suppression of amplitude fluctuations

-17 sec 10~

SetupSetup

ポンピング部分(偏極生成部分 )

偏極度測定部分Double cell for 129Xe gas

偏極度測定装置

129Xe : 227torrN2 : 133torr

Rbパイレックスガラス

SurfaSil コーティング

RF coil

pick-upcoil

ポンピングレーザー

保持磁場用コイル

Cell test benchCell 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 129Xe cells High-precision, high-reproducibility assesment system for 129Xe 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

Simulation study of the frequency precision

Incorporate the phase and amplitude fluctuations of the maser signal.

periflucnn

x

t

tAA

A

2

)(

sinV

1

0

A : シグナル振幅ε : 振幅のゆらぎ

Time [s]

Sig

nal [

V]

Time [s]

Pha

se d

evia

tion

[rad

]

Time [s]

Pha

sede

viat

ion[

rad]

ν ：測定周波数φfluc ：位相ゆらぎφperi ：周期変動

Fre

quen

cy P

reci

sion

[Hz]

Time [s]

Simulation results

Should reach a 10-10 Hz precision in a 2-day measurement !!

2.3 ｘ 10-10 Hz6.7 ｘ 10-11 Hz2.0x10-11 Hz

Experiment

A , ≈ the experiment

A ≈ the experiment, peri ≈ 0.5A , ≈ 1/10

←1.9x10-30 ecm(E=10kV)

12days1dayHalf a day

periflucnn

x

t

tAA

A

2

)(

sinV

1

0

Simulation

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.

HzpG/1~B

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. N2 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

Required frequency precision

Field precision required in EDM measurements

cm10~ -28 ed A@ E=10kV/cm

nHz1f

pG1BField

mF = -1 mF = 0 mF = +1

gB

+ -

(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

00

00 2

21

iBg

nzBF

直線偏向光と原子の相互作用

0

2

0

0

221

2

2 l

l

Bg

Bg

nnl

zBF

zBF

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

-0.60

B2

zF Bg

Ro

tatio

n a

ng

le (

mra

d)

00

112

1

112

1

F

FF

FF

m

mm

mm

基底状態

Summary

● Precession of 129Xe 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 B0 fields, as mG or below.

● Frequency precision presently reached is 9.3 nHz, which corresponds to an EDM sensitivity of 910-28 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 129Xe 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(129Xe) in a 1028 -1029 ecm regime.