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Stable & Accurate Single- - Stable & Accurate Single atom - - PowerPoint PPT Presentation

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Stable & Accurate Single- - Stable & Accurate Single atom Optical Clocks atom Optical Clocks Ti:Saph Fs-comb group: The Masters: Al+ Ion Group: Jason Stalnaker Wayne Itano Tara M. Fortier Till Rosenband Dave Wineland Kyoungsik

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SLIDE 1

Stable & Accurate Single Stable & Accurate Single-

  • atom Optical Clocks

atom Optical Clocks

Al+ Ion Group:

Till Rosenband Piet Schmidt* James Chou David Hume

Cs Clock Group:

Steve Jefferts Tom Heavner Liz Donley Tom Parker

* funded by:

Ti:Saph Fs-comb group:

Jason Stalnaker Tara M. Fortier Kyoungsik Kim Scott A. Diddams Leo Hollberg

Fiber Fs-comb Group:

Ian Coddington Bill Swann Nate Newbury

JILA

Jun Ye et al.

The Masters: Wayne Itano Dave Wineland Hg+ Ion Group:

Anders Brusch Luca Lorini Windell Oskay Brent Young Rob Rafac Carol Tanner Robert Drullinger

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SLIDE 2

2

What is a clock?

An Oscillator (Generates periodic events) A Counter (Counts and displays events)

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SLIDE 3

Optical Clock

Laser Oscillator Single Ion/ Neutral Atom fs-comb 10:24am State Detector frequency feedback 1121 THz

Frequency standard

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SLIDE 4

Atom Number: Transition Frequency: Interrogation time:

Expected Stability:

5

Clock stability

Example 1: Cesium fountain clock Example 2: Mercury ion optical clock

Atom Number: Transition Frequency: Interrogation time:

Expected Stability:

  • Higher stability, even with only one atom!

Potentially high accuracy.

Quantum projection noise limit:

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SLIDE 5

Outline

  • Al+/Hg+ clock transitions & spectroscopy
  • Systematic uncertainties
  • Comparisons
  • Implications & future directions
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SLIDE 6

194 nm 194 nm

Laser cooling, detection

282 nm 282 nm

7

Hg Energy Levels

199 +

Metastable state Wide, fast transition Clock reference; Narrow (“forbidden”) transition Quantum Jump spectroscopy (Electron Shelving)

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SLIDE 7

Ground state Excited state 200 400 600 800 Time (ms) 20 40 60 80 Counts/ms

Quantum Jump Spectroscopy

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The mercury ion acts as a noiseless, optical amplifier One absorption event can prevent millions of scattering events

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SLIDE 8

Spectroscopy of 27Al+

Be+ Al+

  • 8 mHz linewidth clock transition
  • Insensitive to external fields
  • Smallest known room temperature

blackbody shift [2]

  • No accessible strong transition for

cooling & state detection

  • Use two-ion quantum logic

techniques with 9Be+ and 27Al+ for cooling, state preparation & readout [1]

Linear Paul Trap

[1] D.J. Wineland et al.,

  • Proc. 6th Symposium on

Frequency Standards and Metrology, 2001, pp. 361-368

1S0

167 nm

1P1 3P0

267 nm

[2] T. Rosenband et al. arXiv:physics/0611125

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SLIDE 9

Normal modes

Center-of-mass (COM) 2.62 MHz

Stretch 5.8 MHz xAl 3.5 MHz xBe 13.0 MHz

Be+ Al+ Linear Paul Trap

z x

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SLIDE 10

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

Clock state transfer to Be+

n=0 n=1 n=0 n=1

Be+ Be+

initial state Al+ 3P1 BSB Be+ RSB detection

Is Al+ in the 1S0 or 3P0 state?

  • 1. Ground state cooling (1 ms)
  • 2. Al+ 3P1 blue sideband (BSB) pulse (30 us)
  • 3. Be+ F=2 → F=1 red sideband (RSB) pulse (7 us)
  • 4. Be+ detection (200 us), record photon counts
  • 5. Al+ 3P1 spontaneous decay

3P1 1S0

F=2 F=1

Al+ Be+

X X X X

  • T. Rosenband, et al.

arXiv:physics/070367 (accepted by PRL)

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SLIDE 11

Detection outcomes

10 20 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 PMT counts P ro b a b ility 10 20 0.02 0.04 0.06 0.08 0.1 0.12 0.14

1S0

Mean = 1.3

3P0

Mean = 6.9 Probability Transitions detected in both directions

99.94% Detection fidelity

  • D. B. Hume, et al.

To be published

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SLIDE 12

1 2 3 4 5 6 7 8 9 10 11 0.5 1 Pulse duration [ms] Transition prob.

  • 20
  • 15
  • 10
  • 5

5 10 15 20 0.2 0.4 0.6 0.8 1 Frequency offset [Hz] near 1121 THz Transition probability 8.4 Hz

Rabi Spectroscopy

100 ms probe time 50 scans

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SLIDE 13

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 where

trapping fields approach zero

Trapped ions in an rf trap

~ rf

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SLIDE 14

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Cryogenic ion trap system

Magnetic Shield

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SLIDE 15

Cryogenic ion trap system

12

Magnetic Shield Cryostat Wall

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SLIDE 16

Cryogenic ion trap system

12

Magnetic Shield Cryostat Wall 77 K Shield

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SLIDE 17

Cryogenic ion trap system

12

Magnetic Shield Cryostat Wall 77 K Shield 4 K Copper Shield around trap

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SLIDE 18

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Helical Resonator Magnetic Shield Cryostat Wall Liquid Nitrogen Liquid Helium 77 K Shield 4 K Copper Shield around trap

  • Long storage times
  • Environmental isolation
  • Low collision rate
  • Low blackbody
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SLIDE 19

13

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SLIDE 20

0.8 mm

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Trap material: molybdenum

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SLIDE 21

Secular Frequency: RF 12 MHz, 1 kV

~

15

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SLIDE 22

16

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SLIDE 23

194 nm

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Cooling, Detection

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SLIDE 24

Fused silica lens in cryostat for state detection

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Cooling, Detection

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SLIDE 25

18

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SLIDE 26

Probe Beam 282 nm

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Clock

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SLIDE 27

Absorption lineshape in 199Hg+

Pg

  • Quantum jump spectroscopy

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  • Lock laser to center
  • f absorption line

6.7 Hz

1.0 0.5

Next: Measure frequency!

  • Single pulse (Rabi)

Excitation

  • Transform-limited

linewidth Probe time:

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SLIDE 28

Al+/Hg+ Comparison

1S0 3P0 27Al+ 2S1/2 2D5/2 199Hg+ [1]

  • fs-comb locked to Hg+
  • measure beat with Al+

fAl/4 fHg/4

[1] W. H. Oskay, et al. PRL 97, 020801 (2006)

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SLIDE 29

Al+/Hg+ Stability

10 10

1

10

2

10

3

10

4

10

5

10

  • 17

10

  • 16

10

  • 15

10

  • 14

10

  • 13

29096 seconds of data time [seconds]

Δν/ν

7×10-15τ-1/2 Hg vs Maser (AVAR) Hg vs Al (AVAR) Hg vs Al (THEO1)

4 x 10-17

R e c e n t l y : 4 x 1

  • 1

5

τ

  • 1

/ 2

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SLIDE 30

Al+/Hg+ Comparison

Mar Apr May Jun Jul Aug Sep Oct Nov Dec Jan Feb Mar 990.4 990.5 fAl / fHg * 10

15 - 1 052 871 833 148 000

10-16

2006 2007 First comparison of frequency standards at the 17th digit.

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SLIDE 31

27Al+ error budget

Effect Parameter Shift [ x 10 -17] Uncertainty [ x 10 -17] Blackbody shift Operating temperature Micromotion 2nd order Doppler Axial RF field

  • 0.3

0.3 1st-order Doppler from correlated ion movement 1 Radial static field Radial temperature RMS magnetic field I / Isat 0.5 Micromotion 2nd order Doppler

  • 1.2
  • 2
  • 2
  • 68.4
  • 0.7

2nd order Zeeman 0.1 2

  • 74.6

Be+ cooling laser Stark shift Secular 2nd order Doppler 1.5 0.3 Total 2.8

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SLIDE 32

Self-referenced frequency comb

Phase-coherent frequency division

Frequency comb (not to scale!)

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SLIDE 33

Mercury ion Frequency comb NIST-F1 Hydrogen Masers

~

Stable Laser

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SLIDE 34

Effect Correction (Hz)

(at 1.06 PHz)

Fractional uncertainty (10-15) Second-order Zeeman

(B field uncertainty)

1.19 <0.01 quadrupole shift 0.01 Gravitational redshift 0.55 0.01 Micromotion shifts 0.01

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Error budget: Expected fractional systematic uncertainty: ~2 x 10-17

Estimated partial error budget for the near future

  • The immediate future:

Begin averaging over quadrupole shift

Systematic Frequency Shifts

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SLIDE 35

Present and future work

  • Absolute frequency measurements (vs cesium)
  • Aim for fractional uncertainty below 10-15
  • Optical-optical clock comparisons
  • Compare vs Hg+ (second system), Ca, Sr, Yb, Al+
  • Improve understanding of systematics
  • Test of stability of fundamental constants
  • Improvements to reliability & stability:
  • Solid-state laser systems
  • Add laser to quench (de-excite) state

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