We report the observation of the magnetic-field-induced ( 5 d 10 6 s 2 ) S 0 1 − ( 5 d 10 6 s 6 p ) P 0 3 transition in a bosonic isotope of mercury, Hg 198 , realized in an optical lattice clock. We characterize this Hg 198 clock transition at 265.6 nm, determining key features such as the quadratic Zeeman shift, the probe light shift, and the magic frequency. We also report a comparison between the Hg 198 optical lattice clock and Sr 87 . In this comparison, the Hg 198 clock has a relative frequency stability of 6 × 10 − 16 / τ / s and a total relative systematic uncertainty of 6.9 × 10 − 16 . This comparison yields the first direct determination of the Hg 198 / Sr 87 optical frequency ratio: Hg 198 / Sr 87 = 2.629 315 734 684 118 1 , with the same relative uncertainty.
We report the observation of the magnetic-field-induced ( 5 d 10 6 s 2 ) S 0 1 − ( 5 d 10 6 s 6 p ) P 0 3 transition in a bosonic isotope of mercury, Hg 198 , realized in an optical lattice clock. We characterize this Hg 198 clock transition at 265.6 nm, determining key features such as the quadratic Zeeman shift, the probe light shift, and the magic frequency. We also report a comparison between the Hg 198 optical lattice clock and Sr 87 . In this comparison, the Hg 198 clock has a relative frequency stability of 6 × 10 − 16 / τ / s and a total relative systematic uncertainty of 6.9 × 10 − 16 . This comparison yields the first direct determination of the Hg 198 / Sr 87 optical frequency ratio: Hg 198 / Sr 87 = 2.629 315 734 684 118 1 , with the same relative uncertainty.
We report on a frequency ratio measurement of a 199Hg-based optical lattice clock referencing a 87Sr-based clock. Evaluations of lattice light shift, including atomic-motion-dependent shift, enable us to achieve a total systematic uncertainty of $7.2\ifmmode\times\else\texttimes\fi{}{10}^{\ensuremath{-}17}$ for the Hg clock. The frequency ratio is measured to be ${\ensuremath{\nu}}_{\mathrm{Hg}}/{\ensuremath{\nu}}_{\mathrm{Sr}}=2.629\text{ }314\text{ }209\text{ }898\text{ }909\text{ }60(22)$ with a fractional uncertainty of $8.4\ifmmode\times\else\texttimes\fi{}{10}^{\ensuremath{-}17}$, which is smaller than the uncertainty of the realization of the International System of Units (SI) second, i.e., the SI limit.
In this poster, we will describe the key developments made in our setup to switch from a clock using fermionic isotopes of mercury to bosonic isotopes of mercury. Initially, we must establish the magnetic field necessary for the quenching method, i.e. to induce the bosonic clock transition. We have introduced a technique to create a strong magnetic field during the probing time. Furthermore, we have enhanced our control over the magnetic environment. Secondly, as we aim to observe the clock transition, we have had to enhance the capabilities of our ultrastable light generation. This enhancement was crucial to provide a tuning range sufficient to reach the frequency of any of the five stable bosonic isotopes while maintaining spectral quality. Thirdly, we calculated the theoretical Rabi pulsation for a clock utilizing bosonic isotopes, determining that we must increase the the probe laser power to achieve a sufficiently large Rabi pulsation. This adjustment is necessary to facilitate the initial exploration of the transition.
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 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.
We report direct laser spectroscopy of the $^{1}S_{0}\mathrm{\text{\ensuremath{-}}}^{3}P_{0}$ transition at 265.6 nm in fermionic isotopes of neutral mercury in a magneto-optical trap. Measurements of the frequency against the LNE-SYRTE primary reference using an optical frequency comb yield $1\text{ }128\text{ }575\text{ }290\text{ }808.4\ifmmode\pm\else\textpm\fi{}5.6\text{ }\text{ }\mathrm{kHz}$ in 199Hg and $1\text{ }128\text{ }569\text{ }561\text{ }139.6\ifmmode\pm\else\textpm\fi{}5.3\text{ }\text{ }\mathrm{kHz}$ in 201Hg. The uncertainty, allowed by the observation of the Doppler-free recoil doublet, is 4 orders of magnitude lower than previous indirect determinations. Mercury is a promising candidate for future optical lattice clocks due to its low sensitivity to blackbody radiation.
We present experimental results for an optical lattice clock operating on the1S0harr3P0transition in88Sr, which is excited with the technique of magnetic field-induced spectroscopy To reduce the complexity of the setup we have developed a set of new experimental techniques that greatly simplifies the clock spectroscopy in Sr atoms. First, we developed a method for finding the clock transition that removes the need for extensive frequency metrology hardware and optical frequency combs. This technique exploits a near coincidence in the atomic wavelengths of the1S0harr3P0clock and1S0harr3P1second stage cooling transitions in Sr, which are only 5 THz far apart. This coincidence enables the use of an optical (transfer) cavity to reference the frequency of the clock transition relative to that of the much stronger coolign transition Second, all laser sources in the experimental setup are based on semiconductor technology, which greatly reduces the complexity of the apparatus. With this setup, about 10488Sr atoms are trapped in a 1D lattice formed by 200 mW of radiation tuned near the magic wavelength at 813 nm. Preliminar uncertainty budget for our optical lattice clock is also presented, with particular attention to density dependent collisions, which led to an unexpectedly high signal contrast for long interaction times.