Browsing by Author "Yuan, Chun-Hua"

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    Effects of losses in the hybrid atom-light interferometer
    (OSA, 2016-08) Chen, Zhao-Dan; Yuan, Chun-Hua; Ma, Hong-Mei; Li, Dong; Chen, L. Q.; Ou, Z. Y.; Zhang, Weiping; Department of Physics, School of Science
    Collective atomic excitation can be realized by the Raman scattering. Such a photon-atom interface can form an SU(1,1)-typed atom-light hybrid interferometer, where the atomic Raman amplification processes take the place of the beam splitting elements in a traditional Mach-Zehnder interferometer. We numerically calculate the phase sensitivities and the signal-to-noise ratios (SNRs) of this interferometer with the method of homodyne detection and intensity detection, and give their differences of the optimal phase points to realize the best phase sensitivities and the maximal SNRs from these two detection methods. The difference of the effects of loss of light field and atomic decoherence on measure precision is analyzed.
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    Extracting the phase information from atomic memory by intensity correlation measurement
    (OSA, 2015-04) Guo, Jinxian; Zhang, Kai; Chen, L. Q.; Yuan, Chun-Hua; Bian, Cheng-ling; Ou, Z. Y.; Zhang, Weiping; Department of Physics, School of Science
    We demonstrate experimentally controlled storage and retrieval of the optical phase information in a higher-order interference scheme based on Raman process in 87Rb atomic vapor cells. An interference pattern is observed in intensity correlation measurement between the write Stokes field and the delayed read Stokes field as the phase of the Raman write field is scanned. This result implies that the phase information of the Raman write field can be written into the atomic spin wave via Raman process in a high gain regime and subsequently read out via a spin-wave enhanced Raman process, thus achieving optical storage of phase information. This technique should find applications in optical phase image storage, holography and information processing.
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    Intramode-correlation-enhanced phase sensitivities in an SU(1,1) interferometer
    (APS, 2017-09) Gong, Qian-Kun; Li, Dong; Yuan, Chun-Hua; Ou, Z. Y.; Zhang, Weiping; Physics, School of Science
    We theoretically derive the lower and upper bounds of quantum Fisher information (QFI) of an SU(1,1) interferometer whatever the input state chosen. According to the QFI, the crucial resource for quantum enhancement is shown to be large intramode correlations indicated by the Mandel Q parameter. The subtraction of photons from the squeezed vacuum state has the effect of increasing the average photon number of the new field state, as well as the intramode correlations. For example, for a coherent state ⊗ a squeezed vacuum state with a given fixed input mean number of photons as the input, if p photons are subtracted from the squeezed-vacuum state before inputting the SU(1,1) interferometer, the phase sensitivities can be improved due to the intramode-correlation increment.
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    SU(1,1)-type light-atom-correlated interferometer
    (APS, 2015-08) Ma, Hongmei; Li, Dong; Yuan, Chun-Hua; Chen, L. Q.; Ou, Z. Y.; Zhang, Weiping; Department of Physics, School of Science
    The quantum correlation of light and atomic collective excitation can be used to compose an SU(1,1)-type hybrid light-atom interferometer, where one arm in the optical SU(1,1) interferometer is replaced by the atomic collective excitation. The phase-sensing probes include not only the photon field but also the atomic collective excitation inside the interferometer. For a coherent squeezed state as the phase-sensing field, the phase sensitivity can approach the Heisenberg limit under the optimal conditions. We also study the effects of the loss of light field and the dephasing of atomic excitation on the phase sensitivity. This kind of active SU(1,1) interferometer can also be realized in other systems, such as circuit quantum electrodynamics in microwave systems, which provides a different method for basic measurement using the hybrid interferometers.