H. Wang et al., SUB-SHOT-NOISE MEASUREMENT FOR SLIGHT ABSORPTION, Science in China. Series A, Mathematics, Physics, Astronomy & Technological Sciences, 41(5), 1998, pp. 534-540
Sub-shot-noise measurement for slight absorption is experimentally ach
ieved with the twin beams of quantum correlation. The improvement in s
ignal-to-noise ratio of 2.5 dB relative to the SNL is obtained. The ex
perimental results demonstrate the predictions of the semi-classical t
heory.