Application Of Clock Transition Spectrum And Study Of Floquet Rabi Spectrum Of The Strontium Optical Lattice Clock

In February 2022,published in the journal Nature,an article on the cover shows the scale of 10^-21 strontium atomic optical lattice clock measurement accuracy,by measuring the atoms in the same optical lattice height difference is 1 mm two clouds of atoms of different speeds,the passage of time in small spatial scales to verify the validity of Einstein’s general theory of relativity.The high measurement accuracy of the strontium atomic optical lattice clock lays a foundation for finding new physics beyond the Standard Model,establishing the new technologies in the field of measurement and navigation,and redefining the"second"in the International System of Units in the future.Based on the experimental platform of strontium atomic optical lattice clock,the following research contents are carried out:the zero-temperature drift point of the ultra-stable optical reference cavity（ULE cavity）is measured by using high resolution clock transition spectrum;The Floquet rabi spectrum is studied by using the period-driven optical lattice technique.In a shallow optical lattice,the quantum tunneling phenomenon has been successfully observed by observing the splitting of the clock transition transition spectrum.The specific research content and results are as follows:（1）Through the detailed theoretical analysis of the two-level system in the optical lattice,the band structure of atoms in the one-dimensional optical lattice is obtained.The spectrum of the clock transition carrier transition are further analyzed and the effects of different atomic populations on the spectrum are considered.The key experimental parameters,such as the axial and radial temperatures of atoms in the lattice,the rabi frequency,and the angle between clock laser and lattice light,are obtained by fitting the clock transition spectra of strontium atomic optical lattice with the theoretical linear expression of clock transition spectra.By studying the spectrum of cold atom in one-dimensional optical lattice,it is not only verified that the effective temperature of atom in optical lattice obeys boltzmann distribution,but also provides a theoretical basis for the extraction of key system parameters in the experiment,and promotes the understanding of atomic transition spectra in one-dimensional optical lattices.（2）The zero-temperature drift point of ULE cavity in 698 nm ultra-stable narrow linewidth laser system is measured by using high-resolution clock transition spectral.The optimal zero-temperature drift point of the ultra-stable optical reference cavity used in the experiment is 30.63°C and the measurement error is 0.42°C.At the zero-temperature drift point,the linear drift rate of 698 nm ultra-stable narrow-line clock laser is 0.15 Hz/s by using the closed-loop locking method of the optical clock.The determination of zero-temperature drift point of ULE cavity in 698 nm ultra-stable narrow linewidth laser system is helpful not only to improve the instability of 698 nm ultra-stable narrow linewidth laser system,but also to improve the instability of ⁸⁷Sr optical lattice clock system.In addition,the atomic transition spectral measurement method has the advantages of higher accuracy and more convenient experimental operation compared to other methods.（3）On the platform of the ⁸⁷Sr optical lattice clock,the experimental models of single-parameter modulation and double-parameter modulation are established theoretically,and the correctness of the theoretical model is verified through experiments.In the single-parameter modulation experiment,the possibility of accurately manipulating a Floquet sideband is demonstrated by adjusting the modulation frequency and amplitude.In the two-parameter modulation experiment,an obvious"Floquet photon"interference effect is observed by fine-tuning the relative phase between the two modulations additional on the lattice laser and clock laser.The successful implementation of the Floquet design on the strontium optical clock experiment platform opens a new way for the study of quantum simulation,precision spectral measurement and quenching process on the strontium optical clock platform.（4）On the platform of one-dimensional ⁸⁷Sr atomic optical lattice clock,the narrow-linewidth ¹S₀（|g）)-³P₀（|e）)transition（that is,the clock transition）is excited by an ultra-stable and ultra-narrow linewidth 698 nm laser,and the distribution of strontium atoms in the specific quantum state is prepared.In the deep optical lattice,after the cold ⁸⁷Sr atoms in preparation reach the|e,n_z=1)state,the lattice depth of the optical lattice is adiabatically reduced.Then,the carrier-sideband resolved clock transition spectral is detected in the shallow optical lattice.The obvious splitting of the carrier spectral is observed from the clock transition spectral,which indicates that the strontium atoms have an obvious quantum tunneling phenomenon between the adjacent lattice sites of the optical lattice.These researches not only help to improve the uncertainty of optical lattice clocks,but also lay a foundation for observing the spin-orbit coupling effect of fermions in the optical lattices and the experimental research on the suppression of clock transition tunneling spectrum by Floquet theory.