Thulium atom for optical lattice clock applications. N. Kolachevsky. D. Sukachev E. Kalganova G.Vishnyakova S. Fedorov V. Sorokin. P.N. Lebedev Physical Institute National Metrology Institute VNIIFTRI Moscow Institute of Physics and Technology. Thulium Project.
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D. SukachevE. Kalganova G.VishnyakovaS. FedorovV. Sorokin
P.N. Lebedev Physical Institute
National Metrology Institute VNIIFTRI
Moscow Institute of Physics and Technology
Using of Thulium atoms as a candidate for optical clocks was first proposed in 1997 by S. Kanorsky (P.N. Lebedev Physical Institute). Laser cooling scheme and the candidate for clock transition at 1.14 mm were suggested.
Progress started after 2007 when laser system for a first-stage cooling was developed.
We will report on recent progress at P.N. Lebedev Physical Institute
Electronic structure of lanthanides (Yb, Dy, Er, Tm) is similar to alkali-earth elements (Ca, Sr, Mg) due to a closed outer electronic s-shell.
Laser cooling of lanthanides is more challenging because of the absence of closed strong cooling transitions. All of strong transitions possess decay channels.
Requirements for an efficient laser cooling transition:
Comparison of two identical
Yb clocks is performed at
NIST, 2013 in the group of
N. Hinkley at al., Science Vol. 341 no. 6151 pp. 1215-1218 (2013)
T. Lahaye,et al., Phys Rev Lett. 080401 (2008)
W. S. Bakr, J. I. Gillen, A. Peng, S. Foelling, M. Greiner
Nature 462, 74-77 (2009)
Vacancies in the hollow 4f-shell (e.g. Er, Dy, Tm) provide big magnetic moment in the ground state.
Magnetic moment of Dy equals 10 mB, of Er 6mB. Strong dipole-dipole interactions between ground state atoms. Dipole-interacting condensates and quantum simulators.
Feshbach resonance in Er
M. Lu, N.Q. Burdick, S.H. Youn, and B.L. Lev Phys. Rev. Lett. 107 190401 (2011)
K. Aikawa et al. Phys. Rev. Lett. 108 210401 (2012)
Large J causes large magnetic moments of the ground state
Similar polarizabilities of the ground-state fine structure components
M1 transition =1.14 m, ~ 1 Hz
(V.D. Ovsyannikov, 2010 )
To what extent the transition frequency remains unperturbed?
Because of the closed 6s2 shell, the inner shells are shielded to the external perturbations.
The shileding was first demonstrated experimentally by E.B. Alexandrov in 1983
J. Doyle at al. measured for He-Tm collisions (Nature, 2004)
For Tm-Tm collisions in specific magnetic state the shielding disappears (PRA, 2010)
E.B.Aleksandrov et al., Opt. Spektrosk., 54, 3, (1983)
C.I. Hancox et al. Nature 431, 281 (2004)
C.B.Connolly et al., Phys. Rev. A 81, 010702 (2010)
in the MOT
1= 22(6) s-1
5 times more atoms
Ballistic expansion of the atomic cloudto measure temperature
TD = 240 K
Tmin = 25 K
Due to specific level structure of Tm atom (degeneracy of the Landé g-factors) sub-Doppler mechanism IS EFFICIENT even in the presence of magnetic field
First stage cooling at 410 nm
Second stage cooling at 530.7 nm
Frequency-doubled laser diode
radiation is used
Ultra stable cavitites
Instability~ 10-15 (1-100 s)
Second stage cooling: 1.06 mm
Clock laser: 1.14 mm
Clock laser scan @ 1.14 mm
Cloud spectroscopy T= 100 mK
FWHM(P0) = 0.5 MHz
Optical lattice needed!
Fraction of power in a single frequency >95%
Saturation absorption signal in Tm
Tm cloud trapped by diode laser radiation
Injection locking gives up to 150 mW @ 410.6 nm