We present two robust quantum secure direct communication (QSDC) schemes with a quantum one-time pad over a collective-noise channel. Each logical qubit is made up of two physical qubits and it is invariant over a col...We present two robust quantum secure direct communication (QSDC) schemes with a quantum one-time pad over a collective-noise channel. Each logical qubit is made up of two physical qubits and it is invariant over a collective-noise channel. The two photons in each logical qubit can be produced with a practically entangled source, i.e., a parametric down-conversion source with a beta barium borate crystal and a pump pulse of ultraviolet light. The information is encoded on each logical qubit with two logical unitary operations, which will not destroy the antinoise feather of the quantum systems. The receiver Bob can read out the sender's message directly with two single-photon measurements on each logical qubit, instead of Bell-state measurements, which will make these protocols more convenient in a practical application. With current technology, our two robust QSDC schemes are feasible and may be optimal ones.展开更多
Crystals of the low temperature phase b-Ba3Y(BO3)3 have been synthesized by the flux method. The structure of the title compound crystallizes in the hexagonal system, space group P63cm with the following parameters: a...Crystals of the low temperature phase b-Ba3Y(BO3)3 have been synthesized by the flux method. The structure of the title compound crystallizes in the hexagonal system, space group P63cm with the following parameters: a = 9.416(3), c = 17.536(8) ? V = 1346.6(8) ?, Ba3YB3O9, Mr = 677.36, Z = 6, Dc = 5.012 g/cm3, l(MoKa) = 0.71073 ? m = 19.409 mm-1, Flack parameter = 0.02(3), F(000) = 1764, R = 0.0714 and wR = 0.1696 for 1076 observed reflections with I > 2s(I). The compound contains two sets of YO6 octahedra, four sets of BaO9 polyhedra and three sets of BO3 planar triangles.展开更多
基金supported by the Natural Science Foundation of Jiangsu Provincial Universities (Grant No. 10KJB180004)the National Natural Science Foundation of China (Grant No. 10847147)
文摘We present two robust quantum secure direct communication (QSDC) schemes with a quantum one-time pad over a collective-noise channel. Each logical qubit is made up of two physical qubits and it is invariant over a collective-noise channel. The two photons in each logical qubit can be produced with a practically entangled source, i.e., a parametric down-conversion source with a beta barium borate crystal and a pump pulse of ultraviolet light. The information is encoded on each logical qubit with two logical unitary operations, which will not destroy the antinoise feather of the quantum systems. The receiver Bob can read out the sender's message directly with two single-photon measurements on each logical qubit, instead of Bell-state measurements, which will make these protocols more convenient in a practical application. With current technology, our two robust QSDC schemes are feasible and may be optimal ones.
基金The project was supported by the Key Project of Science and Technology of Fujian province (2001H107) and the National Natural Science Foundation of China (N0. 50272066)
文摘Crystals of the low temperature phase b-Ba3Y(BO3)3 have been synthesized by the flux method. The structure of the title compound crystallizes in the hexagonal system, space group P63cm with the following parameters: a = 9.416(3), c = 17.536(8) ? V = 1346.6(8) ?, Ba3YB3O9, Mr = 677.36, Z = 6, Dc = 5.012 g/cm3, l(MoKa) = 0.71073 ? m = 19.409 mm-1, Flack parameter = 0.02(3), F(000) = 1764, R = 0.0714 and wR = 0.1696 for 1076 observed reflections with I > 2s(I). The compound contains two sets of YO6 octahedra, four sets of BaO9 polyhedra and three sets of BO3 planar triangles.
