L.Y. Gong

Signature of topological quantum phase transitions via Wigner-Yanase skew information

We apply the Wigner-Yanase skew information approach to analyze two typical models that exhibit a topological quantum phase transition. Based on the exact solutions of the ground states, the Wigner-Yanase skew information between two nearest sites for each of the two models is obtained. For the one-dimensional Kitaev chain model, the first-order derivative of the Wigner-Yanase skew information is non-analytical around the critical point. The scaling behavior and the universality are verified numerically. In particular, the skew information can also detect the factorization transition in such a model. For the two-dimensional Kitaev honeycomb model, the first-order derivative of the Wigner-Yanase skew information shows some singularities at the critical points where the system transits from the gapless phase to the gapped one. Our results suggest that the Wigner-Yanase skew information can serve as a good indicator of the topological phase transitions in these models and shed considerable light on the relationships between topological quantum phase transition and information theory.

Improving the Atmosphere Turbulence Tolerance in Holographic Ghost Imaging System by Channel Coding

Atmospheric turbulence (AT) severely cuts down the image resolutions of holographic ghost imaging (HGI) since orbital angular momentum (OAM) entangled states are associated with the spatial distribution of wave-functions. In this paper, we investigate the method to improve AT tolerance in HGI system. Since Reed-Solomon (RS) codes are important non-binary error correction codes which have strong correcting ability against noise, we use RS codes to develop a RS-coded HGI scheme. In order to verify the improvement quantitatively, we compute and compare the Peak Signal-to-Noise ratio (PSNR) of the reconstructed image in HGI without and with RS codes. The numerical results show that PSNRs go down quickly with the increase of the strength of turbulence, and they are improved greatly by using RS codes. For different grayscale objects, the results show that the improvement by RS codes is enhanced with the increasing correction ability, but it does not work for the same object by enlarging its grayscale to suit for more errors.

Measurement-induced disturbance near Anderson localization in one-dimensional systems

We study the localization transition in several typical one-dimensional single-particle systems by means of measurement-induced disturbance (MID). The results show that the MID presents a rapid drop around the boundary between the localized state and extended ones, and the corresponding first-order derivative exhibits a behavior of divergence around the critical point for deterministic on-site potential systems (e.g. the quasi-periodic model). These characteristics can capture a phase diagram as well as the traditional method. For the non-deterministic on-site systems (e.g. the random dimer model), the states around the resonant energies possess relatively large values for MID, which means that they are extended. In addition, as the random potential ϵ b exceeds the critical value, the states possessing a large MID vanish completely. These results show that MID can be useful in detecting localization transition in these typical one-dimensional systems.