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two photon

Hélène Fleurbaey, Sandrine Galtier, Simon Thomas, Marie Bonnaud, Lucile Julien, François Biraben, François Nez, Michel Abgrall, Jocelyne Guéna
We present a new measurement of the 1S-3S two-photon transition frequency of hydrogen, realized with a continuous-wave excitation laser at 205 nm on a room-temperature atomic beam, with a relative uncertainty of 9×10^{-13}. The proton charge radius deduced from this measurement, r_{p}=0.877(13)  fm, is in very good agreement with the current CODATA-recommended value. This result contributes to the ongoing search to solve the proton charge radius puzzle, which arose from a discrepancy between the CODATA value and a more precise determination of r_{p} from muonic hydrogen spectroscopy...
May 4, 2018: Physical Review Letters
Xiao-Min Hu, Bi-Heng Liu, Yu Guo, Guo-Yong Xiang, Yun-Feng Huang, Chuan-Feng Li, Guang-Can Guo, Matthias Kleinmann, Tamás Vértesi, Adán Cabello
We present the first experimental confirmation of the quantum-mechanical prediction of stronger-than-binary correlations. These are correlations that cannot be explained under the assumption that the occurrence of a particular outcome of an n≥3-outcome measurement is due to a two-step process in which, in the first step, some classical mechanism precludes n-2 of the outcomes and, in the second step, a binary measurement generates the outcome. Our experiment uses pairs of photonic qutrits distributed between two laboratories, where randomly chosen three-outcome measurements are performed...
May 4, 2018: Physical Review Letters
F Yoshihara, T Fuse, Z Ao, S Ashhab, K Kakuyanagi, S Saito, T Aoki, K Koshino, K Semba
We report on experimentally measured light shifts of superconducting flux qubits deep-strongly coupled to LC oscillators, where the coupling constants are comparable to the qubit and oscillator resonance frequencies. By using two-tone spectroscopy, the energies of the six lowest levels of each circuit are determined. We find huge Lamb shifts that exceed 90% of the bare qubit frequencies and inversions of the qubits' ground and excited states when there are a finite number of photons in the oscillator. Our experimental results agree with theoretical predictions based on the quantum Rabi model...
May 4, 2018: Physical Review Letters
Debarghya Sarkar, Wei Wang, Matthew Mecklenburg, Andrew J Clough, Matthew Yeung, Chenhao Ren, Qingfeng Lin, Louis Blankemeier, Shanyuan Niu, Huan Zhao, Haotian Shi, Han Wang, Stephen B Cronin, Jayakanth Ravichandran, Mitul Luhar, Rehan Kapadia
The growth of crystalline compound semiconductors on amorphous and non-epitaxial substrates is a fundamental challenge for state-of-the-art thin-film epitaxial growth techniques. Direct growth of materials on technologically relevant amorphous surfaces, such as nitrides or oxides results in nanocrystalline thin-films, or nanowire type structures, preventing growth and integration of high-performance devices and circuits on these surfaces. Here we show crystalline compound semiconductors grown directly on technologically relevant amorphous and non-epitaxial substrates in geometries compatible with standard microfabrication technology...
May 18, 2018: ACS Nano
Xiaoli Huang, Qiyang Li, Xue Xiao, Shuping Jia, Yue Li, Zhigang Duan, Lei Bai, Ze Yuan, Lin Li, Zhihua Lin, Yonggang Zhao
We present here the synthesis of one enantiomeric pair of metal-organic framework materials comprised of a unique multioriented double-helix structure from an achiral spirocenter ligand. Our study clearly shows that the chiral MOF material encompasses concurrently multiple nonlinear-optical functions in the solid state: the noncentrosymmetric structural feature brings the chiral MOF high second-harmonic-generation efficiency; the incorporation of the spirocenter ligand can efficiently produce two-photon-excited photoluminescence with a larger-action cross-sectional value...
May 18, 2018: Inorganic Chemistry
Felix Schell, Andrey E Boguslavskiy, Claus Peter Schulz, Serguei Patchkovskii, Marc J J Vrakking, Albert Stolow, Jochen Mikosch
We study the Strong-Field Ionization (SFI) of the hydrocarbon 1-butene as a function of wavelength using photoion-photoelectron covariance and coincidence spectroscopy. We observe a striking transition in the fragment-associated photoelectron spectra: from a single Above Threshold Ionization (ATI) progression for photon energies less than the cation D0-D1 gap to two ATI progressions for a photon energy greater than this gap. For the first case, electronically excited cations are created by SFI populating the ground cationic state D0, followed by sequential post-ionization excitation...
May 18, 2018: Physical Chemistry Chemical Physics: PCCP
Kohei Yoshihara, Tsuyoshi Matsuda, Yuta Kohro, Hidetoshi Tozaki-Saitoh, Kazuhide Inoue, Makoto Tsuda
The role of astrocytes in the spinal dorsal horn (SDH) for sensory information processing under normal conditions is poorly understood. In this study, we investigated whether SDH astrocytes respond to noxious and innocuous stimuli to the skin of normal mice using in vivo two-photon Ca2+ imaging under anesthesia. We found that noxious stimulation evoked by intraplantar formalin injection provoked an elevation in intracellular Ca2+ levels in SDH astrocytes. By contrast, neither instantaneous noxious pinching nor innocuous stimuli (cooling or brushing) to the hindpaw elicited astrocytic Ca2+ responses...
May 3, 2018: Journal of Pharmacological Sciences
Yoshiki Ishizawa, Suguru Dobashi, Noriyuki Kadoya, Kengo Ito, Takahito Chiba, Yoshiki Takayama, Kiyokazu Sato, Ken Takeda
PURPOSE: An accurate source model of a medical linear accelerator is essential for Monte Carlo (MC) dose calculations. This study aims to propose an analytical photon source model based on particle transport in parameterized accelerator structures, focusing on a more realistic determination of linac photon spectra compared to existing approaches. METHODS: We designed the primary and secondary photon sources based on the photons attenuated and scattered by a parameterized flattening filter...
May 17, 2018: Medical Physics
Lina Li, Xiaoying Shang, Sasa Wang, Ningning Dong, Chengmin Ji, Xueyuan Chen, Sangen Zhao, Jun Wang, Zhihua Sun, Maochun Hong, Junhua Luo
Perovskite ferroelectrics with prominent nonlinear optical absorption have attracted great attention in the field of photonics. However, they are traditionally dominated by inorganic oxides and exhibit relatively small nonlinear optical absorption coefficients which hinder their further applications. Herein, we report a new organic-inorganic hybrid bilayered perovskite ferroelectric, (C4H9NH3)2(NH2CHNH2)Pb2Br7 (1), showing an above-room-temperature Curie temperature (~322 K) and notable spontaneous polarization (~3...
May 17, 2018: Journal of the American Chemical Society
Lotte Hahn Enevoldsen, Marie Tindborg, Nichlas Lindegaard Hovmand, Christina Christoffersen, Helga Ellingsgaard, Charlotte Suetta, Bente Merete Stallknecht, Poul Joergen Jennum, Andreas Kjær, Steen Gammeltoft
Study objectives: To investigate the activity of brown adipose tissue (BAT) in type 1 narcolepsy patients during cold exposure using two separate scans of sympathetic and metabolic activity of BAT in order to evaluate whether orexin deficiency leads to altered non-shivering thermoregulation in narcolepsy. Methods: Seven patients with type 1 narcolepsy and seven healthy controls underwent two consecutive scans after 2 h cold exposure: 123I-meta-iodo-benzyl-guanidine (123I-MIBG) single photon emission computed tomography and 18F-2-deoxy-glucose (18F-FDG) positron emission tomography and computed tomography to visualize sympathetic innervation and metabolic activity of BAT, respectively...
May 15, 2018: Sleep
John Biggins, Sadegh Yazdi, Emilie Ringe
Nanoparticles of some metals (Cu/Ag/Au) sustain oscillations of their electron cloud called localized surface plasmon resonances (LSPRs). These resonances can occur at optical frequencies and be driven by light, generating enhanced electric fields and spectacular photon scattering. However, current plasmonic metals are rare, expensive, and have a limited resonant frequency range. Recently, much attention has been focused on earth-abundant Al, but Al nanoparticles cannot resonate in the IR. The earth-abundant Mg nanoparticles reported here surmount this limitation...
May 17, 2018: Nano Letters
Sourav Sahoo, Sucheta Mondal, Gwilym Williams, Andrew May, Sam Ladak, Anjan Barman
Three-dimensional magnetic nanostructures are now attracting intense interest due to their potential as ultrahigh density future magnetic storage devices. Here, we report on the study of ultrafast magnetization dynamics of a complex three-dimensional magnetic nanostructure. Arrays of magnetic tetrapod structures were fabricated using a combination of two-photon lithography (TPL) and electrodeposition. All-optical time-resolved magneto-optical Kerr microscopy was exploited to probe the spin-wave modes from the junction of a single tetrapod structure...
May 17, 2018: Nanoscale
Avshalom C Elitzur, Eliahu Cohen, Ryo Okamoto, Shigeki Takeuchi
Since its publication, Aharonov and Vaidman's three-box paradox has undergone three major advances: i). A non-counterfactual scheme by the same authors in 2003 with strong rather than weak measurements for verifying the particle's subtle presence in two boxes. ii) A realization of the latter by Okamoto and Takeuchi in 2016. iii) A dynamic version by Aharonov et al. in 2017, with disappearance and reappearance of the particle. We now combine these advances together. Using photonic quantum routers the particle acts like a quantum "shutter...
May 16, 2018: Scientific Reports
Feng Wang, Erik Bélanger, Sylvain L Côté, Patrick Desrosiers, Steven A Prescott, Daniel C Côté, Yves De Koninck
Primary afferents transduce environmental stimuli into electrical activity that is transmitted centrally to be decoded into corresponding sensations. However, it remains unknown how afferent populations encode different somatosensory inputs. To address this, we performed two-photon Ca2+ imaging from thousands of dorsal root ganglion (DRG) neurons in anesthetized mice while applying mechanical and thermal stimuli to hind paws. We found that approximately half of all neurons are polymodal and that heat and cold are encoded very differently...
May 15, 2018: Cell Reports
Genggongwo Shi, Taeseung Yoon, Seoncheol Cha, Seulgi Kim, Muhammad Yousuf, Nisar Ahmed, Doseok Kim, Hyun-Wook Kang, Kwang S Kim
Water-soluble, carbazole-based two-photon excitable fluorescent probes MPVC-I ("turn-on") and MPVC-II ("turn-off") are rationally designed and synthesized for the selective monitoring of carbon monoxide (CO). Both probes can effectively measure carboxyhemoglobin (HbCO) in the blood of the animals exposed to a CO dose as low as 100 ppm for 10 min. The palladium catalyzed azidocarbonylation reaction was optimized to improve the sensing efficiency.
May 16, 2018: ACS Sensors
Kenneth Squire, Xianming Kong, Paul LeDuff, Gregory L Rorrer, Alan X Wang
Fluorescence biosensing is one of the most established biosensing methods, particularly fluorescence spectroscopy and microscopy. These are two highly sensitive techniques but require high grade electronics and optics to achieve the desired sensitivity. Efforts have been made to implement these methods using consumer grade electronics and simple optical setups for applications such as point-of-care diagnostics, but the sensitivity inherently suffers. Sensing substrates, capable of enhancing fluorescence are thus needed to achieve high sensitivity for such applications...
May 16, 2018: Journal of Biophotonics
Hui Cai, Bin Chen, Mark Blei, Shery L Y Chang, Kedi Wu, Houlong Zhuang, Sefaattin Tongay
Akin to the enormous number of discoveries made through traditional semiconductor alloys, alloying selected 2D semiconductors enables engineering of their electronic structure for a wide range of new applications. 2D alloys have been demonstrated when two components crystallized in the same phase, and their bandgaps displayed predictable monotonic variation. By stabilizing previously unobserved compositions and phases of GaSe1-x Te x at nanoscales on GaAs(111), we demonstrate abnormal band bowing effects and phase instability region when components crystallize in different phases...
May 15, 2018: Nature Communications
Minhaeng Cho
Parametric down-conversion is a second-order nonlinear optical process annihilating a pump photon and creating a pair of photons in the signal and idler modes. Then, by using two parametric down-converters and introducing a path indistinguishability for the two generated idler modes, a quantum coherence between two conjugate signal beams can be induced. Such a double spontaneous or stimulated parametric down-conversion scheme has been used to demonstrate quantum spectroscopy and imaging with undetected idler photons via measuring one-photon interference between their correlated signal beams...
May 14, 2018: Journal of Chemical Physics
Xiaopeng Wang, Xingyu Liu, Cameron Cook, Bohdan Schatschneider, Noa Marom
Singlet fission (SF), the spontaneous down-conversion of a singlet exciton into two triplet excitons residing on neighboring molecules, is a promising route to improve organic photovoltaic (OPV) device efficiencies by harvesting two charge carriers from one photon. However, only a few materials have been discovered that exhibit intermolecular SF in the solid state, most of which are acene derivatives. Recently, there has been a growing interest in rylenes as potential SF materials. We use many-body perturbation theory in the GW approximation and the Bethe-Salpeter equation to investigate the possibility of intermolecular SF in crystalline perylene and quaterrylene...
May 14, 2018: Journal of Chemical Physics
Jesús Daniel Valenzuela-Sau, Raúl García-Llamas
We calculated the out-of-plane band structure of a two-dimensional dispersive photonic crystal (PC). To achieve this goal, the plane wave expansion method was implemented in conjunction with a numerical algorithm, the dispersive photonic crystal iterative method. The PC is an array of circular cross-sectional dispersive MgO Lorentz single-pole rods in a square lattice. The frequency bands are calculated starting at Γ as a function of the oblique component of the wave vector. For the lowest frequencies, it was found that the modes bend drastically to the horizon as the dielectric constant ϵ(ω) is increased to a very positive value...
May 15, 2018: Optics Letters
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