日本物理学会誌及びJournal of the Physical Society of Japanの月刊について

Adiabatic evolution along the instantaneous eigenstate of a time-dependent Hamiltonian is used for robust and high fidelity state transfer in atomic and molecular physics. Shortcuts to adiabaticity (STA) are systematic approaches to accomplish the same final state transfer in a faster manner. This article presents an introduction to STA and reviews different theoretical approaches and applications of STA to a range of scientific and engineering tasks in quantum physics and beyond.

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Shortcuts to adiabaticity: Concepts, methods, and applications

Molecular absorption and emission bands dominate the visible, infrared, and submillimeter spectra of most objects with associated gas. These observations reveal a surprisingly rich array of molecular species and attest to a complex chemistry taking place in the harsh environment of the interstellar medium of galaxies. Molecules are truly everywhere and an important component of interstellar gas. This review surveys molecular observations in the various spectral windows and summarizes the chemical and physical processes involved in the formation and evolution of interstellar molecules. The rich organic inventory of space reflects the multitude of chemical processes involved that, on the one hand, build up molecules an atom at a time and, on the other hand, break down large molecules injected by stars to smaller fragments. Both this bottom-up and the trickle-down chemistry are reviewed. The emphasis is on understanding the characteristics of complex polycyclic aromatic hydrocarbon molecules and fullerenes and their role in chemistry as well as the intricate interaction of gas-phase ion-molecule and neutral-neutral reactions and the chemistry taking place on grain surfaces in dense clouds in setting the organic inventory of regions of star and planet formation and their implications for the chemical history of the Solar System. Many aspects of molecular astrophysics are illustrated with recent observations of the HIFI instrument on the Herschel Space Observatory.

https://cab.inta-csic.es/molecular_universe_2011/pressroomNew/tielensInterview.pdf

The molecular universe

The tremendous interest in nanoscale structures such as quantum dots (zero-dimension) and wires (quasi-one-dimension) stems from their size-dependent properties. One-dimensional (1D) semiconductor nanostructures are of particular interest because of their potential applications in nanoscale electronic and optoelectronic devices. For 1D semiconductor nanomaterials to have wide practical application, however, several areas require further development. In particular, the fabrication of desired 1D nanomaterials with tailored atomic structures and their assembly into functional devices are still major challenges for nanotechnologists. In this review, we focus on the status of research on the formation of nanowire structures via highly anisotropic growth of nanocrystals of semiconductor and metal oxide materials with an emphasis on the structural characterization of the nucleation, initial growth, defects and interface structures, as well as on theoretical analyses of nanocrystal formation, reactivity and stability. We review various methods used and mechanisms involved to generate 1D nanostructures from different material systems through self-organized growth techniques including vapor–liquid–solid growth, oxide-assisted chemical vapor deposition (without a metal catalyst), laser ablation, thermal evaporation, metal-catalyzed molecular beam epitaxy, chemical beam epitaxy and hydrothermal reaction. 1D nanostructures grown by these technologies have been observed to exhibit unusual growth phenomena and unexpected properties, e.g., diameter-dependent and temperature-dependent growth directions, structural transformation by enhanced photothermal effects and phase transformation induced by the point contact reaction in ultra-thin semiconductor nanowires. Recent progress in controlling growth directions, defects, interface structures, structural transformation, contacts and hetero-junctions in 1D nanostructures is addressed. Also reviewed are the quantitative explorations and predictions of some challenging 1D nanostructures and descriptions of the growth mechanisms of 1D nanostructures, based on the energetic, dynamic and kinetic behaviors of the building block nanostructures and their surfaces and/or interfaces.

Growth of nanowires

Curved pi-conjugation, aromaticity, and the related chemistry of small fullerenes (< C60) and single-walled carbon nanotubes.

Ultracold single molecules have wide-ranging potential applications, such as ultracold chemistry, precision measurements, quantum simulation, and quantum computation. However, given the difficulty of achieving full control of a complex atom-molecule system, the coherent formation of single molecules remains a challenge. Here, we report an alternative route to coherently bind two atoms into a weakly bound molecule at megahertz levels by coupling atomic spins to their two-body relative motion in a strongly focused laser with inherent polarization gradients. The coherent nature is demonstrated by long-lived atom-molecule Rabi oscillations. We further manipulate the motional levels of the molecules and measure the binding energy precisely. This work opens the door to full control of all degrees of freedom in atom-molecule systems.

https://science.sciencemag.org/content/sci/early/2020/09/23/science.aba7468.full.pdf

Coherently forming a single molecule in an optical trap.

A supersaturation of nitrogen atoms is found in the surface layer of microstructured silicon after femtosecond (fs) laser irradiation in NF3. The average nitrogen concentration in the uppermost 50 nm is about 0.5 ± 0.2 at. %, several orders of magnitude higher than the solid solubility of nitrogen atoms in silicon. The nitrogen-hyperdoped silicon shows high crystallinity in the doped layer, which is due to the repairing effect of nitrogen on defects in silicon lattices. Nitrogen atoms and vacancies can be combined into thermal stable complexes after fs laser irradiation, which makes the nitrogen-hyperdoped silicon exhibit good thermal stability of optical properties.

A nitrogen-hyperdoped silicon material formed by femtosecond laser irradiation

A series of fundamental properties from atomic geometry, electronic band structure, optical absorption, to dynamics are systemically studied for the silicon doped with supersaturated chalcogens (S, Se, and Te). The atomic structures in a broad energy range are obtained and distinguished as three classes named the substitutional, interstitial, and quasi-substitutional. Their relative energies varying with the S, Se, and Te samples reveal that the concentration of impurity atoms occupying the substitutional position, which plays an important role in optical absorption, will be different and get progressively higher from S-, Se-, to Te-hyperdoped silicon. Electronic band structures show that for the most atomic geometries the defect-related states do appear into the gap of silicon, and the optical absorption calculations clarify that they are the very origin of the broadband absorption of chalcogen-hyperdoped silicon. Combining the optical absorption properties with the structural transformation from molecular-dynamics simulations, we disclose the micromechanism of annealing-induced reduction of infrared absorptance. Furthermore, we conclude that both the different concentrations of the substitutional doping and structural transformation will lead to the different annealing-induced reduction of infrared absorptance for S-, Se-, and Te-hyperdoped silicon as observed in experiments.

https://iopscience.iop.org/article/10.1209/0295-5075/99/46005/pdf

Physical mechanisms for the unique optical properties of chalcogen-hyperdoped silicon

Electricity-based response to NH3 of graphene oxide (GO) is demonstrated at ppm level at room temperature. The GO film prepared on planar silicon substrate shows weak response when exposed to 50 ppm NH3, response time less than 30 s and recovery time about 100 s. More interestingly, the GO film coated on laser-textured silicon substrate shows significant enhancement for sensor response, and meanwhile response/recovery time is mainly preserved. Furthermore, a good response of textured GO film is detected in a dynamic range of 5–100 ppm NH3. The surface morphology and chemical bonds of the textured GO film are studied by scanning electron microscope (SEM), Fourier Transform Infrared (FT-IR) Spectrometer and X-ray Photoelectron Spectrometer (XPS), respectively. The NH3 response is attributed to the polar oxygen configurations of GO and the enhanced response is due to the richer oxygen configurations that stem from cobwebby microstructure of GO.

/pdf/room-temperature-nh-3-sensing-of-graphene-oxide-film-and-its-rtrv1pjyz2.pdf

Jun Zhuang

Papers

Coherently forming a single molecule in an optical trap.

A nitrogen-hyperdoped silicon material formed by femtosecond laser irradiation

Physical mechanisms for the unique optical properties of chalcogen-hyperdoped silicon

Room-temperature NH 3 sensing of graphene oxide film and its enhanced response on the laser-textured silicon.

First-principles study of Ni/Ni3Al interface strengthening by alloying elements