In the general bipartite quantum system m ⊗ n, Wang et al. [Y.-L Wang et al., Phys. Rev. A 92, 032313 (2015)] presented 3(m + n) − 9 orthogonal product states which cannot be distinguished by local operations and classical communication (LOCC). In this paper, we aim to construct less locally indistinguishable orthogonal product states in m ⊗ n. First, in 3 ⊗ n(3 < n) quantum system, we construct 3n − 2 locally indistinguishable orthogonal product states which are not unextendible product bases. Then, for m ⊗ n(4 ≤ m ≤ n), we present 3n + m − 4 orthogonal product states which cannot be perfectly distinguished by LOCC. Finally, in the general bipartite quantum system m ⊗ n(3 ≤ m ≤ n), we show a smaller set with 2n − 1 orthogonal product states and prove that these states are LOCC indistinguishable using a very simple but quite effective method. All of the above results demonstrate the phenomenon of nonlocality without entanglement.

The terahertz wave is a kind of electromagnetic waves which locates between millimeter waves and infrared lightwaves, and the frequency range is 0.14THz~10THz. Terahertz is used as a carrier wave to communicate with each other because it has large bandwidth which can support Gbps wireless data rates. Therefore, terahertz communication technologies become research hot spots in recent years. However, its still rare in MAC protocol of terahertz ultra-high data-rate wireless networks at present. In order to realize wireless access of ultra-high data-rate under the condition of terahertz carrier frequency, a novel MAC protocol is proposed in this paper. The improved MAC protocol which makes the maximum data rates reach up to 10Gbps or higher is designed by new MAC control mechanisms, new time-slots allocation schemes and new superframe structure. Theoretical analysis and simulation results show that the new proposed MAC protocol of terahertz ultra-high data-rate wireless networks can operation normally, and the maximum data rate can reach up to 19.2Gbps. This maximum data rate is 2 times higher than 5.78 Gbps which IEEE 802.15.3c can achieve.

Sandy conglomerate reservoir has the characteristics of poor sorting, complex pore structure, heterogeneity, and so sandy conglomerate oil layer is difficult to identify. In this paper, based on symmetrical effective medium conductance theory and poor sorting of grains of sandy conglomerate, a symmetrical effective medium resistivity model for sandy conglomerate reservoir is established by dividing sandy conglomerate reservoir into three components, including a non-conductive matrix, gas and water. The log data is processed and interpreted with the proposed model, and the interpretation result compared with gas production test data. It shows that the model is applicable to evaluate the fluid property of sandy conglomerate reservoirs.

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