title: Spin squeezing: transforming one-axis twisting into two-axis twisting.
abstract: Squeezed spin states possess unique quantum correlation or entanglement and are significantly promising for advancing quantum information processing and quantum metrology. In recent back-to-back publications [C. Gross et al., Nature (London) 464, 1165 (2010) and Max F. Riedel et al., Nature (London) 464, 1170 (2010)], reduced spin fluctuations are observed leading to spin squeezing at -8.2 and -2.5 dB, respectively, in two-component atomic condensates exhibiting one-axis-twisting interactions. The noise reduction limit for the one-axis twisting scales as ∝1/N(2/3), which for a condensate with N∼10(3) atoms is about 100 times below the standard quantum limit. We present a scheme using repeated Rabi pulses capable of transforming the one-axis-twisting spin squeezing into the two-axis-twisting type, leading to Heisenberg limited noise reduction ∝1/N or an extra tenfold improvement for N∼10(3).
authors.affiliation: Department of Physics, Beijing Jiaotong University, People's Republic of China.
authors.forename: Y C
authors.initials: YC
authors.lastname: Liu
authors.forename: Z F
authors.initials: ZF
authors.lastname: Xu
authors.forename: G R
authors.initials: GR
authors.lastname: Jin
authors.forename: L
authors.initials: L
authors.lastname: You