Observation of Squeezed States Generated by Four-Wave Mixing in an optical Cavity

1. Observation of Squeezed States Generated by Four-Wave Mixing in an optical Cavity 第二组 报告人：王康康

2. Contents： ①实验装置 ②实验内容 ③实验结果 ④结果讨论

3. 实验装置图 相当于非线性介质

4. 四波混频过程满足：

5. 实验内容 A measurement of four-wave —mixing gain. The smooth bell-shaped trace shows the signal resulting from the beam injected via shutter S1 when the pump is off and hence no four-wave —mixing gain is present. The modulated trace is taken with the pump on and is a direct measure of the four-wave-mixing gain.

7. Homodyne rms noise voltage at a fixed rf frequency as a function of the local oscillator phase with the squeeze cavity blocked (dim horizontal trace) and with the squeeze cavity open to the balanced detector and the pump light on (bright trace).

8. 实验结果 低于真空散射噪声水平， 表明了压缩态的产生 The deamplification below the total noise level is shown in Fig. 3, where the frequency is held constant and QLo is varied. The noise reduction below the vacuum fluctuation (shot noise) level at the maximum deamplification points is 0.3 dB or nearly 7% in power (with the small, constant amplifier-noise component taken into account).

9. 结果讨论： ⑴ It includes losses in the cavity and losses in the detection optics which degrade the observed degree of squeezing. ⑵实验中两个噪声源减小了可观测的压缩 ①spontaneous-emission radiation is present in the cavity because of absorption and reemission in the Lorentzian tails of the pumped Na atoms ———— 贡献噪声最低水平的约5% ② rapid phase variations ( >20 kHz) in the pump and LO light relative to the squeeze cavity are not corrected by the servo-controlled piezoelectric transducers used at present.

10. Thanks