Spectral compression of single photons

Photons are critical to quantum technologies since they can be used for virtually all quantum information tasks: in quantum metrology, as the information carrier in photonic quantum computation, as a mediator in hybrid systems, and to establish long distance networks. The physical characteristics of photons in these applications differ drastically; spectral bandwidths span 12 orders of magnitude from 50 THz for quantum-optical coherence tomography to 50 Hz for certain quantum memories. Combining these technologies requires coherent interfaces that reversibly map centre frequencies and bandwidths of photons to avoid excessive loss. Here we demonstrate bandwidth compression of single photons by a factor 40 and tunability over a range 70 times that bandwidth via sum-frequency generation with chirped laser pulses. This constitutes a time-to-frequency interface for light capable of converting time-bin to colour entanglement and enables ultrafast timing measurements. It is a step toward arbitrary waveform generation for single and entangled photons.Comment: 6 pages (4 figures) + 6 pages (3 figures

The Effect of Vero Cells Co-Culture on In Vitro Maturation of Bovine Immature Oocytes and Further Embryo Development

Objective: This study was carried out to examine the effect of vero cells co-culture on developmental competence of immature oocytes.Materials and Methods: Bovine cumulus-oocyte-complexes (COCs) were matured in either presence or absence of vero cells. Matured oocytes were inseminated and cultured for up to nine days. Cleavage percentages were recorded on day two post insemination (pi). Embryos were evaluated on daily basis till 9pi. Expanding/expandedand hatching/hatched blastocysts were used for cell number assay.Results: The results indicated a significantl increase in the cleavage number in oocytes matured in the presence of vero cells than that of the control (86% vs. 76%). The percentages of advanced embryos appear to be greater on a daily basis in COCs matured in the presence of vero cells compared to those of the control. However,these differences were not significant. Blastocysts derived from COCs matured in the presence of vero cells had a significantly higher number of inner cell mass, trophectoderm and total cell number in expanding/expand and hatching/hatched embryos in comparison to those of the control.Conclusion: Results confirm that co-culture of bovine COCs, during in vitro maturation,enhances the potential for cleavage and for producing blastocysts with higher quality

Effects of cilostamide and/or forskolin on the meiotic resumption and development competence of growing ovine oocytes selected by brilliant cresyl blue staining

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Selection of the Most Appropriate Medium for Assessing Motility and DNA Uptake of Bovine Spermatozoa

Objective: The aim of this study was to select the best medium to maintain spermmotility during sperm-DNA incubation and assess the DNA uptake by spermatozoaof Iranian Holstein bulls and its effects on sperm motility.Materials and Methods: frozen sperms from an Iranian Holstein bull were thawedand centrifuged. Motile sperms were separated through Puresperm gradient(40/80%) followed by two times washing in SP-TALP medium. Then, sperms werewashed once (PBS, Opti-MEM and SP-TALP) and incubated with DNA in each mediafollowed by sperm motility estimation. The plasmid pEGFP-C1 was linearizedand incubated with sperms at 37°C for 1 hour. Sperm-DNA mixture was treated withDNase I and the sperm pellet was washed with PBS.DNA extraction from sperms and supernatants from the last washing were used astemplate for PCR. Data was analyzed using SAS package and mean comparisonsbetween sperm motility in different media were performed.Results: Sperm motility after incubation in PBS, Opti-MEM and SP-TALP were40(±2.89), 2(±1.53) and 54(±4.41) percent, respectively. PCR results from transfectedsperms indicated that EGFP transgene internalized into the bovine spermsand DNaseI treatment could not eliminate it.Conclusion: In conclusion the best medium for sperm and DNA incubation was SPTALP.The DNA not only could attach to the post acrosomal region of spermatozoabut also could integrate into it. So bovine spermatozoa can be used as transgenecarrier into oocyte

Deferasirox, an Iron-Chelating Agent, Improves Testicular Morphometric and Sperm Functional Parameters in a Rat Model of Varicocele

Varicocele is characterized by testicular dysfunction that originates from hyperthermia and hypoxia, leading to defects in testicular tissue and altered spermatozoa structure and function. The varicocele testis is characterized by the presence of intracellular iron deposits that contribute to the associated oxidative stress. Therefore, we tested the hypothesis that administration of an iron-chelating agent, such as deferasirox (DFX), could potentially mitigate the consequences of varicocele on testicular tissue and spermatozoa. Using a well-established rat model of varicocele (VCL), we show that treatment with DFX partially improved the structure and function of the testis and spermatozoa. In particular, sperm motility was markedly restored whereas abnormal sperm morphology was only partially improved. No significant improvement in sperm count was observed that could be associated with the proapoptotic response observed following iron chelation treatment. No reduction in oxidative damage to spermatozoa was observed since lipid peroxidation and DNA integrity were not modified. This was suggested to be a result of increased oxidative stress. Finally, we also saw no indication of attenuation of the endoplasmic reticulum/unfolded protein (ER/UPR) stress response that we recently found associated with the VCL testis in rats