Parallel generation of quadripartite cluster entanglement in the optical frequency comb

Scalability and coherence are two essential requirements for the experimental implementation of quantum information and quantum computing. Here, we report a breakthrough toward scalability: the simultaneous generation of a record 15 quadripartite entangled cluster states over 60 consecutive cavity modes (Q modes), in the optical frequency comb of a single optical parametric oscillator. The amount of observed entanglement was constant over the 60 Q modes, thereby proving the intrinsic scalability of this system. The number of observable Q modes was restricted by technical limitations, and we conservatively estimate the actual number of similar clusters to be at least 3 times larger. This result paves the way to the realization of large entangled states for scalable quantum information and quantum computing.     

Measurement of the neutron beam polarization of BL05/NOP beamline at J-PARC

We measured the neutron beam polarization of the BL05/NOP (Neutron Optics and Physics) beamline at J-PARC with an accuracy of less than 10⁻³ using polarized ³He gas as a neutron spin analyzer. Precise polarimetry of the neutron beam is necessary to understand the beamline optics as well as for the asymmetry measurements of the neutron beta decay, which are planned in this beamline.     

Determination of 36Cl in environmental samples collected in the JCO by AMS

Long-lived chlorine, ³⁶Cl (T_1/2 = 301,000 y) in environmental samples has been measured by the AMS system installed in Tandem Accelerator Center, University of Tsukuba. A tri-carbon-molecular ¹²C₃ ^- pilot beam method is used to stabilize the terminal voltage of the tandem. A small amount of pure carbon graphite is well mixed into a AgCl target material for creating Cl^- and ¹²C₃ ^- in the ion source. A ³⁶S isobaric interference in the system is eliminated to determine ³⁶Cl in environmental samples by chemical procedure. Some samples containing chlorine such as soil, chemical reagents and table salt have been collected in the JCO criticality accident site and analyzed to detect neutron-induced ³⁶Cl. The experimental result has been compared with a theoretical calculation.     

Incorporating Mathematics into the Science Program of Students Labeled “At‐Risk”

Twenty three at‐risk high school female students who had failed mathematics and science in a traditional school setting were the subjects of this study that integrated mathematics and science lessons over a period of four weeks. Using a combination of direct instruction, calculations, graphing, hands‐on projects, and discussion, the topic of mechanical advantage was studied, to find out how well students understood the topic. The study found that these students who initially knew very little about mechanical advantage, and who did not see any need to use mathematics in the study of science, indicated an increased understanding of mechanical advantage, and also seemed to realize that integrating mathematics and science enhanced learning.     

Radiative melting of a horizontal clear ice layer

In this paper the horizontal layer of clear ice sticking to the substrate is melted by comparatively short wave radiation similar to solar radiation for the purpose of removing ice from the surface of the material subject to atmospheric icing. The radiating source used for melting is 300 wattages halogen lamps whose color temperature is 3200K at 100 voltages. From the present investigation, a typical phenomenon of backmelting is observed clearly and it can be found that the predicted results including the melting rate of upper and lower layers which are melted by radiant energy impinged on or penetrated the ice layer are in good agreement with the experimental results.

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Aufschmelzen einer waagerechten Klareisschicht durch Strahlung

Zusammenfassung Eine waagerechte Klareisschicht, die auf einer Unterlage aufgefroren war, wurde durch kurzwellige Strahlung, Ähnlich der Sonnenstrahlung, zum Schmelzen gebracht, um die Entfernung von Eis nach atmosphÄrischer Vereisung zu untersuchen. Die Strahlungsquelle war eine 300 Watt-Halogenlampe mit einer Farbtemperatur von 3200 Kelvin bei 100 Volt. Als typische Erscheinung wurde ein Rückseiten-Schmelzen gefunden, im übrigen sind die vorausberechneten Schmelzraten an der Ober- und der Unterseite durch aufgenommene oder durchgelassene Strahlungsenergie in guter übereinstimmung mit den Messungen.

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Nomenclature a_v monochromatic absorption coefficient - A transmission (= q _r ⁺ {h_i}/q_ro) - c_p specific heat - E_bv monochromatic emissive power - h_D mass transfer coefficient - h_i initial thickness of ice layer - h_m thickness of substrate - L_i latent heat of melting - L_w latent heat of evaporation or condensation - heat flux absorbed at surface of substrate - q_r0 radiant heat flux impinged onto ice or free surface - q _r ⁺ {y} forward radiant heat flux - q _r ^– {y} backward radiant heat flux - S₁ thickness of upper melt layer - S₂ thickness of lower melt layer - S'₂ distance from free surface to bottom surface of ice layer - t time - T temperature - T₁ temperature of air-water or air-ice interface - T₂ temperature of substrate surface - T₃ temperature of back side surface of substrate - T_b temperature of radiating source - T_i temperature in ice layer - T_w1 temperature in upper melt layer - T_w2 temperature in lower melt layer - T environmental temperature - W_w saturated vapor concentration at free surface - W_t8 vapor concentration at environment - y distance from free or ice surface - y grid size of water or ice - y_m grid size of substrate Greek symbols heat transfer coefficient - spectral absorptivity - _t total absorptivity - _i thermal diffusivity of ice - _m thermal diffusivity of substrate - _w thermal diffusivity of water - _i thermal conductivity of ice - _m thermal conductivity of substrate - _w thermal conductivity of water - wavelength - _av densitiy of air-vapor mixture - _i density of ice - Stefan-Boltzman constant     

Radiative melting of ice layer adhering to a vertical surface

This paper is concerned with melting of a vertical ice layer adhering to the substrate by using radiating heat source of halogen lamps having a large fraction of short wave beam or nichrome heater having a comparatively large fraction of long wave one. From the present experimental results, it can be seen that the heating of short wave radiation produces a peculiar melting behavior of strongly rough melting-surface due to the internal melting at the grain boundary of ice-surface. On the other hand, for the case of long wave radiation the melting-surface becomes very smooth. The melting rate of clear ice layer by short wave radiation obtained from halogen lamps is smaller than that of cloudy ice layer due to the good penetration of short wave fraction through the clear ice layer. Moreover, the raising of temperature of ice-substrate interface could offer a feasibility of removing ice layer from the structure subject to atmospheric icing. Concludingly, it is clarified that the melting rate of ice layer could be predicted numerically by using the band model of extinction coefficient or absorption coefficient presented in this study.

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Schmelzen einer Eisschicht an einer senkrechten Wand durch Strahlung

Zusammenfassung Diese Arbeit behandelt das Schmelzen einer senkrechten Eisschicht auf einer Unterlage mit Hilfe von Halogen-Lampen mit einem hohen Anteil an kurzen Wellen und Nichromheizern mit einem hohen Anteil an langen Wellen. Aus diesen Versuchen läßt sich ableiten, daß die Heizung durch kurzwellige Strahlung ein eigentümliches Schmelzverhalten mit sehr rauher Oberfläche hervorruft, verursacht durch Schmelzen an den Korngrenzen der Eisoberfläche. Bei langwelliger Heizung wird die Oberfläche sehr glatt. Die Abschmelzrate einer Klareisschicht bei kurzwelliger Heizung durch Halogen-Lampen ist geringer als die einer Opaleisschicht wegen des besseren Eindringens der kurzen Wellen in das klare Eis. Der Temperaturanstieg an der Grenze Eis — Unterlage bietet die Möglichkeit der Enteisung von Bauteilen, die der atmosphärischen Vereisung ausgesetzt sind. Es folgt, daß die Abschmelzrate einer Eisschicht, numerisch vorausberechnet werden kann, indem man das Bandmodell des Extinktions- und des Absorptionskoeffizienten dieser Arbeit verwendet.

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Nomenclature A transmission, defined in equation (4) - a monochromatic absorption coefficient of clear ice - C constant - E_b monochromatic emissive power - h_i thickness of ice layer - h_in initial thickness of ice layer - h_m thickness of substrate - k₀ extinction coefficient for h₀ 0 - k_s modified extinction coefficient - k monochromatic extinction coefficient - L_i latent heat of melting - n index number, defined in equation (2) - heat flux absorbed at surface of substrate - q_r0 radiant heat flux impinged onto ices-urface - q_ri{y} radiant heat flux in ice layer - S distance from initial ice-surface to transient melting-surface - T_b temperature of radiating heat source - T_i temperature in ice layer - T_m temperature in substrate - T environmental temperature - T₁ temperature of surface of ice layer - T₂ temperature of substrate-surface - T₃ temperature of back side surface of substrate - t time - y distance from initial ice-surface - Z ratio of backward radiative heat flux to forward one for cloudy ice Greek Symbols heat transfer coefficient - _i thermal diffusivity of ice - _m thermal diffusivity of substrate - _i thermal conductivity of ice - _m thermal conductivity of substrate - wavelength - _c critical wavelength - _i density of ice - Stefan-Boltzmann constant     

Freezing limit of water in a closed circular tube

This paper is concerned with the freezing of water in a closed metal tube by regarding the effect of volumetric change of water which is closely related with solidification. The pressure of unfrozen water in the tube increases gradually with increasing frozen layer, consequently the freezing temperature of the water decreases monotonically. It is found from the present results that the freezing limit of water corresponding to the cease of freezing caused by no temperature difference between environmental temperature and freezing point would exist. This remarkable phenomena are mainly attributed to the combined effect of environmental temperature and inner diameter of the tube.     

A Triphenylamine with Two Phenoxy Radicals Having Unusual Bonding Patterns and a Closed‐Shell Electronic State

Reported herein is the structure and the electronic properties of a novel triphenylamine derivative having two phenoxy radicals appended to the amino nitrogen atom. X‐ray single crystal analysis and the magnetic resonance measurements demonstrates the unexpected closed‐shell electronic structure, even at room temperature, of the molecule and two unusual C? N bonds with multiple‐bond character. The theoretical calculations support the experimentally determined molecular geometry with the closed‐shell electronic structure, and predicted a small HOMO–LUMO gap originating from the nonbonding character of the HOMO. The optical and electrochemical measurements show that the molecule has a remarkably small HOMO–LUMO gap compared with its triphenylamine precursor.