Single-atom Optical Clocks— and Fundamental Constants

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Single-atom Optical Clocks— and Fundamental Constants Hg+ clock Brent Young Rob Rafac Sebastien Bize Windell Oskay Luca Lorini Anders Brusch Sarah Bickman fs-comb (Ti:Sapphire) Tara M. Fortier Jason E. Stalnaker Thomas Udem Scott A. Diddams Leo Hollberg fs-comb (fiber) Ian Coddington William C. Swann Nate R. Newbury Al+ clock Till Rosenband David B. Hume C.-W. Chou P. O. Schmidt Jim Bergquist Till Rosenband Wayne Itano Dave Wineland NIST- F1 Steve Jefferts Tom Heavner Elizabeth Donley Tom Parker JILA Jun Ye Jan Hall et al…

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Single-atom Optical Clocks— and Fundamental Constants. Jim Bergquist Till Rosenband Wayne Itano Dave Wineland. Al+ clock Till Rosenband David B. Hume C.-W. Chou P. O. Schmidt. Hg+ clock Brent Young Rob Rafac Sebastien Bize Windell Oskay Luca Lorini Anders Brusch Sarah Bickman. - PowerPoint PPT Presentation

Transcript of Single-atom Optical Clocks— and Fundamental Constants

Page 1: Single-atom Optical Clocks— and Fundamental Constants

Single-atom Optical Clocks—and Fundamental Constants

Hg+ clockBrent YoungRob Rafac

Sebastien BizeWindell Oskay

Luca LoriniAnders BruschSarah Bickman

fs-comb (Ti:Sapphire)Tara M. Fortier

Jason E. StalnakerThomas Udem

Scott A. DiddamsLeo Hollberg

fs-comb (fiber)Ian Coddington

William C. SwannNate R. Newbury

Al+ clockTill RosenbandDavid B. Hume

C.-W. ChouP. O. Schmidt

Jim BergquistTill Rosenband

Wayne ItanoDave Wineland

NIST- F1Steve JeffertsTom Heavner

Elizabeth DonleyTom Parker

JILAJun Ye

Jan Hallet al…

Page 2: Single-atom Optical Clocks— and Fundamental Constants

What is a clock?

Period

Frequency

An Oscillator(Generates periodic events)

A Counter(Count and display events

/ tell time)

~~~~

Page 3: Single-atom Optical Clocks— and Fundamental Constants

What Makes a Clock a Time Standard?

Requirements:

Stability: Δti = Δtj or /t 0

Accuracy: Δt the same for all clocks 0

Added Ingredient

Stable, “unperturbed” reference

Page 4: Single-atom Optical Clocks— and Fundamental Constants

Optical Clock

Laser Oscillator

Single Ion/Neutral Atoms

Femtosecond comb

14:46:32

State detector

Frequencyfeedback

1121 THz

Drive atomicresonance

Count optical cycles

Clock frequency:

Clock shift: anything that shifts (E2-E1)

Page 5: Single-atom Optical Clocks— and Fundamental Constants

Why Use Optical Transitions?

Quantum Limit: Δ/ (20)-1(NTR)-1/2

0 = transition frequency of reference (usually atom or molecule)

N = # of atoms TR = interrogation time = averaging time

Examples:

Cs fountains:0 = 9.2 GHz, N 106, TR 1 s Δ/ 410-14 -1/2

Single Atom: 0 = 1015 Hz, N 1, TR 30 ms

Δ/ 110-15 -1/2

Page 6: Single-atom Optical Clocks— and Fundamental Constants

Electron Shelving H.G. Dehmelt, Bull. Amer. Phys. Soc. 20, 60 (1975)

Gives method to detect weak transition in single atom

1 11 << 2

0

2 2

The absorption of one photon on the weakly allowed transition to level 2

shuts off the scattering of many photonson the strongly allowed transition to level 1

Page 7: Single-atom Optical Clocks— and Fundamental Constants

199Hg+ Energy Levels

3

• Atomic line • State detection by electron shelving.

Page 8: Single-atom Optical Clocks— and Fundamental Constants

Ground stateExcited state

0 200 400 600 800Time (ms)

0

20

40

60

80

Cou

nts/

ms

Quantum Jump Spectroscopy

9

The mercury ion acts asa *noiseless* optical amplifier

One absorption event can preventmillions of scattering events

Page 9: Single-atom Optical Clocks— and Fundamental Constants

Isolated Cavities

Page 10: Single-atom Optical Clocks— and Fundamental Constants

Isolated Cavities

• Resonancesnear 0.3 Hz

• Servo table heightby heating legs

• Two independentcavity systems

Page 11: Single-atom Optical Clocks— and Fundamental Constants

frequency (Hz)

Rela

tive b

eatn

ote

pow

er

(arb

.) 0.22 Hz

Beatnote between laser sources stabilized to independent cavities

15

Page 12: Single-atom Optical Clocks— and Fundamental Constants

Mounted Spherical Cavity

Orientation insensitive

Page 13: Single-atom Optical Clocks— and Fundamental Constants

“Magic” Mounting Angle of Spherical Cavity

• Captured cavity:• Changing stress from mount points

shifts cavity frequency– 1°C 1 m 0.02 lb 300 kHz

• Vertical mount points:– Squeeze makes cavity longer

• Mount near optical axis:– Squeeze makes cavity shorter

• At 37 degrees: zero sensitivity• Symmetry vibration insensitivity

-60

-50

-40

-30

-20

-10

0

10

20

0 10 20 30 40 50 60 70

Angle [deg]

Sq

ue

eze

se

ns

itiv

ity

[M

Hz/

lb]

No movement

Page 14: Single-atom Optical Clocks— and Fundamental Constants

3-D Vibration sensitivity

v-block mounted cylindrical cavity

Spherical cavity(measured)

NPL, 2008

SYRTE, 2009

Page 15: Single-atom Optical Clocks— and Fundamental Constants

Vibration-broadened laser power-spectrum (predicted)

CylinderSphere

Linear scale

Las

er p

ow

er s

pec

tru

m a

t 25

0 T

Hz

[dB

]

Page 16: Single-atom Optical Clocks— and Fundamental Constants

• No static E or B fields; Trap acts on total charge of ion,

not internal structure

21

• Trap ion at trap center wheretrapping fields approach zero

• Motion in trap: Micromotion at trap frequency, slow harmonic “secular” motion

Trapped ions in an rf trap

10

~ rf

Page 17: Single-atom Optical Clocks— and Fundamental Constants

11

• Can operate in tight-confinement (Lamb-Dicke) regime ⇒ First-order doppler free.

2nd-order doppler shift (time dilation) due to micromotion will limit accuracy

• No static E or B fields; Trap acts on total charge of ion,

not internal structure

• Trap ion at trap center wheretrapping fields approach zero

Trapped ions in an rf trap

~ rf

Page 18: Single-atom Optical Clocks— and Fundamental Constants

12

Cryogenic iontrap system

Magnetic Shield

Page 19: Single-atom Optical Clocks— and Fundamental Constants

Cryogenic iontrap system

12

Magnetic Shield

Cryostat Wall

Page 20: Single-atom Optical Clocks— and Fundamental Constants

Cryogenic iontrap system

12

Magnetic Shield

Cryostat Wall

77 K Shield

Page 21: Single-atom Optical Clocks— and Fundamental Constants

Cryogenic iontrap system

12

Magnetic Shield

Cryostat Wall

77 K Shield

4 K Copper Shieldaround trap

Page 22: Single-atom Optical Clocks— and Fundamental Constants

13

Helical Resonator

Magnetic Shield

Cryostat Wall

Liquid Nitrogen

Liquid Helium77 K Shield

4 K Copper Shieldaround trap

• Long storage times

• Environmental isolation- Low collision rate- Low blackbody

Page 23: Single-atom Optical Clocks— and Fundamental Constants

13

Page 24: Single-atom Optical Clocks— and Fundamental Constants

0.8 mm

14

Trap material: molybdenum

Page 25: Single-atom Optical Clocks— and Fundamental Constants

Spectroscopy of 199Hg+

• Accessible strong transition for laser-cooling, state preparation/detection

• Large mass ↔ small 2nd order Doppler shift

• static quadrupole shift can be minimized

• small blackbody shift

• 1.8 Hz linewidth clock transition

Page 26: Single-atom Optical Clocks— and Fundamental Constants

Some facts about Al+

• 8 mHz linewidth clock transition

• Small quadratic ZS (6x10-16 /Gauss2)

• Negligible electric-quadrupole shift (J=0)

• Smallest known blackbody shift (8x10-18 at 300K)

• Linear ZS 4 kHz/Gauss (easily compensated)

• Light mass (2nd order Doppler shifts)

• No accessible strong transition forcooling & state detection

1S0

167 nm

1P1

3P0

267 nm1121 THz

I = 5/2

Page 27: Single-atom Optical Clocks— and Fundamental Constants

Clock state transfer to Be+

1. Cool to motional quantum ground state with Be+

2. Depending on clock state, add vibrational energy via Al+

3. Detect vibrational energy via Be+

(simplified)

Page 28: Single-atom Optical Clocks— and Fundamental Constants

Using two ionsClock ion (Al+) for very accurate spectroscopyLogic ion (Be+) for cooling and readoutCoulomb-force couples the motion of the ions Cooling Be+ leads to cooling of Al+Ion motion is quantized (n=0, 1, …)Transfer information Al+ Motion Be+

Page 29: Single-atom Optical Clocks— and Fundamental Constants

Quantum Logic Spectroscopy

3P1=300s

1S0

267.0 nmClock transition267.5 nm

Clock laserpulse

Transitionoccurred?

1S0, n = 0

3P1 blue side-band pulse

yes

3P0, n = 0

no

3P1 blue side-band pulse

3P1, n = 1

27Al+n = 1n = 0

n = 1n = 0

n = 1n = 0

P.O. Schmidt, et al.Science 309, 749 (2005)

T. Rosenband, et al. PRL 98, 220801 (2007)

D.B. Hume, et al. PRL 99, 120502 (2007)

3P0, n = 0 1S0, n = 0

3P0

Page 30: Single-atom Optical Clocks— and Fundamental Constants

Single phonon detection

9Be+

Red side-band pulse

Red side-band pulse

2S1/2 F=2n = 0

2S1/2 F=1n = 0

Detection pulse

Detection pulse

~ 4-10in 200 s

~ 1in 200 s

27Al+ 3P0

n = 0

27Al+ 1S0

n = 1

9Be+ 2S1/2 F=2n = 0

9Be+ 2S1/2 F=2n = 1 2P3/2 F=3

2S1/2 F=2

313 nmCooling /detection

Red sideband pulse 1.2 GHz

Pho

toncounter

2S1/2 F=1

n = 1n = 0

n = 1n = 0

Page 31: Single-atom Optical Clocks— and Fundamental Constants

-10 -5 0 5 100

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0.9

1

Frequency offset [Hz] near 1121 THz

Tra

nsiti

on p

rob.

Al+ 1S0 - 3P

0 resonance (20 scans, 250 ms probe time)

3.2 Hz

Q = 3.5 x 1014

High quality transition

C.-W. Chou

Page 32: Single-atom Optical Clocks— and Fundamental Constants

fiber

fiber

fb,Al

m frep+ fceo

1070 nmlaser

×2

×2

×2

×2

fb,HgHg+

n frep+ fceo

199Hg+

27Al+

9Be+

1126 nmlaser

Al+/Hg+ Comparison fs-comb locked to Hg+ measure beat with Al+

Page 33: Single-atom Optical Clocks— and Fundamental Constants

Pump laser

Pulse duration: Repetition rate:

23

Femtosecond Ti:Sapphire Laser

Pulsed output

Page 34: Single-atom Optical Clocks— and Fundamental Constants

• Other optical standards (Al+, Ca, Yb, Sr, etc.) Difference frequency:

• Microwave standards Difference frequency:

33

Laser frequency (563 nm):

Interclock comparisons:

Problem:Fastest electronic counters:

Counting optical frequencies

Solution:Femtosecond laser frequency comb

Page 35: Single-atom Optical Clocks— and Fundamental Constants

Dec Jan FebMar Apr May Jun Jul Aug Sep Oct Nov Dec

0.4

0.5

Al/

Hg

10

15 -

1 0

52

87

1 8

33

14

8 9

90

-dot / = (1.433 +/- 1.702) x 10-17 / yr 2 =2.9674

2006 20072007

Al+/Hg+ Comparison

10-16

νAl+/νHg+ = 1.052 871 833 148 990 438 ± 55 x 10-17

Page 36: Single-atom Optical Clocks— and Fundamental Constants

Al+/Hg+ Stability

100

101

102

103

104

105

10-17

10-16

10-15

10-14

Al+ vs Hg+, 11874 seconds total

3.9*10-15 * ( / s)-1/2

Al+ vs Hg+ ADEVAl+ vs Hg+ THEO1

3.6 x 10-17

In 3 hours!

Averaging time [s]

Fre

quen

cy r

atio

unc

erta

inty

Page 37: Single-atom Optical Clocks— and Fundamental Constants

Dec Jan FebMar Apr May Jun Jul Aug Sep Oct Nov Dec

0.4

0.5

Al/

Hg

10

15 -

1 0

52

87

1 8

33

14

8 9

90

-dot / = (1.433 +/- 1.702) x 10-17 / yr 2 =2.9674

2006 20072007

Al+/Hg+ Comparison

10-16

Page 38: Single-atom Optical Clocks— and Fundamental Constants

Transition Frequencies

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V. A. Dzuba, V. V. Flambaum, and J.K. Webb,PRA 59, 230 (1999)E. J. Angstmann, V. A. Dzuba, and V. V. Flambaum PRA 70, 014102 (2004)

Express transition frequencies as:

Page 39: Single-atom Optical Clocks— and Fundamental Constants

-10

0

10

Hg

- 1

064

721

609

899

145.

33 (

Hz)

Jan 01 Jan 02 Jan 03 Jan 04 Jan 05 Jan 06

Measurement Date

Historical Record of νHg

28 Measurements

• Aug. 2000 - Mar. 2004: (23) with realistic assumption uncertainty in quadrupole shift < 1 Hz.

• Oct. 2004 - Jan 2005: (3) Uncertainty due to measurement statistics and Hg+ systematics are approximately equal

• July 2005 - present: (2) Uncertainty dominated by measurement statistics

•Fit to a line: (∂ν/∂t)ν=(0.36 ± 0.39)×10-15/yr implies-

(∂α/∂t)/α = (6.2 ± 6.5) × 10-17/yr if ∂(lnμ/μB)/∂t = 0

Page 40: Single-atom Optical Clocks— and Fundamental Constants
Page 41: Single-atom Optical Clocks— and Fundamental Constants

Constraint on Cs/B

-1.0 -0.5 0.0 0.5 1.0-10

-5

0

5

10

d/d

t ln( C

s/B)

x 1

0-16

d/dt ln() x 10-16

/ x 10-16 = (-3.1 +/- 3.9) x 10-16 / year

Hg+ vs. CsT. Fortier et al.PRL 98, 070801

Hg+ vs. Al+

Science

CsB

Page 42: Single-atom Optical Clocks— and Fundamental Constants

…..[the Hg+ ion] clock is so powerful yet so exquisitely fine-tuned that it virtually echoes the ionic heartbeat of the universe itself. And so precise that it is accurate to within seconds per month.

Direct-mail copy writers

Page 43: Single-atom Optical Clocks— and Fundamental Constants

Outlook

• Keep measuring Al+/Hg+

• Compare with other standards

• Variation of fundamental constants?

• Solid state lasers

• Second Al+ and Hg+ clock?

• More Al ions

• More Hg ions

Page 44: Single-atom Optical Clocks— and Fundamental Constants

“…the most important unit of time?”

“A Lifetime.”

Howard Bell (~1980)