We report on the Lamb-Dicke spectroscopy of the doubly forbidden (6s(2))(1)S(0)↔(6s6p)(3)P(0) transition in (199)Hg atoms confined to a vertical 1D optical lattice. With lattice trapping of ≲10(3) atoms and a 265.6 nm probe laser linked to the LNE-SYRTE primary frequency reference we have determined the center frequency of the transition for a range of lattice wavelengths and at two lattice trap depths. We find the Stark-free (magic) wavelength to be 362.53(0.21) nm-essential knowledge for future use of this line in a clock with anticipated 10(-18) range accuracy. We also present evidence of the laser excitation of a Wannier-Stark ladder of states in a lattice of well depth 10E(R).
We report on the Lamb-Dicke spectroscopy of the doubly forbidden (6s(2))(1)S(0)↔(6s6p)(3)P(0) transition in (199)Hg atoms confined to a vertical 1D optical lattice. With lattice trapping of ≲10(3) atoms and a 265.6 nm probe laser linked to the LNE-SYRTE primary frequency reference we have determined the center frequency of the transition for a range of lattice wavelengths and at two lattice trap depths. We find the Stark-free (magic) wavelength to be 362.53(0.21) nm-essential knowledge for future use of this line in a clock with anticipated 10(-18) range accuracy. We also present evidence of the laser excitation of a Wannier-Stark ladder of states in a lattice of well depth 10E(R).
We present details on the ultraviolet lattice spectroscopy of the (6s2) 1S${}_{0}\ensuremath{\leftrightarrow}$ (6$s6p$) 3P0 transition in neutral mercury, specifically 199Hg. Mercury atoms are loaded into a one-dimensional vertically aligned optical lattice from a magneto-optical trap with an rms temperature of $\ensuremath{\sim}$60 $\ensuremath{\mu}$K. We describe aspects of the magneto-optical trapping, the lattice cavity design, and the techniques employed to trap and detect mercury in an optical lattice. The clock-line frequency dependence on lattice depth is measured at a range of lattice wavelengths. We confirm the magic wavelength to be 362.51(0.16) nm. Further observations to those reported by Yi et al. [Phys. Rev. Lett. 106, 073005 (2011)] are presented regarding the laser excitation of a Wannier-Stark ladder of states.
State-of-the-art optical clocks based on neutral atoms have already surpassed the world's best microwave atomic clocks in both accuracy and stability, paving the way to high-precision measurements of elementary aspects of nature, like the search for the drift of fundamental constants or the application of relativistic geodesy.These clocks operate with ensembles trapped in an optical lattice.Normally, high-power trapping laser fields induce a large AC Stark shift on the clock's transition frequency, as the clock states have different polarizabilities.A key feature of lattice clocks is the magic wavelength, for which the atomic polarizabilities of the clock states are equal, therefore compensating a differential frequency shift on the clock transition.In the periodic potential of the optical lattice, the energy spectrum of motional states features a band structure, analogous to electrons in a crystalline structure well-known from solid state physics.Within this band structure, atoms can tunnel between adjacent lattice sites.As a consequence from tunneling motion, the clock transition experiences a frequency shift and a broadening, which becomes pronounced in the shallow lattice regime.This work presents the first demonstration of a 24 Mg optical lattice clock including the precise determination of the frequency of the clock transition, its magic wavelength and its second-order Zeeman shift.Furthermore, the effect of tunneling in an optical lattice for magnesium has been extensively studied via optical spectroscopy of Bloch bands and substantiated with theoretical models, that were initially developed for a strontium optical lattice clock.Measuring lattice light induced frequency shifts of the clock transition for various lattice wavelengths and intensities, yielded a value of the magic wavelength of the 1 S 0 → 3 P 0 clock transition in 24 Mg of 468.463(207) nm.This value is in well agreement with a recent theoretical calculation of 468.45(23) nm, using a refined atomic structure model.The experimental value for the magic wavelength was independently verified with optical spectroscopy of Bloch bands carried out on the clock transition.Here, the AC Stark modified band structure is directly probed by a single frequency scan of the carrier resonance, featuring an asymmetric line shape, that is strongly dependent on the lattice wavelength.This technique demonstrates a novel method for the determination of the magic wavelength and could also be applied to other atomic species.In bosonic isotopes of alkaline earth(-like) elements, like 24 Mg, optical dipole excitation of the spin-forbidden 1 S 0 → 3 P 0 clock transition can be enhanced, e.g. by applying an external magnetic field.While these bosons are insensitive to first-order Zeeman shifts, the second-order Zeeman effect displays a dominant contribution to the clock's error budget.In this thesis, the magnetic polarizability β is measured to be -206.6(2.0)MHz/T 2 , consistent with a theoretical calculation, and the clock transition frequency was found to be 655 058 646 691(101) kHz.
We present an assessment of the (6s2) $^{1}S_{0}\ensuremath{\leftrightarrow}(6s6p)^{3}P_{0}$ clock transition frequency in 199Hg with an uncertainty reduction of nearly 3 orders of magnitude and demonstrate an atomic quality factor Q of $\ensuremath{\sim}{10}^{14}$. The 199Hg atoms are confined in a vertical lattice trap with light at the newly determined magic wavelength of $362.5697\ifmmode\pm\else\textpm\fi{}0.0011\text{ }\text{ }\mathrm{nm}$ and at a lattice depth of 20ER. The atoms are loaded from a single-stage magneto-optical trap with cooling light at 253.7 nm. The high Q factor is obtained with an 80 ms Rabi pulse at 265.6 nm. We find the frequency of the clock transition to be $1\text{ }128\text{ }575\text{ }290\text{ }808\text{ }162.0\ifmmode\pm\else\textpm\fi{}6.4(\mathrm{syst})\ifmmode\pm\else\textpm\fi{}0.3(\mathrm{stat})\text{ }\text{ }\mathrm{Hz}$ (i.e., with $\mathrm{\text{fractional uncertainty}}=5.7\ifmmode\times\else\texttimes\fi{}{10}^{\ensuremath{-}15}$). Neither an atom number nor second order Zeeman dependence has yet been detected. Only three laser wavelengths are used for the cooling, lattice trapping, probing, and detection.
We optically excite the electronic state 3s3p ^{3}P_{0} in ^{24}Mg atoms, laser cooled and trapped in a magic-wavelength lattice. An applied magnetic field enhances the coupling of the light to the otherwise strictly forbidden transition. We determine the magic wavelength, the quadratic magnetic Zeeman shift, and the transition frequency to be 468.46(21) nm, -206.6(2.0) MHz/T^{2}, and 655 058 646 691(101) kHz, respectively. These are compared with theoretical predictions and results from complementary experiments. We also develop a high-precision relativistic structure model for magnesium, give an improved theoretical value for the blackbody radiation shift, and discuss a clock based on bosonic magnesium.
The authors report on the recent progress in setting up a magic wavelength optical lattice for magnesium. At the magic wavelength for the1S0→3P0transition of Mg, which has been predicted to be at 463 nm, the differential AC Stark shift of the intercombination transition cancels out. Currently, the authors investigate to establish the optical lattice inside an optical resonator to enhance the trap depth and the loading of this lattice. Furthermore, the tight confinement of the atoms in the lattice will enable us to reach the Lamb-Dicke regime, allowing first order Doppler-free spectroscopy.