A New Era in Optical Atomic Clocks

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1 A New Era in Optical Atomic Clocks Benjamin Bloom, Travis Nicholson, Jason Williams, Sara Campbell, Michael Bishof, Xibo Zhang, Wei Zhang, Sarah Bromley, Ross Hutson, Jun Ye FPUA March 16 th, 2014 Brad Baxley

Experiments in Optical Atomic Clocks The very definition of time 1.

A clear advantage over present standards A new understanding of our planet 1.

Increased accuracy of current gravimeters Image from NOAA Image from MicroG

A better view of what we can already see. 2.

2 Experiments in Optical Atomic Clocks The very definition of time 1. True potential for a redefinition of the SI second 2. A clear advantage over present standards A new understanding of our planet 1. Geodesy / Gravitational mapping 2. Increased accuracy of current gravimeters Image from NOAA Image from MicroG LaCoste Exploration of our universe 1. A better view of what we can already see. 2. Opportunities for mm-wave VLBI A new understanding of our universe 1. Fundamental physics science 2. Variation of fundamental constants 3. Interesting topological phases of matter Figure from Blatt et al, PRL 100, (2008)

3 Introduction to our apparatus Neutral Strontium Two-Level System!

4 Outline Why Optical Lattice Clocks? Trapping and Cooling Strontium Records in Stability o Advances in Clock Laser Technology o Clock Comparisons with High Stability Lowest Published Tot. Uncertainty of any Clock o What were the limitations? o How did we beat them? Summary

Defining Time: A Historical Perspective Technological Advances Depend on Accurate Measurements o Clocks/Calendars based on celestial bodies position Great for planting and harvesting, even proving

hard Galileo Jovian Moons, Edmund Halley Lunar occultations, Nevil Maskelyene Lunar Distance Published tables for everyday of the year Gemma Frisius in the 1500s proposed building chronometers John

5 Defining Time: A Historical Perspective Technological Advances Depend on Accurate Measurements o Clocks/Calendars based on celestial bodies position Great for planting and harvesting, even proving that the earth was round Accuracy and precision poor o AD 325 -> AD 1582, accidentally moved the Vernal Equinox by 10 days Intercontinental Trade Cares about Clocks o o Latitude is easy, Longitude is hard Galileo Jovian Moons, Edmund Halley Lunar occultations, Nevil Maskelyene Lunar Distance Published tables for everyday of the year Gemma Frisius in the 1500s proposed building chronometers John Harrison (six years) Creates chronometer with 10-6 accuracy Note: DISTANCE = TIME (modulo some factors) Fast Forward to Special Relativity and Quantum Mechanics o o o The connections between Distance, Time, and Energy are fundamental Current SI does this with distance, new SI is still up in the air. Cs Beam Clocks Rabi/Ramsey s is periods of oscillation corresponding to Cs HF transition Cs Fountain Clocks Uncertainties down as low as 4.1e-16* *S Weyers et al 2012 Metrologia doi: / /49/1/012 Surpassed by others down as low as 2.1e-16

6 A graduate student s perspective Two Problems 1. Cs Clocks are a mature technology Year Old Technology!

7 What are the Options? Fundamental Noise Due to Projective Quantum Measurement Q = f f σ QPN 1 N Ψ = α g + β e Single-Ion Deep in the Lamb-Dicke regime Figure from Rosenband et al., Science 319 (5871): Figure from Martin Boyd Thesis

8 Outline Why Optical Lattice Clocks? Trapping and Cooling Strontium Records in Stability o Advances in Clock Laser Technology o Clock Comparisons with High Stability Lowest Published Tot. Uncertainty of any Clock o What were the limitations? o How did we beat them? Summary

10 Trapping and Cooling Strontium Oven Effusive oven heated to 575 C Collimated Sr Beam

11 Trapping and Cooling Strontium Sr Sr Hot Oven Zeeman Slower 3D Magneto Optical Trap (MOT)

12 Intercombination Line for Cooling and Nuclear Spin Manipulation 1 S 0-3 P 1 Transition Narrow, 7.4 khz 400 micron

Better Spatial Overlap with red MOT High axial trap frequencies

13 813nm Lattice Trap NEW SYSTEM! Cavity Enhanced Lattice Large Trap Volume for Low Input Power Better Spatial Overlap with red MOT High axial trap frequencies Deep in the Lamb-Dicke regime Red Sideband Blue Sideband 1 S 0 3 P 0 ω trap Clock Laser trap trap recoil

14 Outline Why Optical Lattice Clocks? Trapping and Cooling Strontium Records in Stability o Advances in Clock Laser Technology o Clock Comparisons with High Stability Lowest Published Tot. Uncertainty of any Clock o What were the limitations? o How did we beat them? Summary

15 Allan Variance Frequency Fluctuations calculated over various time bins o Like Moving a Lowpass filter lower and lower in frequency Image from NIST Special Publication 1065 Handbook of Frequency Stability Analysis W.J. Riley

Stability: Clock Lasers 7 cm 40 cm JILA large

Figure from T.L. Nicholson et al, Phys. Rev.

16 Stability: Clock Lasers 7 cm 40 cm JILA large ULE cavity: Swallows et al., IEEE TUFFC 59, 416 (2012). Linewidth: 26 ± 4 mhz Coherence time ~ 20 s Figure from T.L. Nicholson et al, Phys. Rev. Lett. 109, (2012) Q ~ 2 x (698 nm) Bishof et al., PRL 111, (2013).

17 Excitation Fraction Running A Clock g> e> ω trap 1. Pick a Laser Frequency 2. Rabi Flop to the Excited State 3. Measure Ground State 4. Repump Excited State 5. Measure Excited State PID Δ exc ν Sr Detuning (Hz)

Stability: Two Clock Comparison 3 Orders of Magnitude σ Sr = 3. 1 10 16 τ vs σ Cs = 1. 0 10 13 τ Improvement over current standards! σ Sr = 1.

Rosenband, Frequency Comparison of Two High-Accuracy Al + Optical Clocks, Phys. Rev. Lett. 104, 070802 (2010). σ Yb = 3. 2 10 16 τ best single ion clock!

18 Stability: Two Clock Comparison 3 Orders of Magnitude σ Sr = τ vs σ Cs = τ Improvement over current standards! σ Sr = / DAY 1 Order of Magnitude Improvement over the σ Al+ = τ 1. C. W. Chou, D. B. Hume, J. C. J. Koelemeij, D. J. Wineland, T. Rosenband, Frequency Comparison of Two High-Accuracy Al + Optical Clocks, Phys. Rev. Lett. 104, (2010). σ Yb = τ best single ion clock! Figure from T.L. Nicholson et al, Phys. Rev. Lett. 109, (2012) Pushed out to 7 Hours of averaging Time Reported in Hinkley et al., Science 13 September 2013: 341 (6151),

19 Stability Compared to Ion Clocks Gravitational Redshift Measurement o Measured Shift by Height change of 33cm o From C. W. Chou Science 329, 1630 (2010); f f 0 = 4.1 ± Each point is 8000s, total time of data shown = 144,000s Optical Lattice Clock Performance: Two Measurements at the same error bar = 750s of data!

20 Outline Why Optical Lattice Clocks? Trapping and Cooling Strontium Records in Stability o Advances in Clock Laser Technology o Clock Comparisons with High Stability Lowest Reported Tot. Uncertainty of any Clock o What were the limitations? o How did we beat them? Summary

21 Total Uncertainties Lower than Cs Sr Tot. Uncertainty: A.D. Ludlow et al., Sr lattice clock at 1 x fractional uncertainty by remote optical evaluation with a Ca clock., Science 319, (2008). Cs Accuracy: J. Guéna, M. Abgrall, D. Rovera, P. Laurent, B. Chupin, M. Lours, G. Santarelli, P. Rosenbusch, M. E. Tobar, R. Li, K. Gibble, A. Clairon, and S. Bize, IEEE Trans. Ultrasonics, Ferroelectrics, and Freq. Control, 59, 391 (2012). Al + Tot. Uncertainty: C. W. Chou, D. B. Hume, J. C. J. Koelemeij, D. J. Wineland, T. Rosenband, Frequency Comparison of Two High-Accuracy Al + Optical Clocks, Phys. Rev. Lett. 104, (2010). Campbell et al., Metrologia 45, 539 (2008)

22 Multiple Paths o o o o Atomic Trapping Effects Measuring Really well Problem 1: Density Shift Solved! 2D Lattice Suppresses Density Shift (JILA, Sr) Drain Loading / Low Density Sample (SYRTE) Ramsey Density Shift Zero Crossing (NIST, Yb) Implemented Cavity Lattice Lower Density Sample of atoms Large Atom Number Due to better overlap with MOT Modulate Density Measure Shift per Atom Shift measured for 2000 atoms ± Made Even lower by working with low lattice depths Figure from T.L. Nicholson et al, Phys. Rev. Lett. 109, (2012)

23 Problem 2: Lattice Stark Shifts Exhaustive study performed by LNS-SYRTE See P.G. Westergaard et al., Phys. Rev. Lett. 106, (2011) o Atomic Trapping Effects Whereas our system was designed with Density Shift in mind, theirs was designed with Lattice Stark measurements in mind. From Bloom et al., Nature, 2014

24 Two surprises along the way DC Stark ν up α E background + E applied 2 ν down α E background E applied 2 ***New Results*** Demonstrated 1D electric field servo at in 15 minutes of clock operation. In three axes From Bloom et al., Nature, 2014

25 Two surprises along the way Magnetic Field Wander Unpolarized Line Nuclear Spin States 3 P 0 1 S 0 Active control! The world s most expensive magnetometer! 3 coil pairs From Bloom et al., Nature, 2014

, PRL 109, 263004 (2012) ν BBR = ν stat T 4 + ν dyn T 6 If you are going to measure temperature, you

26 Blackbody Radiation Shifts 1. Effective DC field from BBR spectrum (Static) 2. Atoms see photons that stark shift them (Dynamic) From 2009 Temperature? From Middelmann, et al., PRL 109, (2012) ν BBR = ν stat T 4 + ν dyn T 6 If you are going to measure temperature, you might as well just use a thermometer From Safronova, et al., IEEE Blackbody Radiation Shifts and Theoretical Contributions to Atomic Clock Research

27 Blackbody Radiation Shifts 16 mk Accuracy at 300 K

What kind of BBR do the Atoms see? Created a Ray Tracing Program to do just that! Temperature Enclosure From Chandos and Chandos, Applied Optics, Vol. 13, Issue 9, pp.

28 What kind of BBR do the Atoms see? Created a Ray Tracing Program to do just that! Temperature Enclosure From Chandos and Chandos, Applied Optics, Vol. 13, Issue 9, pp (1974) BBR spectrum is an emissivity/solid Angle weighted average From Bloom et al., Nature, 2014 At exact center of chamber Name of Object Effective solid angle (Rounded to 0.1 %) Top Viewport 37.4 % Bottom Viewport 37.4 % Metal Chamber 0.3 % 2 ¾ CF 17.9 % 1 1/3 CF 6.7 % ZS Window 0.5%

29 Put It Together Shifts and Uncertainties in Fractional Frequency Units Sources for Shift SrI SrI SrII SrII BBR Static BBR Dynamic Density Shift Lattice Stark Probe Beam AC Stark st Order Zeeman 0 < nd Order Zeeman Residual Lattice Vector Shift 0 <0.2 <0.1 0 <0.2 <0.1 Second lowest published lattice clock to date! Line Pulling & Tunneling 0 <0.1 0 <0.1 DC Stark Background Gas Collisions AOM Phase Chirp nd Order Doppler 0 <0.1 0 <0.1 Servo Error Totals Lowest published frequency uncertainty to date! From Bloom et al., Nature, 2014

30 Where once we had Oscillators, Now, we have Clocks! From Bloom et al., Nature, 2014

31 Stacking up to the competition Sr: Lowest published uncertainty of all atomic clocks: 6.4 x Reaching this level 100x faster than ion clocks

32 Future Work 3 D State Lifetime 2 nd Systematic Evaluation New Apparatus!

33 3 D State Lifetime Introductory differential equations! OPO stabilized to Cavity Found 3 3 D 1 Lines Detected 689nm photons Phys. Rev. A, 86(5) (2012)

34 New system for quantum gas CAD experiments Design goals: Long vacuum lifetime (> 60 s) Single-pancake spectroscopic resolution Optical access, flexibility Dipolar physics JILA KRb Experiment Real life! Artificial gauge fields Precision Measurement Quantum Physics

35 New Sr System 2D MOT Main Chamber 1. No line of sight to hot windows/oven 2. TiZrV coated Ti-Sub Pump Oven Zeeman Slower 10-9 vacuum Bucket Windows GOAL: Vacuum Lifetimes > 60s Large Conductance Low Magnetic field 300 L/s NEG + Ion pump

36 Sr optical clock - New Records in stability & accuracy Jun Ye ALUMNI M. Martin (Caltech) J. Williams (JPL) M. Swallows (AO Sense) S. Blatt (Harvard) A. Ludlow (NIST) Y. Lin (NIM, Beijing) G. Campbell (JQI, NIST) M. Boyd (AO Sense) J. Thomsen (U. Copenhagen) T. Zelevinsky (Columbia U.) T. Zanon (Univ. Paris 13) S. Foreman (U. San Fran) X. Huang (WIPM) T. Ido (Tokyo NICT) T. Loftus (AO Sense) X. Xu (ECNU) Jun Ye Sr II B. Bloom T. Nicholson S. Campbell R. Hutson SrI M. Bishof X. Zhang S. Bromley W. Zhang A. Gorshkov, M. Holland, M. Lukin, P. Zoller, A.M. Rey

37 Travis Nicholson Sara Campbell Bryce Bjork Bryce Gadway Craig Benko Michael Bishof Xibo Zhang Jun Ye Sarah Bromley Ben Bloom Dan Gresh Mark Yeo John Hall Kevin Cossel David Reens Wei Zhang Matt Hummond Jacob Covey Hao Wu Steven Moses Alejandra Collopy Linqing Hua Ross Hutson Bryan Changala

38 EXTRA SLIDES

Kessler, et al., Nature Photonics, 6, 10 (2012).

39 The next generation of stable lasers Challenge 1: Noise from spacer, substrates In collaboration with PTB T. Kessler, et al., Nature Photonics, 6, 10 (2012). Use single-crystal silicon to make both spacer and substrate: Wei Zhang

40 The next generation of stable lasers Challenge 2: Noise from mirror coatings In collaboration with Garrett Cole, Aspelmeyer group, U. of Vienna G. D. Cole, et al., Nature Photonics, 7, 8 (2013). Wei Zhang GaAs/AlGaAs DBR disc 6 cm cavity cooled to 17 K (Si zero crossing) stability at 1 second < 10 mhz linewidth

41 quotes No wonder you're late. Why, this watch is exactly two days slow. Mad Hatter (Lewis Carroll) Time flies like an arrow. Fruit flies like a banana. Groucho Marx A committee is a group that keeps minutes and loses hours. Milton Berle The future has already arrived. It s just not evenly distributed yet. William Gibson How did it get so late so soon? It's night before it's afternoon. December is here before its June. My goodness how the time has flewn. How did it get so late so soon? - Dr. Seuss We have so much time, and so little to do! Strike that, reverse it. - Willy Wonka, Willy Wonka and the Chocolate Factory The only reason for time is so that everything doesn't happen at once. - Albert Einstein Time is what prevents everything from happening at once. ~John Archibald Wheeler With time and patience the mulberry leaf becomes a silk gown. - Chinese proverb Time is an illusion, lunchtime doubly so. - Douglas Adams Time is not a line, but a series of now points. - Taisen Deshimaru Time is the longest distance between two places. - Tennessee Williams Clocks slay time... time is dead as long as it is being clicked off by little wheels; only when the clock stops does time come to life. ~William Faulkner Time is the fire in which we burn. ~Delmore Schwartz, "Calmly We Walk Through This April's Day," 1937 Tomorrow, and tomorrow, and tomorrow, Creeps in this petty pace from day to day ~William Shakespeare How long a minute is, depends on which side of the bathroom door you're on. ~Zall's Second Law Time is but the stream I go a-fishing in. ~Henry David Thoreau The Present is a Point just passed. ~David Russell Time has no divisions to mark its passage, there is never a thunderstorm or blare of trumpets to announce the beginning of a new month or year. Even when a new century begins it is only we mortals who ring bells and fire off pistols. THOMAS MANN, The Magic Mountain Always in motion is the future. YODA, Star Wars Episode V: The Empire Strikes Back Time is a measure of space, just as a range-finder is a measure of space, but measuring locks us into the place we measure. FRANK HERBERT, Children of Dune Disorder increases with time because we measure time in the direction in which disorder increases. STEPHEN HAWKING, A Brief History of Time Time can also be a place... Everything depends on where you are standing, on where you look or what you hear. The measure of it is found in consciousness itself. FRANK HERBERT, God Emperor of Dune The fluid cradle of events (time). WILLIAM FAULKNER, Absalom, Absalom! Never measure anything but frequency! was the advice [1] of the late Arthur Schawlow Optical frequency standards based on a large number of neutral Sr atoms are envisaged to lead to similarly low uncertainties [9], which means that one can now reproduce optical frequencies that are much more precise than they are accurate. Fritz Riehle in regards to our paper

laser (Iodine stabilized HeNe laser option available for

42 Gravimeters Notes on Current Gravimeters o o 1 MHz frequency error -> 2 microgal accuracy Notes: Frequency stabilized HeNe laser (Iodine stabilized HeNe laser option available for highest accuracy applications). Rubidium atomic clock From MicroG Lacoste

43 Synchronous Clock

44 Magneto-Optical Trap Image from Martin Boyd s PhD Thesis

45 Why Neutral Sr? Convenient State Mixing o Spin Orbit Coupling leads to narrow intercombination line transition Normally S = 1 is forbidden o Hyperfine Interaction creates extremely narrow clock transition Normally S = 1 is forbidden and J = 0 J = 0 is also forbidden Image from M.M. Boyd, et al., Nuclear spin effects in optical lattice clocks, PRA, 76 (2007)

46 Next Generation Clock Lasers 22 cm PTB JILA: Silicon crystal cavity Kessler et al., Nature Photonics 6, 687 (2012) feasible (Vienna JILA) Cole et al., Nature Photonics 7, 644 (2013).

47 New Frontiers in Optical Metrology Benjamin Bloom Ye Labs Intel Hillsboro, OR Dec 13 th, 2013

Stability: Synchronous Interrogation Sr I

48 Stability: Synchronous Interrogation Sr I Sr II JILA Sr I AOM1 Local oscillator AOM2 Good for Diagnostics and Systematic Evaluations JILA Sr II Work similar to: Takamoto et al., Nature Photonics 5, 288 (2011) 87 Sr - 88 Sr comparisons Bize et al., IEEE Trans. Ultrason. Ferroelectr. Freq. Control 47, 1253 (2000) Cs Rb fountain clock comparisons

49 Dipolar physics in Sr D. E. Chang et al., PRA 69, (2004 ). Strongly-affected by lattice geometry and peaked in lattice configurations where interactions between atoms add constructively 2.5e-17 shift for unity-filled lattice, resonant geometry (~40 times more dense than now)

6 μm 3 P 0 3 D 1 The 3D1 lifetime has been measured to 7% uncertainty, calculated to 1% uncertainty.

50 Accuracy: 3 D 1 lifetime measurement Recall: Δν BBR = Δν static T 6 + Δν dynamic T 6 Half of our total uncertainty is due to 1% uncertainty in Δν dynamic 2.6 μm 3 P 0 3 D 1 The 3D1 lifetime has been measured to 7% uncertainty, calculated to 1% uncertainty. If it goes down by a factor of 2 to 0.5%, the uncertainty in the coefficient itself goes down by a factor of 2. Next biggest uncertainty (of 0.1%) is in the branching ratio of the decay from 3D1 into the 3P manifold.

Spin Many-Body Physics Matthew Swallows, Drive vs. interaction energy Drive vs.

probe interaction spin many-body energy et#al physics 331 already with clock Benko precision al Long 324 coherence time et#al allows

U" U" Interaction*energy* Interaction*energy* Interaction*energy* Tune Rabi frequency >>*U: *Mean=fie l d* shift* *Mean=fie l d*

51 Spin Many-Body Physics Matthew Swallows, Drive vs. interaction energy Drive vs. interaction energy Michael Martin, Michael Bishof, 324 et#al 331 Xibo Zhang, Craig Drive Can 324 vs. probe interaction spin many-body energy et#al physics 331 already with clock Benko precision al Long 324 coherence time et#al allows 331 small Rabi frequencies Theory: Javier von- Stecher, Alexei Gorshkov, Ana Maria Rey ẑ ŷ xˆ Rabi*frequency* W Rabi*frequency* U" U" U" Interaction*energy* Interaction*energy* Interaction*energy* Tune Rabi frequency >>*U: *Mean=fie l d* shift* *Mean=fie l d* shift* W >>*U: *Mean=fie l d* shift* Tune interactions g e e e g g <*U: *Correlated*spin*spectrum* W <*U: *Correlated*spin*spectrum* <*U: *Correlated*spin*spectrum* e g e e g g M. J. Martin et al., Science 341, 632 (2013)

52 Spin Many-Body Physics

Quantum Metrology Optical Atomic Clocks & Many-Body Physics

Quantum Metrology Optical Atomic Clocks & Many-Body Physics Jun Ye JILA, National Institute of Standards & Technology and University of Colorado APS 4CS Fall 2011 meeting, Tucson, Oct. 22, 2011 Many-body