Two-photon interferences on a silica-on-silicon chip with telecom-band photon pairs generated in a fiber.

We report two-photon interferences on a silica-on-silicon chip of Mach-Zehnder interferometer using telecommunication-band correlated photon pairs. The photon pairs were generated by spontaneous four-waving mixing process in a dispersion-shifted fiber. The integrated chip, which was fabricated by standard silica-on-silicon planar lightwave circuit technology, contained a Mach-Zehnder interferometer with a thermo-optic phase shifter. The insertion loss of the interferometer was less than 1 dB. We demonstrated two-photon interferences with both degenerate- and non-degenerate-frequency photon pairs on the Mach-Zehnder interferometer chip. A high fringe visibility was achieved in the interference with nondegenerate-frequency photons. Properties of quantum interference were demonstrated in the interference with degenerate-frequency photon pairs, which is an important way to manipulate the quantum state. These results show great potential of silica-on-silicon photonic chips in applications for the fiber-chip scheme in quantum networks.

Expression pattern and functional analysis of the two RING box protein RBX in spermatogenesis of Chinese mitten crab Eriocheir sinensis.

Studies in E. sinensis have shown that ubiquitination mediated by Cullin-RING E3 ligases (CRLs) plays important roles in spermatogenesis. In other species, CRLs are also essential in cell cycle progression, DNA replication, signal transduction, gene transcription, and development. The catalytic RING component, the RING box protein, is an important part of CRLs. However, there have been few studies on CRLs in crustaceans. In this study, we cloned two RING box protein genes from the Chinese mitten crab, Eriocheir sinensis, termed Es-RBX1 and Es-RBX2 The full length Es-RBX1 cDNA comprises 741 nucleotides, and encodes a protein of 124 amino acid residues, whereas the Es-RBX2 cDNA comprises 1325 nucleotides, and encodes a protein of 110 amino acid residues. Bioinformatics analysis showed that the domains and structure of the RBX proteins have been highly conserved during evolution. Quantitative real-time polymerase chain reaction and western blotting showed that Es-RBX1 is highly expressed in the testis, particularly during the spermatocyte stage, whereas Es-RBX2 did not show specific expression in the male reproductive system. Furthermore, Es-RBX1 is mainly distributed in the nucleus, and changed its location with the development of the nucleus. Co-immunoprecipitation showed that Es-RBX1 could bind Cullin4. These results suggested that Es-RBX1 plays a key role in spermatogenesis of E. sinensis though forming a complex with Cullin4.

Design and fabrication of a low-loss and asymmetric 1 × 5 arbitrary optical power splitter.

In this paper, a low-loss and wavelength-insensitive asymmetric 1×5 arbitrary optical power splitter is designed and optimized, which is composed of a three-branch and two Y-branch elements. A low-loss and wavelength-independent arbitrary 1×5 optical power splitter can be obtained. Asymmetric 1×5 optical power splitters of different output ratios are fabricated using silica-based planar lightwave circuit (PLC) technology on a 6-inch quartz substrate. The measured results show that the ILoutput1, ILoutput2∼5, UNIFoutput2∼5, PDL, and WDL of the output ratio 33%:67%, 50%:50%, and 95%:5% are less than (5.302 dB, 8.483 dB, 0.422 dB, 0.191 dB, 0.345 dB), (3.46 dB, 9.71 dB, 0.28 dB, 0.119 dB, 0.231 dB), and (1.52 dB, 14.15 dB, 0.44 dB, 0.366 dB, 0.561 dB), respectively, in the wavelength of 1.27 µm, 1.31 µm, 1.49 µm, 1.55 µm, and 1.625 µm.