All-optical BEC preparation method based on three-dimensional Raman sideband cooling

Abstract

The invention discloses an all-optical BEC preparation method based on three-dimensional Raman sideband cooling. The all-optical BEC preparation method comprises the steps: S1, preparing a cold atom group; S2, carrying out polarization gradient cooling; S3, carrying out three-dimensional Raman sideband cooling; cooling a group of atoms through a magneto-optical trap and preparing the atoms on a low hyperfine ground state; turning off the light and the magnetic field of the magneto-optical trap, opening an optical lattice, adiabatically loading each atom into each lattice point, and occupying agroup of vibration states according to the initial momentum; introducing a tiny magnetic field, enabling Zeeman splitting to be generated between different magneton energy level states, and cooling the atomic group to a dark state through pump light; S4, loading an optical dipole trap; S5, escaping, evaporating and cooling; and S6, achieving the escape evaporation cooling process by continuouslyreducing the depth of the optical trap, and finally preparing the BEC. The method has the advantages of being simple in principle, convenient to operate, capable of shortening preparation time and improving preparation efficiency and the like.

Description

technical field [0001] The invention mainly relates to the technical field of precision measurement, in particular to an all-optical BEC preparation method based on three-dimensional Raman sideband cooling. Background technique [0002] In 1925, Einstein extended Bose's statistical method for photons to particle systems with mass and discrete energy levels, and then jointly obtained the energy statistical distribution law of Bose-Einstein distribution, predicting the Bose-Einstein The existence of a Einstein condensate (BEC). With the continuous development of laser cooling gas atoms, researchers have the experimental conditions to start exploring the condensate in ideal gas atoms. In 1995, Anderson et al. first observed experimentally 87 A Bose-Einstein condensate of Rb atoms. Subsequently, the research groups of Davis, Bradley and Modugno realized the Bose-Einstein condensates of sodium, lithium and potassium respectively. [0003] At present, the preparation of BEC ad...

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Problems solved by technology

[0006] It can be seen that the above-mentioned existing methods all need magnetic traps, and this step takes a long time

That is to say, the above-mentioned classic BEC preparation is realized by magnetic trap loading combined with radio frequency evaporative cooling. This scheme has high requirements on magnetic traps, and the preparation time of BEC is long (usually greater than 20s), which is not conducive to the field of precision measurement. Applications

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