Laser-cooling in noisy quadrature of squeezed vacuum for cesium fountain clock

摘要

In this paper we report that the noisy quadrature, a undesirable feature of the squeezed light, could be effectively used in realizing higher cooling force in the Cs fountain clock. We know that the laser cooling is basically the result of the combination of undesirable phenomena like light shift, Doppler shift and polarization gradient. We establish in this paper that the noisy quadrature, a unwelcome feature of the squeezed light is useful in achieving larger cooling force. When the atoms interact with the squeezed vacuum, they decay into two quadratures which respectively have quantum noise below and above the normal vacuum fluctuations. The noisy quadrature corresponds to the faster decay rate. On subjecting the Cs atoms to the noisy quadrature of the squeezed vacuum, superimposed with the squeezed coherent light, the cooling force is increased. The use of the noisy quadrature of the squeezed vacuum for obtaining larger cooling force and the temperatures much below the Doppler limit, without resorting to large detuning of the driving field, is a novel idea discussed in this paper. We report that the S/N of the clock signal may also be improved with the squeezed light.