| Budget Amount *help |
¥2,300,000 (Direct Cost: ¥2,300,000)
Fiscal Year 1993: ¥800,000 (Direct Cost: ¥800,000)
Fiscal Year 1992: ¥1,500,000 (Direct Cost: ¥1,500,000)
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| Research Abstract |
The purpose of this project is to construct a new type of non-absorptive photo detection system which utilizes the light shift of atomic resonance line. By extending this system, we may be able to achieve quantum non-demolition measurement of photon numbers. The light shift due to virtual (non-absorbtive) transition by off-resonant light is proportional to the light intensity or the photon number. By measuring the shift, we can infer the light intensity without absorbing the light.
In normal conditions, the amount of shift is so tiny compared with the transition frequency itself and also with the natural linewidth that it is almost impossible to measure it directly.
If, however, we use atoms with Zeeman sublevels in the ground state and circularly polarized light as the shifting source, then the shift can be measured as a relative deviation of ground state sublevels.
We utilized the rf resonance, the Hanle effect, and the parametric resonance to measure the relative level shift in the ground state.
In particular, in the third system, we separated the following three regions in space ; 1) state preparation region, 2) interaction region, 3) state reading region ; which enabled us to have clear correspondence between the theoretical model and the experimental setup. The drawback of the system is reduction of the sensitivity because the probability for a thermal atom to fly through the above three region in order is small.
We are hoping that this problem will be overcome when we use laser-cooled atomic beam by which controlled and prolonged interaction is achieved. For this purpose, we have developed a spin-polarized atomic trap.
In reference to the above experiment, we have studied on the Galilei invariance of classical and quantum waves.
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