Antiferromagnetic long-range order in dissipative Rydberg lattices

We study the dynamics of dissipative spin lattices with power-law interactions, realized via few-level atoms driven by coherent laser-coupling and decoherence processes. Using Monte-Carlo simulations, we determine the phase diagram in the steady state and analyze the dynamics of its generation. As opposed to mean-field predictions and nearest-neighbour models there is no phase transition to long-range ordered phases for realistic interactions and resonant driving. However, for finite laser detunings, we demonstrate the emergence of crystalline order with a vanishing dissipative gap. Although the found steady states differ considerably from those of an equilibrium Ising magnet, the critical exponent of the revealed dissipative phase transition falls into the 2D Ising universality class. Two complementary schemes for an experimental implementation with cold Rydberg atoms are discussed

Heterologous Expression of BchP, a Rhodobacter capsulatus Polypeptide Necessary for the Reductive Maturation of Bacteriochlorophyll agg to Bacteriochlorophyll ap

Photosynthetic bacteria contain bacteriochlorophyll (BChl) which has two major portions, a magnesium tetrapyrrole and an esterifying alcohol. BChl plays a key role in photosynthesis which is necessary for converting radiant energy into energy that can be used in cellular processes. The esterifying alcohol portion affects the function of the BChl in photosynthesis, but its role is not well understood. Rhodobacter capsulatus typically produces BChl a esyrtified with phytol (BChl ap), but site directed mutational analysis has shown that a mutation is bchP results in the accumulation of a BChl a esterified with geranylgeraniol (BChl agg) indicating that the product of the bchP locus (the BchP polypeptide) is necessary for the reductive maturation of BChl agg to BChl ap. In order to determine if BchP is sufficient for this process, the gene has been amplified using polymerase chain reaction and restriction endonuclease sites have been created flanking the gene so that it can be cloned into a plasmid known as pT7-7. This construct was then transformed into a strain of E. coli (C600) which contains the pGPl-2 plasmid with the gene for T7 RNA polymerase which is under the control of the APL promoter. When the strain containing both plasmids is incubated at 42°C. T7 RNA polymerase is produced which can transcribe bchP producing BchP. Future work will include in vitro assays to determine if BchP is sufficient for the maturation of BChl agg to BChl ap

Low-cost,stand-off, 2D+3D face imaging for biometric identification using Fourier transform profilometry –Update

Lockheed Martin Coherent Technologies is developing laser-based technologies for stand-off 2D+3D face imaging for biometric identification. Among other potential industrial, commercial, and governmental users, the Department of Homeland Security (DHS) and the Department of Defense (DoD) desire the ability to capture biometric data from minimally cooperative subjects with a minimally invasive system at stand-off distances. The initial applications are fixed installations for relatively large volume access points such as security check points and transportation gateways for which minimal cooperation, stand-off operation, and real-time operation are desired so that the biometric identification process will have little impact on traffic flow. Last year we presented a paper on the development and testing of a 2D+3D face imager breadboard based on th