Precision measurement with ultracold atoms & molecules Jun Ye - - PowerPoint PPT Presentation

Precision measurement with ultracold atoms & molecules

Jun Ye JILA, National Institute of Standards and Technology and Department of Physics, University of Colorado at Boulder

$ Funding $ NIST, ONR, NSF, AFOSR, NASA, DOE

http://jilawww.colorado.edu/YeLabs

Advances in Precision tests and Experimental Gravitation in Space Firenze, September 28, 2006

First, let there be light

Continuous wave laser:

< 1 Hz stability and accuracy

Ultrafast pulse:

< 1 fs generation and control Figure of merit: 10-15 Phase coherence after 1015 optical cycles

Precision spectroscopy and quantum control at highest resolution over widest optical bandwidth

Frequency comb: state-of-the-art

νn= n fr – fo

• Optical Synthesizer

I(ν) ν

fr f0

Visible

Frequency (Hz)

1010 1011 1012 1013 1014 1015

• Freq. comb

106 :1 Reduction Gear

Molecular spectroscopy

Thorpe et al., Science 311, 1595 (2006).

• C. Gohle et al.,

Nature 436, 234 (2005). Jones et al. PRL 94, 193201 (2005).

XUV comb

Stowe et al., PRL 96, 153001(2006).

Quantum control

Optical coherence > 1 s, across entire visible

Laser 2 1064 nm Cavity 2 Laser 1 700 nm Cavity 1

ν Laser 1 Laser 2

Femto comb 30 m noise-cancelled fiber 35 m noise-cancelled fiber

Ludlow et al., PRL 96, 033003(2006).

• 6
• 4
• 2

2 4 6 8 10 1 2 3

Linear Signal (a. u.) Optical linewidth: 250 mHz

4/11/ 2006 Hz

Oscillator Counter ∆ν

νa Atoms

New era for optical atomic clocks

Diddams et al., Science 293, 825 (2001). Ye et al, Phys. Rev. Lett. 87, 270801 (2001).

Feedback (accuracy) Ultrastable laser

• ptical comb
• ptical frequency

synthesizer & counter RF or optical readout

Accurate atomic clocks

• ptical

Single Hg+

Sr Cs fountain: SYRTE, NIST, PTB, …

Yb+, Sr+, Al+ …

All in one – Space Clock and Laser Ranging

Time meets length

Space based interferometer

Courtesy of P. Bender

Ye, Opt. Lett. 29, 1153 (2004).

+ Inertial Sensor

• Prof. G. Tino

PRL 2006

Clean separation between internal & external degrees of freedom Control of matter

• Learning from ion trappers

Long - term quantum coherence: Both in well defined quantum states

Magic wavelength dipole trap

Trapping of Single Atoms in Cavity QED

Ye, Vernooy & Kimble, Phys. Rev. Lett. 83, 4987 (1999).

For clocks: Katori et al., Katori et al., J. Phys. Soc. Jpn 68, 2429 (1999) 6th Symp. Freq. Standards & Metrology (2002);

• Phys. Rev. Lett. 91, 173005 (2003).

T ~ 0.5 photon recoil ~ 220 nK

Cool Alkaline Earth – Strontium

1S0 3P1 1P1

689 nm (7.4 kHz) 461nm (32 MHz)

3P0

698 nm

∆ν ∼1 mHz

~ 1 mHz ~10-18

87Sr 1S0-3P0

δν/ν0 at 1s ∆ν

τ ν δν 1 1 1 ⋅ ⋅ ≈ N S Q

noise

ν ∆ ν0 ≈ Q

JILA work: Phys.Rev.Lett. 90, 193002 (2003); Phys.Rev.Lett. 93, 073003 (2004); Phys.Rev.Lett. 94, 153001 (2005); Phys.Rev.Lett. 94, 173002 (2005); Phys.Rev.Lett. 96, 033003 (2006); Phys.Rev.Lett. 96, 203201 (2006).

Spectroscopy at the magic wavelength

trap

ω h

1S0 3P0

trap clock trap recoil

ω ω ω << Γ <<

1-D Lamb-Dicke Regime η = kx0 = (ωrecoil / ωz )0.5 ~ 0.23

• 60
• 40
• 20

20 40 60 500 1000 1500 2000 2500 3000 3500

Photon counts Optical frequency (Hz)

Red sideband

ωtrap

Blue SB Carrier

• 20
• 10

10 20 30

1200 1400 1600 1800 2000 2200 2400 2600 2800 3000 3200

Photon Counts Clock Laser Detuning (Hz) FWHM: 4.6 Hz

April, 2006

Q ~ 1 x 1014

Single trace without averaging

Zoom into the carrier of 87Sr 1S0 – 3P0

E

g

Reproducibility ~ 6 x 10-16 (March – September, 2006) Projected stability < 1 x 10-15 at 1 s

• 3P0 g-factor different than 1S0 due to HFI
• Shift of ~110 x mF Hz/Gauss for ∆mF=0
• State preparation, field control
• HF structure introduces slight lattice polarization sensitivity

Differential g-factor – Tensor polarizability

1S0 3P0

HFI

1P1 3P1

I = 9/2

mf

• 9/2

+9/2

1S0 3P0

mf

• 9/2

+9/2

1S0 3P0 Proposals based on Bosons: Santra et al., PRL 94, 173002 (2005). Hong et al., PRL 94, 050801 (2005). Barber et al., PRL 96, 083002 (2006).

• 400
• 200

200 400 0.00 0.02 0.04 0.06 0.08 0.10

• 9/2
• 7/2
• 5/2
• 3/2
• 1/2

+1/2 +3/2 +9/2 +7/2

3P0 Signal (Norm.)

L aser D etuning (H z)

+5/2

Optical Measurement of Nuclear g-factor

(NMR-like experiment in the optical domain) π

2 1 + 2 9 + 2 3 + 2 5 + 2 7 + 2 1 + 2 9 + 2 3 + 2 5 + 2 7 + 2 1 − 2 7 − 2 9 − 2 5 − 2 3 − 2 1 − 2 7 − 2 9 − 2 5 − 2 3 −

1S 3P

No net electronic angular momentum ∆g = -108.5(4) Hz/(G mF)

3P0 lifetime 140(40) s

1S0 3P0

1 2 3 4 5 6 2 4 6 8

Occurrences Transition Linewidth (Hz) Fourier Limit

~1.8 Hz

• 6
• 4
• 2

2 4 6 0.00 0.02 0.04 0.06 0.08 0.10

3P0(mF=5/2) Population

Laser Detuning (Hz)

1.5 Hz

• 6
• 4
• 2

2 4 6 0.00 0.02 0.04 0.06 0.08 0.10

3P0(mF=5/2) Population

Laser Detuning (Hz)

2.1 Hz

Coherent spectroscopy Q ~ 3 x 1014

• 60
• 30

30 60 90 120 0.00 0.04 0.08 0.12 0.16 0.20

3P0(mF=5/2) Population

Laser Detuning (Hz)

• 10 -5

5 10 0.00 0.04 0.08

10 Hz 1.7 Hz

Ramsey

Total uncertainty 0.29 Hz 6.7 x 10-16

Understanding systematics: Collision shift and Lattice AC Stark shift

• 20
• 15
• 10
• 5

5 10 15 20 10 20 30 40 50 60

Occurances Density Shift (Hz/(10

11cm

• 3))

Density shift 0 (0.14) Hz

• 40
• 30
• 20
• 10

10 20 30 40 20 40 60 80 100 120

Occurances Lattice Shift (Hz/I0)

Lattice Stark shift

• 0.108(0.257) Hz

Zeeman shift, 0.10 Hz, 2.3 E-16 Lattice AC Stark, 0.26 Hz, 6.0 E-16 Atom density shift, 0.14 Hz, 3.3 E-16 Probe AC Stark, 0.05 Hz, 1.0 E-16 Blackbody 0.03 Hz 0.7 E-16 Systematic Total 0.39 Hz 7.3 E-16

Systematic uncertainty evaluations

For Absolute frequency measurement against Cs: Gravitational shift 3.0 E-16 Counting statistics 6.0 E-16 NIST Maser calibration 2.0 E-15 Measurement uncertainty Total 2.2 E-15

840 860 880 900 920 940 960

JILA May 2006 (preliminary)

Measurements Frequency- 429,228,004,229,000 Hz

Tokyo 2005 (A) JILA 2005 (B) Paris 2006 (C) Tokyo 2006 (D)

(A)Takamoto et al., Nature 435, 321 (2005). (B)Ludlow et al., Phys. Rev. Lett. 96, 033003 (2006). (C)Le Targat et al., arXiv:physics/0605200 (D) ICAP proceedings, Innsbruck, July 2006. (E)Takamoto et al., arXiv:physics/0608212

Agreement among Boulder, Paris, and Tokyo

(D) (E)

Ultracold molecules: Test fundamental principles

QED

Electronic ~ α

e- e- e- e-

• Ultrahigh resolution spectroscopy
• Standards in wide spectral ranges
• Molecular interferometry
• Precision measurement

Excited electronic state Ground electronic state

One system, two different fundamental forces!

Vibration ~ me/mp

(mass on a spring) Strong interactions

Ultracold Sr2 Molecules in Lattice

Narrow lines – Favorable decay to electronic ground state Structureless ground state – Small branching ratio losses Sr + Sr Sr + Sr*

Photo association

Raman transition for ground state production

Molecular Clock – Sensitivity to Mass Ratio

mp ↑

Molecular potentials depend on electron mass, me Kinetic energy depends on proton mass, mp Vibrational spacings depend on mp / me Precision tests of time variation of mp / me?

me mp mp

• D. DeMille, private communications (2005).

Chin and Flambaum, PRL 96, 230801 (2006).

• S. Schiller, molecular ions

Mass ratio tests

Vg

Sr2 νpump νprobe

δ(νpump – νprobe) < 0.5 Hz

ν

0u

Homonuclear molecules are best Relative Raman frequency measurement 0.3 Hz (fs comb), potential depth 3 x 1013 Hz → 1 x 10-14 Atomic clocks: 6 x 10-15 / year, but model-dependent, mainly QED effects

Test of fundamental constants

• Early universe
• Not so clear…

Webb et al., PRL 87, 091301 (2001).

• Astron. Astrophys. 415, L7 (2004).

– Conflicting results

α: fine structure constant

• Modern epoch
• Atomic clock measurements

are consistent with zero ∆α/α < 10-15/yr ν

Cold OH molecules to constrain α

Hyperfine interactions ~ α 4 Lambda doubling ~ α 0.4

2Π3/2

F’= 2 F’= 1 F= 2 F= 1

Multiple transitions from the same gas cloud (different dependences on α) (Self check on systematics) Current uncertainly in laboratory based experiments is 100 Hz, leading to ∆α/α ~ 10-5

ter Meulen & Dymanus, Astrophys. J. 172, L21(1972).

OH megamasers High redshift z > 1

Darling, Phys. Rev. Lett 91, 011301 (2003). Chengalur et al., Phys. Rev. Lett. 91, 241302 (2003). Kanekar et al., Phys. Rev. Lett. 93, 051302 (2004).

+

• +
• p

Fnet v

Stark deceleration

Direct manipulation of ground state molecules

+

• p

v Energy Position

Initial cooling important (supersonic jets: single internal quantum state; external

• temp. ~ 1 K in a moving frame)

Phase space selection (~ 10 mK) Applicable to a large variety

• f polar molecules

Bethlem, Berden, Meijer,

• Phys. Rev. Lett. 83 1558 (1999).

Electrode Electrode

Stark Decelerator

Slower electrodes Stark energy Position

Cold OH molecules

1.4 1.6 1.8 2.0 2.2 2.4 2.6 2.8 0.00 0.25 0.50 0.75 1.00

OH density (arb.) Time (ms)

370 m/s 336 m/s 300 m/s 259 m/s 211 m/s 148 m/s 33 m/s

Bochinski et al., Phys. Rev. Lett. 91, 243001 (2003). Bochinski et al, Phys. Rev. A 70, 043410 (2004).

Cold molecular beams: 550 m/s to rest Temp: 1 K to 10 mK 104 – 106 molecules 105 – 107 /cm3 density

Magnetic trapping of OH

d e c e l e r a t

• r

Electric quadrupole Magnetic trap coil Imaging & future cavity cooling

Electrodes can be used as quadrupole lens to apply uniform E field

Magnetic trapping of OH

Magnetic trapping of OH

4 6 8 10 50 100 150 200

Signal - Background (4800 Records) Time from Discharge [ms]

Theory Data

• Sep. 6, 2006

Precision measurement of OH ground structure

• SUM (2 satellites)

= SUM (2 main lines)

• Satellites calibrate B
• Observed satellites

conjugate

Measurement accuracy for all four lines: 4 – 10 Hz (x10 improvement)

2Π3/2

F’= 2 F’= 1 F= 2 F= 1 ∆F = 0 ∆F = ±1

Hudson et al., Phys. Rev. Lett. 96, 143004 (2006). Kanekar et al., PRL 93, 051302 (2004). Lev et al., arXiv:physics/0608194, August 2006.

What about space?

Possible sources of error:

• EM fields in space
• Varying Doppler effects

for different lines Solutions: Main lines versus satellite lines Emission and conjugate absorption OH sum rule Astrophysical measurements coming under 100 Hz accuracy. Deep surveys of OH megamasers are active from the local Universe to red shift z ~ 4. Tests on ∆α / α and ∆β / β (β = me/mp) at 1 ppm over 1010 yr.

Special thanks

Femtosecond comb & Quantum control

• S. Foreman
• M. Thorpe
• D. Hudson
• M. Stowe
• Dr. A. Pe’er
• Dr. R. J. Jones (Arizona)
• Dr. K. Moll (Precision Ph)

Ultracold Sr & Sr2

• M. Boyd
• A. Ludlow
• S. Blatt
• Dr. T. Zelevinsky
• Dr. T. Zanon
• Dr. T. Ido (Tokyo)

Cold Polar Molecules

• B. Sawyer
• B. Stuhl
• Dr. B. Lev
• E. Hudson (Yale)

http://jilawww.colorado.edu/YeLabs Collaborators

• J. Bohn, S. Cundiff, J. Hall, C. Greene (JILA)
• P. Julienne, S. Diddams, J. Bergquist, L. Hollberg, T. Parker (NIST)
• E. Eyler (UConn), F. Krausz (MPQ)