| Single atoms have important applications in the fields of the quantum register,single-photon source,etc.The internal degree of freedom of single atoms can provide qubits for quantum information processing.In addition,the entanglement between single atoms and single photons plays an important role in quantum information processing and quantum computing.A single-photon source based trapped single atom in micro-scale optical tweezers has the advantages of matching the atomic transition line,narrow bandwidth,and almost no interaction of atoms with external light and electric fields.Due to its long radiation lifetime,large orbital radius,and strong inter-atomic interactions,Rydberg atom has important applications in quantum optics,accurate measurements,quantum information processing,etc.In the thesis,we discuss the characteristics of a single ground-state atom or Rydberg atom trapped in optical tweezer,the action of laser intensity fluctuation of the optical tweezer laser beam on the ground-state atom trapping lifetime and the extension of trapping lifetime of a trapped atom.Calculate the light shift of trapped atom in the optical tweezer with different polarization,and magic optical tweezer of Rydberg atom.The main work shown in the thesis are as follows:I.High probability loading single atoms in the magneto-optical trap.In the experiment,load a single atom in the magneto-optical trap and then transfer the atom into an optical tweezer.It is necessary to load single atoms into the magneto-optical trap efficiently in order to load single atoms into optical tweezer with high probability.A trigger loop is used to control the fourth-order magnetic field gradient of the magneto-optical trap accurately.The loading rate of a single atom in the magneto-optical trap increased from 28.4% to 80.2%.II.Prolongation of trapping lifetime of a single atom in an optical tweezer.We discuss the factors that affect the trapping lifetime of a single atom in optical tweezer,especially the heating parametric heating process of the intensity fluctuations of the optical tweezer beam.Single-atom couples with the intensity noise resonating with the trap frequency and its double frequency of optical tweezer,then get heated and escape from the optical tweezer.We use the feedback control system to stabilize the intensity fluctuation of the optical tweezer laser beam by controlling the diffraction efficiency of the acousto-optic modulator.The intensity fluctuation of the 1064 nm optical tweezer is suppressed from ± 3.360% to ± 0.064%.The suppression bandwidth reaches 33 k Hz,which covers the axial trap frequency and its double frequency of the optical tweezer.The trapping lifetime of a single atom in optical tweezer extended from 4.04 s to 6.34 s.III.The action of laser polarization on the light shift of a single atom in an optical tweezer.There is a deviation between the calculation and experimental result of the wavelength of the magic tweezer of the cesium 6S1/2(Fg = 4,m F = +4)-6P3/2(Fg = 5,m F = +5)transfer,excluding the instability of the experimental system and measurement errors.It is because that the polarization of the optical tweezer beam becomes an elliptical polarization beam when passing through the focusing lens assembly.We calculate the action of elliptically polarized laser on the light shift of the atom in the optical tweezer,and measure the polarization change of the optical tweezer beam before and after passing through the focusing lens assembly.The degree of polarization of the parallel laser beam before passing through the lens assembly is 2542: 1,and 2208: 1 after.IV.The pre-research on magic tweezer of Rydberg atom.The pre-research on magic tweezer of cesium 43S1 / 2-70S1 / 2 and 90S1 / 2,including calculating the polarizability and scattering rate of atoms in the tweezer and discussion about the choice of auxiliary states,etc.Besides,it brings out a proposal for an experimental scheme of magic tweezer of Rydberg atom,including the generation of ground-state atoms,cascade two-photon transition Rydberg excitation,the detection of Rydberg atom,and the measurement of magic tweezer of Rydberg atom. |
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