论文部分内容阅读
We report the experimental generation of a squeezed vacuum at frequencies ranging from 2.5 kHz to 200 kHz that is resonant on the cesium D2 line by using a below-threshold optical parametric oscillator (OPO).The OPO is based on a periodically-poled KTiOPO4 (PPKTP) crystal that is pumped using a bow-tie four-mirror ring frequency doubler.The phase of the squeezed light is controlled using a quantum noise locking technique.At a pump power of 115 mW,maximum quadrature phase squeezing of 3.5 dB and anti-squeezing of 7.5 dB are detected using a home-made balanced homodyne detector.This squeezed vacuum at an atomic transition in the kilohertz range is an ideal quantum source for quantum metrology of enhancing measurement precision,especially for ultra-sensitive measurement of weak magnetic fields when using a Cs atomic magnetometer in the audio frequency range.