Strong-laser-field physics, non-classical light states and quantum information science.

Strong-laser-field physics is a research direction that relies on the use of high-power lasers and has led to fascinating achievements ranging from relativistic particle acceleration to attosecond science. On the other hand, quantum optics has been built on the use of low photon number sources and has opened the way for groundbreaking discoveries in quantum technology, advancing investigations ranging from fundamental tests of quantum theory to quantum information processing. Despite the tremendous progress, until recently these directions have remained disconnected. This is because the majority of the interactions in the strong-field limit have been successfully described by semi-classical approximations treating the electromagnetic field classically, as there was no need to include the quantum properties of the field to explain the observations. The link between strong-laser-field physics, quantum optics, and quantum information science has been developed in the recent past. Studies based on fully quantized and conditioning approaches have shown that intense laser-matter interactions can be used for the generation of controllable entangled and non-classical light states. These achievements open the way for a vast number of investigations stemming from the symbiosis of strong-laser-field physics, quantum optics, and quantum information science. Here, after an introduction to the fundamentals of these research directions, we report on the recent progress in the fully quantized description of intense laser-matter interaction and the methods that have been developed for the generation of non-classical light states and entangled states. Also, we discuss the future directions of non-classical light engineering using strong laser fields, and the potential applications in ultrafast and quantum information science.

Extended Bose-Hubbard model with dipolar excitons.

The Hubbard model constitutes one of the most celebrated theoretical frameworks of condensed-matter physics. It describes strongly correlated phases of interacting quantum particles confined in lattice potentials1,2. For bosons, the Hubbard Hamiltonian has been deeply scrutinized for short-range on-site interactions3-6. However, accessing longer-range couplings has remained elusive experimentally7. This marks the frontier towards the extended Bose-Hubbard Hamiltonian, which enables insulating ordered phases at fractional lattice fillings8-12. Here we implement this Hamiltonian by confining semiconductor dipolar excitons in an artificial two-dimensional square lattice. Strong dipolar repulsions between nearest-neighbour lattice sites then stabilize an insulating state at half filling. This characteristic feature of the extended Bose-Hubbard model exhibits the signatures theoretically expected for a chequerboard spatial order. Our work thus highlights that dipolar excitons enable controlled implementations of boson-like arrays with strong off-site interactions, in lattices with programmable geometries and more than 100 sites.

Beta-carotene prolongs survival, decreases lipid peroxidation and enhances glutathione status in transplantable murine lymphoma.

Carotenoids of dietary origin have recently been the subject of renewed research interest because of epidemiological evidence indicating an inverse relationship between intake of carotenoids-rich plant substances and risk of certain cancers. This study was attempted to understand the biological actions of dietary beta-carotene (BC) on Dalton's lymphoma (DL), a rapidly proliferating transplantable tumor, in effecting the survival of the lymphoma-bearing mice. The glutathione (GSH) level and the extent of lipid peroxidation in the liver, kidney and brain were monitored in BC-treated (100 mg/kg food) mice transplanted with DL. These markers showed substantial alterations during the whole length of tumor progression in lymphoma-bearing mice without BC supplementation. When treated with BC, both malondialdehyde contents (evidence of lipid peroxidation) and the GSH levels in different organs were found to be closer to normal values in the initial period of tumor progression. BC-mediated protection against lipid peroxidation was maximally found to be in hepatic tissue throughout the study following DL transplantation. This was fairly reflected in the higher BC concentration in hepatic tissue of BC-treated lymphoma group compared to untreated lymphoma control. Significantly higher survival time (51-55 days) was observed in BC-treated animals in comparison to their untreated DL counterparts (35-38 days). The prolonged survival observed in the BC-supplemented animals may be attributed to the higher resistance offered by animals receiving BC towards lipid peroxidation-related tissue injury.

Construction of infectious SIV/HIV-2 chimeras.

OBJECTIVE: To construct SIV/HIV-2 chimeras (SHIV) that replicate in vivo. These would be valuable tools to elucidate the mechanism by which HIV-2 can bypass protection conferred by live attenuated SIV vaccines. METHOD: Novel SHIV were constructed to express either the vpx, vpr, tat, rev and env genes (SHIV-2isy env) or the gag and pol genes (SHIV-2isy gag/pol) of the infectious molecular clone HIV-2isy in an SIVmac backbone. The replication of SHIV-2isy env and SHIV-2isy gag/pol were evaluated on selected cell lines and peripheral blood mononuclear cells (PBMC) in vitro. In addition, their infectivity was assessed in vivo. RESULT: Virus stocks of SHIV-2isy env and SHIV-2isy gag/pol were prepared in vitro. For SHIV-2isy gag/pol both the 5' and 3' boundaries of the chimeric construct were critical for infectivity in vitro. The growth of each chimera on T cell lines in vitro mirrors that of the parental viruses donating the envelope gene. On PBMCs SHIV-2isy env replicated well on human and simian PBMC whereas SHIV-2isy gag/pol replicated to detectable levels on human PBMC only. In vivo, SHIV-2isy env virus was isolated from one of two cynomolgus macaques challenged intravenously, SHIV-2isy gag/pol was isolated from one of two cynomolgus macaques and both rhesus macaques challenged intravenously. CONCLUSION: This is the first report of SIV/HIV-2 chimeras that are infectious in macaques. Moreover, this is the first report of an infectious chimera in which both SIV gag and pol have been replaced with the equivalent regions of an HIV isolate.

Effect of different fractions of methanolic extract of the seeds of Dolichos biflorus on some microorganisms.

Extracts from different parts of plants (1) including seeds are reported to act upon pathogenic microorganisms. A few active principles were isolated. The present preliminary report shows significant role of the seeds of Dolichos biflorus (Linn), locally known as Kulthi, against some test organisms using different fractions of defatted seed extracts with methanol.

Purification and characterisation of a non-specific lipid transfer protein from goat liver.

A non-specific lipid transfer protein has been purified from the pH 5.1 supernatant of goat liver by DEAE-cellulose, CM-cellulose and Sephadex G-75 column chromatography. The protein shows a single band on polyacrylamide gel electrophoresis and transfers 450 nmol of phosphatidylcholine per min per mg of protein under the present assay condition. This protein has a subunit molecular weight of 12,000 and an isoelectric point of 8.65. Amino acid analysis reveals the absence of methionine. Histidine has been identified as the only N-terminal amino acid. Besides phosphatidylcholine, the protein transfers phosphatidylinositol, phosphatidylethanolamine, phosphatidylserine and cholesterol. Chemical modification studies showed the involvement of free amino and thiol groups in the maintenance of the transfer activity of the goat liver protein.