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光格子時計と光周波数コムによる量子標準の開発
Development of Quantum Standard Using Optical Lattice Clocks and
Combs洪 鋒雷、安田正美、 赤松大輔、稲場 肇、保坂一元
Feng-Lei Hong, Masami Yasuda, Daisuke Akamatsu, Hajime Inaba, and Kazumoto Hosaka
産業技術総合研究所National Institute of Advanced Industrial Science and Technology (AIST)
量子情報処理プロジェクト全体会議2011京都国際ホテル 12月9日
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Contents
• “Redefinition of the second”
• Yb optical lattice clock
• Sr/Yb dual optical lattice clock
• Narrow linewidth lasers and optical frequency combs
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Contents
• “Redefinition of the second”
• Yb optical lattice clock
• Sr/Yb dual optical lattice clock
• Narrow linewidth lasers and optical frequency combs
![Page 4: Development of Quantum Standard Using Optical Lattice ......Using Optical Lattice Clocks and Combs 洪鋒雷、安田正美、赤松大輔、稲場肇、保坂一元 Feng-Lei Hong,](https://reader036.vdocuments.pub/reader036/viewer/2022071404/60f7f5470b9bfd01f765d163/html5/thumbnails/4.jpg)
CIPM recommended laser frequencies
1×10-14429228066418012 Hz88Sr, 5s2 1S0 - 5s5p 3P0 transition698 nm
1×10-15429228004229873.7 Hz87Sr, 5s2 1S0 - 5s5p 3P0 transition698 nm
4×10-14411042129776393 Hz40Ca+, 4s 2S1/2 – 3d 2D5/2 transition729 nm
1.6×10-13518295836590864 Hz171Yb, 6s2 1S0 (F=1/2) - 6s6p 3P0 (F=1/2) transition578 nm
4.5×10-11551580162400 kHzHe-Ne laser, 127I2, R(106)28-8:b10543 nm
3×10-1288376181600.18 kHzHe-Ne laser, CH4, n3, P(7), F2(2)3.39mm
2.6×10-11194369569384 kHz13C2H2, P(16)(ν1 + ν3) transition1.5mm
1.3×10-11385285142375 kHz85Rb, 5S1/2(F=3) - 5D5/2(F=5), 2 photon transition778 nm
7×10-15444779044095484 Hz88Sr+, 52S1/2 - 42D5/2674 nm
1.8×10-14455986240494140 Hz40Ca, 1S0 - 3P1, ΔmJ = 0657 nm
2.1×10-11473612353604 kHzHe-Ne laser, 127I2, R(127)11-5:a16633 nm
8.9×10-12563260223513 kHzNd:YAG laser, 127I2, R(56)32-0:a10532 nm
6×10-14642121496772657 Hz171Yb+, 2S1/2 (F=0) - 2F7/2 (F=3) transition467 nm
9×10-15688358979309308 Hz171Yb+, 6s2S1/2 (F=0) - 5d2D3/2 (F=2) transition436 nm
3×10-151064721609899145 Hz199Hg+, 5d106s 2S1/2 (F=0) - 5d96s2 2D5/2 (F=2) transition282 nm
2.0×10-131233030706593.55 kHz1H, 1S - 2S, 2 photon transition243 nm
3.6×10-131267402452899.92 kHz115In+, 5s2 1S0 - 5s5p 3P0 transition237 nm
UncertaintyFrequencyLaser and referenceWavelenght
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Contents
• “Redefinition of the second”
• Yb optical lattice clock
• Sr/Yb dual optical lattice clock
• Narrow linewidth lasers and optical frequency combs
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BackgroundBackgroundWe have demonstrated 171Yb optical lattice clock in 2009.
EffectCorrection
(Hz)Uncertainty
(Hz)Blackbody radiation shift
+ 1.32 0.13
Gravitational shift - 1.19 0.032nd order Zeeman shift + 0.4 0.05Scalar light shift 0 14Clock laser light shift - 0.04 < 0.01Paper lock error 0 23UTC (NMIJ) 0 5Total + 0.49 27
cf. NIST group’s GREAT result: N. D. Lemke et al., “Spin-1/2 Optical Lattice Clock”Phys. Rev. Lett., vol. 103, pp. 063001, August 2009f = 518 295 836 590 865.2(0.7) Hz (Fractional uncertainty 1.4 x 10-15)
CIPM Recommended frequency list (June, 2009)
1S0(F = 1/2)-3P0(F = 1/2) transition in 171Ybf = 518 295 836 590 864 (28) Hz(Fractional uncertainty 5.4×10-14)
To reduce the uncertainty,we have to lock the clock laser to the clock transition.
We improve the spectroscopy signal by normalizing the atom number.
Yb OLC can be so good!
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399 nm
01100
Blue MOT Green MOT
556 nm
759 nm
Probe
90 10 1850
Phase
Time (ms)
578nm
Clock
100 5
Laser
20 5
Timing chart of the spectroscopy w/ atom # normalization
578nm(deexcitation pulse)
(excitation pulse)
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Locking to the atomic transition
ULE cavity drift ~ 200mHz/sULE cavity drift rate ~ 240 mHz/s
Measured with H-maser 2 years ago
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Future Prospects• Lock the clock laser to the center of σ (π) transitions• Next absolute frequency measurement in a few month.
(the result will be limited by our Cs clock.) 171Yb clock uncertainty x10-16 How to tackle?BBR 2.5 Cooling the environmentLattice polarizability 2.0 Well-define the lattice laser.
(Freq., Power. Pol.)Density 0.8 Further cooling atoms
-> Collision suppression Hyperpolarizability 0.7 Further cooling atoms
-> Less lattice laser power
(excerpt from “Spin-1/2 Optical Lattice Clock”, PRL 103, 063001 (2009))
Sr optical lattice clock project has been started.→ opt.-opt. comparison beyond our Cs-limit
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Contents
• “Redefinition of the second”
• Yb optical lattice clock
• Sr/Yb dual optical lattice clock
• Narrow linewidth lasers and optical frequency combs
![Page 11: Development of Quantum Standard Using Optical Lattice ......Using Optical Lattice Clocks and Combs 洪鋒雷、安田正美、赤松大輔、稲場肇、保坂一元 Feng-Lei Hong,](https://reader036.vdocuments.pub/reader036/viewer/2022071404/60f7f5470b9bfd01f765d163/html5/thumbnails/11.jpg)
Dual Optical Lattice ClockDual Optical Lattice Clock
Yb OLC and Sr OLC in a same chamber1) Contribution to the Sr lattice clock community; 2) As a second optical clock to be used for the evaluation of the Yb lattice clock; 3) Measurement of the Sr/Yb frequency ratio with an uncertainty beyond the Cs limit;4) Contribution to the experimental demonstration of alpha variation;5) Demonstration an atomic clock with suppressed BBR shift.
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A diode laser for intercombination coolingA diode laser for intercombination cooling
Y. Li et al., Appl. Phys. B 78, 315
a heat pipe and a high finesse cavity are conventionally used for narrowing the linewidth.
The frequency of the cooling laser has to be locked to a frequency reference.
The linewidth has to be sub-kHz to cool the atoms down to μK level.
We employ “a linewidth transfer method” with optical freq. comb.We employ “a linewidth transfer method” with optical freq. comb.
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Slow servo
Fast servo
Current control
waveguide
EOM
EDFA
EDFA
HNLF f - 2f
for clock laser
HNLF
TEC
LD
fceo locking electronics
EDFA
fbeat locking electronics
fbeat
CEO port
HNLFNarrow linewidth
Nd:YAG laser f=1064 nm
Linewidth transfer for Strontium OLC
EDFA HNLFunder construction
for 2nd stage cooling laser
Δf~20Hz
ULE cavity(F~735,000)Y. Nakajima et al., Opt. Express 19, 2046 (2010).
K. Hosaka et al., IEEE Trans. Ultra. Ferro. Freq. Cont., 57, 606 (2010).
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3P1
2nd CoolingTransition
689nm
Repump
1D2
3S1
Repump679nm 707nm
3P2
1P1
Optical Dipole Trapping of Sr at a magic wavelength
1st Cooling461nm
1S0
optical lattice813 nm
3P0
optical lattice813 nm
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Optical Dipole Trap of Optical Dipole Trap of 8888SrSr
g
813.4nm (magic wavelength)120mW
100um
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Contents
• “Redefinition of the second”
• Yb optical lattice clock
• Sr/Yb dual optical lattice clock
• Narrow linewidth lasers and optical frequency combs
![Page 17: Development of Quantum Standard Using Optical Lattice ......Using Optical Lattice Clocks and Combs 洪鋒雷、安田正美、赤松大輔、稲場肇、保坂一元 Feng-Lei Hong,](https://reader036.vdocuments.pub/reader036/viewer/2022071404/60f7f5470b9bfd01f765d163/html5/thumbnails/17.jpg)
578 nm & 1064 nm578 nm & 1064 nm reference cavitiesreference cavities• Ultra-low expansivity glass (ULE) etalon• Length : 75 mm• Finesse : ~400,000 (+/- 150,000)• The cavity was bonded to an Al disc using silicon RTV• Turning point of thermal expansivity is around room temp• Two-layer temperature control (± 1 mK)• Vacuum : ~10-5 Pa
ULE cavity
75 mm
Teflon post
Al disc
Al vacuum flange
Ion pump (2l/sec)
Heater on vacuum chamber (1st layer)
Heater on Cu box (2nd layer)
578nm
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②Continuous wave lasers are phase locked to
the comb.
Applications to optical lattice clocks using narrow linewidth combs
Frequency combNd:YAG
PDH lock
Δν~1 Hz
ν ν
Yb lattice clockClock laser (578 nm)
Sr lattice clock2nd cooling laser (689 nm)
Ultra stable laser at 1064 nm
High-finesse optical cavity at 1064 nm
The comb transfers the linewidth to other lasers
at some wavelengths.
①Comb is phase locked to the ultra-stable laser
at 1064 nm.
Sr lattice clockClock laser (698 nm)
OK!OK!
OK!OK!
SoonSoon
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Fiber combs are not only very reliable for long-term operation but also useful to transfer linewidth and frequency stability from one wavelength to another.
Linewidth transfer using narrow linewidth combs
Relative linewidth < 30 mHz
30.5 mHz(Resolution limit)
The energy concentration to the coherent carrier is 99 %
Enlarge
Out-of-loop beat signal of 2 fiber combs commonly phase-locked to a narrow linewidth laser
Conclusion: frequency combs can be used to transfer laser linewidth at mHz level!
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3.11 大震災
K. Hosaka
H. Inaba
F.-L. Hong
D. Akamatsu
M. Yasuda
A. Onae
M. Aizawa