Generation of high-contrast and high-intensity laser pulses using an OPCPA preamplifier in a double CPA, Ti:sapphire laser system

We demonstrate a high-contrast, high-intensity double chirped-pulse amplification (CPA) Ti:sapphire laser system using an optical parametric chirped-pulse (OPCPA) pre- amplifier. By injecting cleaned microjoule seed pulses into the OPCPA, a temporal contrast greater than 10¹⁰ within picosecond times before the main femtosecond pulse is demonstrated with an output pulse energy of 1.7 J and a pulse duration of 30 fs, corresponding to a peak power of 60 TW at a 10 Hz repetition rate. This system uses a cryogenically-cooled Ti:sapphire final amplifier and generates focused peak intensities in excess of 10²⁰ W/cm².     

Synthetic studies on macroviracin A: a rapid construction of C(42) macrocyclic dilactone corresponding to the core

The C(2)-symmetric macrodiolide core 2 of an antiviral agent, macroviracin A (1), was constructed in a single step by the intermolecular macrodimerization of C(22)-hydroxy carboxylic acid 3 with 2-chloro-1,3-dimethylimidazolinium chloride and DMAP in the presence of sodium hydride (NaH). The use of potassium hydride instead of NaH caused the intramolecular cyclization, predominantly providing the corresponding monomer 26. The acid 3 was synthesized through a series of reactions such as the coupling reaction of acetylene 5 and oxirane 6, stereoselective glycosidation with the trichloroacetimidate method, and Jones oxidation.     

Intersection theory over quantum ruled surfaces

In this paper, we will extend several results on intersection theory over commutative ruled surfaces to quantum ruled surfaces. Typically, we define the fiber of a closed point, the quasi-section, and the quasi-canonical divisor on a quantum rules surface, and study how these “curves” on a quantum ruled surface intersect with each other.     

Quantitative agent-based firm dynamics simulation with parameters estimated by financial and transaction data analysis

Firm dynamics on a transaction network is considered from the standpoint of econophysics, agent-based simulations, and game theory. In this model, interacting firms rationally invest in a production facility to maximize net present value. We estimate parameters used in the model through empirical analysis of financial and transaction data. We propose two different methods (analytical method and regression method) to obtain an interaction matrix of firms. On a subset of a real transaction network, we simulate firm's revenue, cost, and fixed asset, which is the accumulated investment for the production facility. The simulation reproduces the quantitative behavior of past revenues and costs within a standard error when we use the interaction matrix estimated by the regression method, in which only transaction pairs are taken into account. Furthermore, the simulation qualitatively reproduces past data of fixed assets.     

Electronic band structure and Fermi surface of CaB6 studied by angle-resolved photoemission spectroscopy

We report high-resolution angle-resolved photoemission spectroscopy (ARPES) on CaB6. The band structure determined by ARPES shows a 1 eV energy gap at the X point between the valence and the conduction bands. We found a small electron pocket at the X point, whose carrier number is estimated to be (4-5) x 10(19) cm(-3), in good agreement with the Hall resistivity measurement with the same crystal. The experimental results are discussed in comparison with band structure calculations and theoretical models for the high-temperature ferromagnetism.     

Fermi surface topology of Ca1.5Sr0.5RuO4 determined by angle-resolved photoelectron spectroscopy

We report angle-resolved photoelectron spectroscopy results of the Fermi surface of Ca1.5Sr0.5RuO4, which is at the boundary of magnetic/orbital instability in the phase diagram of the Ca-substituted Sr ruthenates. Three t(2g) energy bands and the corresponding Fermi surface sheets are observed, which are also present in the Ca-free Sr2RuO4. We find that while the Fermi surface topology of the alpha,beta (d(yz,zx)) sheets remains almost the same in these two materials, the gamma (d(xy)) sheet exhibits a holelike Fermi surface in Ca1.5Sr0.5RuO4 in contrast to being electronlike in Sr2RuO4. Our observation of all three volume conserving Fermi surface sheets clearly demonstrates the absence of orbital-selective Mott transition, which was proposed theoretically to explain the unusual transport and magnetic properties in Ca1.5Sr0.5RuO4.     

Quantum theory of state reduction and measurement

The central problem in the quantum theory of measurement, how to describe the process of state reduction in terms of the quantum mechanical formalism, is solved on the basis of the relativity of quantal states, which implies that once the apparatus is detected in a well-defined state, the object state must reduce to a corresponding one. This is a process termed by Schrödinger disentanglement. Here, it is essential to observe that Renninger's negative result does constitute an actual measurement process. From this point of view, Heisenberg's interpretation of his microscope experiment and the Einstein-Podolsky-Rosen arguments are reinvestigated. Satisfactory discussions are given to various experimental situations, such as the Stern-Gerlach-type experiment, successive measurements, macroscopic measurements, and Schrödinger's cat. Finally it is proposed to regard a state vector in quantum mechanics as an irreducible physical construct, in Margenau's sense, that is not further analyzable both mathematically and conceptually.     

Analysis of the paramagnetic susceptibility of Fe(HCOO)2·2H2O

The paramagnetic susceptibility of powdered Fe(HCOO)₂·2H₂O is analysed by the combined method of high temperature expansion and molecular field approximation. The experimental data are well explained by the consistent model obtained in the previous specific heat analysis.     

Dynamics change of phoborhodopsin and transducer by activation: study using D75N mutant of the receptor by site-directed solid-state 13C NMR

Pharaonis phoborhodopsin (ppR or sensory rhodopsin II) is a negative phototaxis receptor of Natronomonas pharaonis, and forms a complex, which transmits the photosignal into cytoplasm, with its cognate transducer (pHtrII). We examined a possible local dynamics change of ppR and its D75N mutant complexed with pHtrII, using solid-state (13)C NMR of [3-(13)C]Ala- and [1-(13)C]Val-labeled preparations. We distinguished Ala C(beta) (13)C signals of relatively static stem (Ala221) in the C-terminus of the receptors from those of flexible tip (Ala228, 234, 236 and 238), utilizing a mutant with truncated C-terminus. The local fluctuation frequency at the C-terminal tip was appreciably decreased when ppR was bound to pHtrII, while it was increased when D75N, that mimics the signaling state because of disrupted salt bridge between C and G helices prerequisite for the signal transfer, was bound to pHtrII. This signal change may be considered with the larger dissociation constant of the complex between pHtrII and M-state of ppR. At the same time, it turned out that fluctuation frequency of cytoplasmic portion of pHtrII is lowered when ppR is replaced by D75N in the complex with pHtrII. This means that the C-terminal tip partly participates in binding with the linker region of pHtrII in the dark, but this portion might be released at the signaling state leading to mutual association of the two transducers in the cytoplasmic regions within the ppR/pHtrII complex.     

Quantum control of the hyperfine spin of a Cs atom ensemble

We demonstrate quantum control of a large spin angular momentum associated with the F=3 hyperfine ground state of 133Cs. Time-dependent magnetic fields and a static tensor light shift are used to implement near-optimal controls and map a fiducial state to a broad range of target states, with yields in the range 0.8-0.9. Squeezed states are produced also by an adiabatic scheme that is more robust against errors. Universal control facilitates the encoding and manipulation of qubits and qudits in atomic ground states and may lead to the improvement of some precision measurements.