Quantum system identification

The aim of quantum system identification is to estimate the ingredients inside a black box, in which some quantum-mechanical unitary process takes place, by just looking at its input-output behavior. Here we establish a basic and general framework for quantum system identification, that allows us to classify how much knowledge about the quantum system is attainable, in principle, from a given experimental setup. We show that controllable closed quantum systems can be estimated up to unitary conjugation. Prior knowledge on some elements of the black box helps the system identification. We present an example in which a Bell measurement is more efficient to identify the system. When the topology of the system is known, the framework enables us to establish a general criterion for the estimability of the coupling constants in its Hamiltonian.     

Mechanistic understanding of multistep assembly of DNA with a carbazole ligand by simple adjustment of host-guest concentrations

Two alternative binding states are identified in interaction of calf thymus DNA with a partially hydrophobic carbazole ligand [(Im(+))(2)Cz], where biphasic UV-vis and circular dichroic (CD) spectral changes are apparent during the titration of calf thymus DNA with the carbazole ligand.     

Universally measure-preserving homeomorphisms of cantor minimal systems

In 1995, T. Giordano, I. Putnam, and C. Skau [GPS] made a significant breakthrough in Cantor minimal system theory. They completely classified Cantor minimal systems in the sense of topological orbit equivalence by using C*-algebra and homological algebra techniques. Since then, a dynamical proof of their theorem has been conjectured. Such a proof is presented in this paper. We establish orbit equivalence theory based on a finite coordinate change relation arising from an ordered Bratteli diagram, which is known from [HK] in the finitary case of ergodic probability measure-preserving transformations. We obtain the Orbital Extension Theorem. This theorem is considered a topological version of the Copying Lemma of Y. Katznelson and B. Weiss [KW], which has played an important role in measured orbit equivalence theory.     

Gold(I)-catalyzed asymmetric synthesis of planar chiral arene chromium complexes

Gold(I)-catalyzed asymmetric cyclization of 1,3-dihydroxymethyl-2-alkynylbenzene chromium complexes gave planar chiral isochromene chromium complexes with high enantioselectivity. Enantiomeric excess of the cyclization products was largely affected by a combination of axially chiral diphosphine(AuCl)(2) precatalysts and silver salts. A system of segphos(AuCl)(2) with AgBF(4) resulted in the formation of the corresponding antipode.     

Convolution reconstruction algorithm for refraction-contrast computed tomography using a Laue-case analyzer for dark-field imaging

We derive a reconstruction algorithm for refraction-contrast computed tomography (CT) using dark-field imaging (DFI) optics, which can extract refraction information by a single shot, from the ray equation in geometrical optics. The proposed algorithm is similar to the convolution reconstruction technique widely used in conventional CT. Thus, this algorithm can be implemented simply while also being fast and stable. To demonstrate its validity, we constructed the imaging system based on DFI optics composed of a transmission Laue-type angular analyzer at the vertical wiggler beamline BL-14C in KEK and performed a preliminary imaging experiment using a physical phantom to successfully obtain the DFI-CT image using the proposed algorithm.     

MBE growth of a novel chalcopyrite-type ternary compound MnGeP2

Novel ternary Mn-containing compound MnGeP₂ has been grown on GaAs and InP substrates using molecular beam epitaxy, in which Mn and Ge were supplied from solid sources and P from a gas source. The films obtained showed XRD pattern characteristic of MnGeP₂. Lattice constants were determined using reciprocal lattice mapping analysis. Films directly grown on GaAs substrate showed three-dimensional grain-growth. By introduction of a Ge buffer layer growth mode became two-dimensional. The magnetization vs. temperature curve showed ferromagnetic properties at room temperature, in conflict with theory which predicts its antiferromagnetism. Presence of secondary phase is discussed.     

Invariant measures for the subshifts arising from non-primitive substitutions

Every almost primitive substitution gives rise to an almost minimal subshift. The nonatomic, invariant measures of the subshift which are finite on every clopen set disjoint from a unique fixed point are unique up to scaling and ergodic.     

Two Distinct Thermal Stabilities of DNA and Enzymatic Activities of DNase I in a Multistep Assembly with Carbazole Ligands: Different Binding Characteristics for Duplex and Quadruplex DNA

A partially hydrophobic carbazole ligand ((Im⁺)₂Cz: 2,2′‐(9‐ethyl‐9 H‐carbazole‐3,6‐diyl)bis(ethyne‐2,1‐diyl)bis(1,3‐dimethyl‐1 H‐imidazol‐3‐ium)) adopts two different binding states (binding states I and II) in its interactions with calf‐thymus (ct‐) DNA. Two distinct binding states were identified by biphasic UV/Vis and circular dichroism (CD) spectral changes during the titration of DNA into the carbazole ligand. At low concentrations of ct‐DNA, (Im⁺)₂Cz binds to nearly every part of ct‐DNA (binding state I). By contrast, an increased concentration of ct‐DNA results in a switch in the DNA‐binding state, so that the ligands are bound per five DNA base pairs. Similarly, a monocationic carbazole ligand (Im⁺Cz: 2‐((6‐bromo‐9‐ethyl‐9 H‐carbazol‐3‐yl)ethynyl)‐1,3‐dimethyl‐1 H‐imidazol‐3‐ium) also shows biphasic UV/Vis spectral changes during the titration of ct‐DNA into Im⁺Cz, which suggests two different binding states of the Im⁺Cz ligand with ct‐DNA. The stepwise equilibrium of the ligand–DNA‐complex formation is capable of switching the thermal stability of ct‐DNA, as well as the enzymatic activity of deoxyribonuclease (DNase I). In binding state I, the (Im⁺)₂Cz ligands interact with nearly every base pair in ct‐DNA and stabilize the double‐helix structure, which results in a larger increase in the melting temperature of the ct‐DNA than that observed with binding state II. On the other hand, the (Im⁺)₂Cz ligand significantly reduces the enzymatic activity of DNase I in binding state I, although the enzymatic activity is recovered once the binding state of the ligand–DNA complex is changed to binding state II. The (Im⁺)₂Cz ligand was also employed as a binder for G‐quadruplex DNA. In contrast to the stepwise complex formation between (Im⁺)₂Cz and ct‐DNA, (Im⁺)₂Cz shows a monotonous UV/Vis spectral response during the titration of G‐quadruplex DNA into (Im⁺)₂Cz, which suggests a single binding state for (Im⁺)₂Cz with G‐quadruplex DNA.     

Fusibility of Poly(N-carboxy α-Amino Acid Anhydride) Materials Treated under Pressure-Heat Conditions and in Vitro-in Vivo Degradation of Hot-Pressed Materials

Powdered poly(N-carboxy α-amino acid anhydride) materials were treated at temperatures of 50, 100, 150, and 200°C under a pressure of 150 kg/cm². A number of hot-pressed materials showed simultaneous fusion and contraction in volume. The fusion temperature of the hot-pressed materials was generally lower than the true melting point of the powdered materials at atmospheric pressure (determined with a Differential Scanning Calorimeter). The hot-pressed materials had high rigidity and transparency. The in vitro-in vivo degradation of hot-pressed materials was also investigated. The homo- and copoly(α-amino acid) materials used in this study were scarcely degraded, though debenzylated t e rpolymers such as β-benzyl-L-aspartate/aspartic acid/L-leucine and γ -benzyl-L- glutamate/glutamic acid/L - leucine we re significantly degraded in both the in vitro and in vivo experiments. It was found that the in vivo degradation profile of hot-pressed terpolymer materials corresponds relatively well to degradation with 0.01% trypsin.