NOON State Generation with Phonons in Acoustic Wave Resonators Assisted by a Nitrogen‐Vacancy‐Center Ensemble

Since the quality factor of an acoustic wave resonator (AWR) reached 10¹¹, AWRs have been regarded as a good carrier of quantum information. In this paper, a scheme to construct a NOON state with two AWRs assisted by a nitrogen‐vacancy‐center ensemble (NVE) is proposed. The two AWRs cross each other vertically, and the NVE is located at the center of the crossing. By considering the decoherence of the system and using resonant interactions between the AWRs and the NVE, and the single‐qubit operation of the NVE, a NOON state can be achieved with a fidelity higher than 98.8% when the number of phonons in the AWR is $N\le 3$.     

Ambient dependence of visible emissions in SrTiO3

We investigated the visible emission property of SrTiO₃ (STO) single crystals with high temperature annealing in some ambient conditions. We found that the green emission in STO, which should be associated with intermediate states originating from functional ionic defects inside the samples, such as cation/oxygen vacancies, showed strong ambient dependence. While high temperature annealing in the O₂ atmosphere suppressed the intensity of visible emission, annealing in an O₂-free atmosphere, such as N₂ or H₂, increased it. The broad visible emissions were fitted with three sub-modes, whose intensities showed different evolutions with respect to the ambient condition. Our study demonstrated the systematic development of defect states with the amount of the oxygen vacancies in STO.     

Thermodynamic aspects of carbon redistribution during ageing and tempering of Fe–Ni–C alloys

Carbon redistribution is known to occur during martensite ageing. The two associated processes most discussed in the literature are spinodal decomposition and carbon segregation to defects. In order to elucidate the topic, the ageing and tempering of two Fe–Ni–C alloys have been characterised by means of atom probe tomography and synchrotron radiation diffraction. Upon ageing at room temperature, carbon redistribution is clearly observed, where the process of carbon segregation to defects appears to be most likely to occur. Nevertheless, the possibility of spinodal decomposition is not entirely discarded, and the current work presents a series of discussion points that challenge our current understanding of the thermodynamic of ferrite in steels.     

The influence of radiation-induced vacancy on the formation of thin-film of compound layer during a reactive diffusion process

A theoretical approach is developed that describes the formation of a thin-film of AB-compound layer under the influence of radiation-induced vacancy. The AB-compound layer is formed as a result of a chemical reaction between the atomic species of A and B immiscible layers. The two layers are irradiated with a beam of energetic particles and this process leads to several vacant lattice sites creation in both layers due to the displacement of lattice atoms by irradiating particles. A- and B-atoms diffuse via these lattice sites by means of a vacancy mechanism in considerable amount to reaction interfaces A/AB and AB/B. The reaction interfaces increase in thickness as a result of chemical transformation between the diffusing species and surface atoms (near both layers). The compound layer formation occurs in two stages. The first stage begins as an interfacial reaction controlled process, and the second as a diffusion controlled process. The critical thickness and time are determined at a transition point between the two stages. The influence of radiation-induced vacancy on layer thickness, speed of growth, and reaction rate is investigated under irradiation within the framework of the model presented here. The result obtained shows that the layer thickness, speed of growth, and reaction rate increase strongly as the defect generation rate rises in the irradiated layers. It also shows the feasibility of producing a compound layer (especially in near-noble metal silicide considered in this study) at a temperature below their normal formation temperature under the influence of radiation.     

Vacancy-like defects in nanocrystalline SnO2: influence of the annealing treatment under different atmospheres

The study of electronic and chemical properties of semiconductor oxides is motivated by their several applications. In particular, tin oxide is widely used as a solid state gas sensor material. In this regard, the defect structure has been proposed to be crucial in determining the resulting film conductivity and then its sensitivity. Here, the characteristics of vacancy-like defects in nanocrystalline commercial high-purity tin oxide powders and the influence of the annealing treatment under different atmospheres are presented. Specifically, SnO₂ nanopowders were annealed at 330 °C under three different types of atmospheres: inert (vacuum), oxidative (oxygen) and reductive (hydrogen). The obtained experimental results are discussed in terms of the vacancy-like defects detected, shedding light to the basic conduction mechanisms, which are responsible for gas detection.     

堪为物理学第三分支的计算物理

本文是作者1982年在中国访问时所作的讲演,论述物理学各领域的前沿工作,用许多事例说明计算物理对推动物理理论的重大意义。文中还指出计算物理在其性质、方法及需要等方面不同于和独立于解析的理论物理和实验物理,而成为物理学的第三分支。     

Self-interstitial solute interaction in aluminium base alloys: Problems of data interpretation

The interpretation of electrical resistivity measurement results of Al base alloys is critically discussed. Correct numerical data evaluation with respect to the atomistic properties r_c/r_p, r_t and Pf^t/Pf is yet impossible for Al and its alloys because of the overlapping of Ic and Id recovery for those electron irradiations for which damage rate measurements exist and because of the unexplained scatter of initial damage rate data.