Heterodyne-detection study of the topological phase in optical two-level systems

Changqing C. Cao, Xiaodong Zeng, Yili Zheng +2 more

A photorefractive adaptive optical heterodyne detection system is proposed. Its principle is introduced and typical numerical calculation is illustrated, which includes the reference beam output power and minimum detectable signal power versus system global power ratio, the effect of crystal coupling strength on reference beam output power and minimum detectable signal power, and the minimum detectable signal power versus nonlinear coupling strength. Several key factors which affect the system characteristics strongly are pointed out. In the proposed system, only one photorefractive crystal is used to attain optical heterodyne detection. The system features simple structure, low noise and high responsibility. It also answers two key questions of heterodyne detection: 1) phase distortion; 2) coherent length of light source.

Ichiro Sakuraba

Chengdong He, Zejian Ren, Entong Zhao +2 more

Anders Bolund, Klaus Mølmer

We study the dynamics of an atomic two-level system decaying by spontaneous emission of light. Subject to continuous detection of the radiated field, the system tends with certainty to the ground state in the long time limit, but at initial times the excited-state population exhibits nontrivial stochastic behavior. Employing methods from Ito calculus, we characterize this behavior in case of unit efficiency detection, and we show, for example, that the emitter, as a result of in-phase homodyne measurements, may become fully excited during the decay process while heterodyne and out-of-phase homodyne measurements do not drive the atom completely into the excited state.

S. Le Boiteux, Daniel Bloch, M. Ducloy

Liangen Ding, Ziyi Bi, Long-Sheng Ma

Optical heterodyne spectroscopy is one of the ultrasensitive and high resolution laser spectroscopies. During past years, it has extended from saturation absorption to two-photon transitions in a three level quantum system of atoms and ions. The particularly interesting case is the modulation transfer spectroscopy, where the optical heterodyne detection is performed via nearly degenerate four-wave mixing (NDFWM) in the nonlinear medium. In this report, the modulation transfer spectroscopy is used to observe the optical heterodyne saturation absorption and two-photon transition spectra simultaneously in Na2 without Doppler background. The line shapes of optical heterodyne signal are discussed in detail.