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Generation of single entangled photon-phonon pairs via an atom-photon-phonon interaction
摘要： Antibunching and entanglement play important roles in quantum information processing as antibunching is an essential ingredient for the production of single photons (phonons) and entanglement is a crucial resource for quantum communication and metrology. In this paper, we propose a atom-photon-phonon (tripartite) interaction in a hybrid cavity-atom-mechanics system, and show that both photon and phonon antibunching can be observed simultaneously under the resonant atomic driving. More importantly, the generated single photons and phonons are strongly correlated and entangled with each other, i.e., single entangled photon-phonon pairs are generated via the atom-photon-phonon interaction. The generation of single entangled photon-phonon pairs is the first step to implement entanglement-based quantum state transfer, which is essential for connecting mechanical and optical systems to build hybrid quantum networks.
关键词： antibunching,entanglement,atom-photon-phonon interaction,quantum information processing,hybrid cavity-atom-mechanics system
更新于2025-09-12 10:27:22
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Polarized monolithic white semipolar (20–21) InGaN light-emitting diodes grown on high quality (20–21) GaN/sapphire templates and its application to visible light communication
摘要： We demonstrate efficient, polarized and monolithic white semipolar (20–21) InGaN light-emitting diodes (LEDs) grown on high crystal quality 4-inch (20–21) GaN/sapphire template. Materials growth by metal-organic chemical vapor deposition (MOCVD) and characterization by atom probe tomography (APT) were carried out. The fabricated regular 0.1 mm2 size LEDs show a high electrical performance with an output power of 3.9 mW at 100 mA, an emission spectrum with two peaks located at 445 nm and 565 nm, a CIE point of (0.37, 0.42) and a polarization ratio of 0.30, which make them promising candidates for backlighting in liquid crystal displays (LCDs) application. Moreover, the fabricated square phosphor-free white μLED with size ranging from 20 to 60 μm, exhibit a high 3 dB modulation bandwidth of 660 MHz in the visible light communication (VLC) system, which benefits from the shorter carrier lifetime grown on the semipolar (20–21) plane. To our best knowledge, this is the first demonstration of monolithic white semipolar μLEDs in the VLC application, which can overcome the limitation of the slow frequency response of yellow phosphors converted commercial white LEDs. These results demonstrate the huge potentials to produce high efficiency monolithic white semipolar InGaN LEDs on cost-effective large area sapphire substrates.
关键词： Polarization,Light-emitting diodes,Atom probe tomography,Semipolar GaN,Visible light communication
更新于2025-09-12 10:27:22
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Discrete exited states influence on the harmonics spectrum generated in two-colour laser fields
摘要： The contribution of excited discrete atomic levels to the generation of high- and low-order harmonics in the interaction of a single atom with a two-color laser field has been studied for the first time. The studies were carried out for two types of atoms with different symmetry of the ground state wave functions (Ag, Ne) and for a two-color laser field consisting of the linearly polarized fundamental and second harmonics of Ti:Sa laser (ω + 2ω). The angle between the polarization of the ω + 2ω laser field components is varied. A significant effect of the symmetry of populated excited levels on the polarization characteristics of the generated harmonics is shown. A new method of control over the polarization state of the generated radiation is proposed.
关键词： non-perturbative theory,high harmonics generation,single atom response
更新于2025-09-12 10:27:22
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Surface Carbon Shell-Functionalized ZrO2 as Nanofiller in Polymer Gel Electrolyte-Based Dye-Sensitized Solar Cells
摘要： We prepare dye-sensitized solar cells (DSSCs) fabricated with a poly (ethylene glycol) based polymer gel electrolytes (PGEs) incorporating surface carbon shell-functionalized ZrO2 nanoparticles (ZrO2-C) as nano?llers (NFs). ZrO2 are polymerized via atom transfer radical polymerization (ATRP) using poly (ethylene glycol) methyl ether methacrylate (POEM) as a sca?old to prepare the ZrO2-C through carbonization. The power conversion e?ciency of DSSC with 12 wt% ZrO2-C/PGEs is 5.6%, exceeding that with PGEs (4.4%). The enhanced e?ciency is attributed to Lewis acid-base interactions of ZrO2-C and poly (ethylene glycol), catalytic e?ect of the carbon shells of ZrO2-C, which results in reduced crystallinity, enhanced ion conductivity of electrolytes, decreased counterelectrode/electrolyte interfacial resistance, and improved charge transfer rate. These results demonstrate that ZrO2-C introduction to PGEs e?ectively improves the performance of DSSCs.
关键词： polymer gel electrolyte (PGE),zirconium dioxide (ZrO2),dye-sensitized solar cell (DSSC),nano?ller (NF),carbon,atom transfer radical polymerization (ATRP)
更新于2025-09-12 10:27:22
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Metal-free and photo-controlled fabrication of fluorinated anti-fouling film
摘要： We reported a new photo-controlled synthesis route to fabricate a fluorine-containing thin film for protecting the oxidation of indium tin oxide (ITO) and other derivatives such as the fluorine-doped tin oxide (FTO) coated glasses. A relatively inexpensive, color/metal-free organic phenothiazine-based photocatalyst for atom transfer radical polymerization (ATRP) was successfully adopted by an ultraviolet light source to modified substrates. The fluorine thin film had a contact angle (CA) with water of 105.1°, an advancing angle of 112.2°, and a receding angle of 84.6°; leading to a hydrophobic nature with self-cleaning and anti-fouling properties. Our fluorinated conductive glass shows an optical transmittance up to 80 – 90% in the visible wavelength range. This work demonstrates the great value in the anti-fouling of electronics that secures itself from chemical contaminations in outdoor environments and use at high temperature and chemical erosions.
关键词： Atom Transfer Radical Polymerization (ATRP),ITO,Photo-controlled,Polymer brushes,FTO
更新于2025-09-12 10:27:22
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Laser drilling of micro-holes in single crystal silicon, indium phosphide and indium antimonide using a continuous wave (CW) 1070 nm fibre laser with millisecond pulse widths
摘要： The laser micro-drilling of “thru” holes, also known as via holes, in Si, InP and InSb semiconductor wafers was studied using millisecond pulse lengths from an IPG Laser Model YLR-2000 CW multimode 2 kW Ytterbium Fibre Laser and a JK400 (400 W) fibre laser, both with 1070 nm wavelength. The flexibility of this laser wavelength and simple pulsing scheme were demonstrated for semiconductor substrates of narrow (InSb Eg 0.17 eV) and wide (InP Eg 1.35 eV)) room-temperature bandgap, Eg, with respect to the photon energy of 1.1 eV. Optical microscopy and cross-sectional analysis were used to quantify hole dimensions and the distribution of recast material for all wafers and, for silicon, any microcracking for both (100) and (111) single crystal surface Si wafer orientations. It was found that the thermal diffusivity was not a sufficient parameter for predicting the relative hole sizes for the Si, InP and InSb single crystal semiconductors studied. Detailed observations for Si showed that, between the threshold energies for surface melting and the irradiance for drilling a “thru” hole from the front surface to rear surface, there was a range of irradiances for which micro-cracking occurred near the hole circumference. The directionality and lengths of these microcracks were studied for the (100) and (111) orientations and possible mechanisms for formation were discussed, including the Griffith criterion for microcracks and the failure mechanism of fatigue usually applied to welding of metals. For Si, above the irradiance for formation of a thru-hole, few cracks were observed. Future work will compare similar observations and measurements in other narrow- and wide-bandgap semiconductor wafer substrates. We demonstrated one application of this laser micro-drilling process for the micro-fabrication of a thru hole precisely-located in the centre of a silicon-based atom chip which had been patterned using semiconductor lithographic techniques. The end-user application was a source of magneto-optically trapped (MOT) cold atoms of Rubidium (87Rb) for portable quantum sensing.
关键词： microcrack,InP,Si,Griffith criterion,pulse,atom chip,Ytterbium fibre laser,semiconductor material,Fibre laser,semiconductor wafer,laser drilling,silicon,magneto-optical trap,MOT,via hole,laser micro-drilling,cold atoms,InSb,thru hole
更新于2025-09-12 10:27:22
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Atomic-scale quantitative analysis of implanted Mg in annealed GaN layers on free-standing GaN substrates
摘要： Achieving efficient p-type conduction in Mg-implanted GaN depends largely on postimplantation annealing conditions. Here, we study the effect of postimplantation annealing on the evolution of defects and their interactions with implanted Mg ions by using scanning transmission electron microscopy and atom probe tomography. We found that Mg clusters start to form by annealing the implanted sample above 1000 °C. In addition to the Mg clusters, stacking faults form at an annealing temperature of 1300 °C. The Mg concentrations of about 2–3 orders of magnitude higher than implanted Mg were segregated at the stacking faults. Nanobeam electron diffraction analysis revealed no distinct phase other than GaN formed at the Mg-enriched defects, suggesting that Mg is substituted for Ga in the GaN lattice at the edge of the stacking faults.
关键词： stacking faults,Mg clusters,postimplantation annealing,scanning transmission electron microscopy,Mg-implanted GaN,atom probe tomography
更新于2025-09-12 10:27:22
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[IEEE 2019 Antenna Measurement Techniques Association Symposium (AMTA) - San Diego, CA, USA (2019.10.6-2019.10.11)] 2019 Antenna Measurement Techniques Association Symposium (AMTA) - Waveguide-integrated Rydberg Atom-based RF Field Detector for Near-field Antenna Measurements
摘要： We demonstrate simultaneous amplitude and phase measurements of a radio-frequency (RF) ?eld through the use of a Rydberg atom-based sensor embedded inside a waveguiding structure. This measurement uses the Rydberg atom-based sensor in a mixer con?guration, which requires the presence of a local oscillator (LO) RF ?eld. The waveguiding structure supplies the LO ?eld. The combined waveguide and Rydberg atom system is used to measure phase and amplitude in the near-?eld of a horn antenna to extract the far-?eld pattern.
关键词： far-field pattern,near-field antenna measurements,waveguide,Rydberg atom-based sensor,RF field measurements
更新于2025-09-12 10:27:22
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Atom beam emersion from hot cavity laser ion sources
摘要： Ion sources exploiting laser resonance ionization offer efficient and element-selective radioactive ion beam production at the leading isotope separation on-line facilities worldwide. Most commonly, laser resonance ionization takes place inside a resistively heated atomizer tube directly coupled to the production target, where the element of interest is evaporated and provided as atomic vapor. While naturally the majority of atoms is ionized inside this hot cavity, a fraction of the neutrals effuses towards the high voltage beam extraction system of the subsequent mass separator. We report on several systematic investigations on this phenomenon regarding its significance and implications on the operation of resonance ionization laser ion sources. Experiments suggest a less sharply directed atom cone than expected from theoretical model, up to a lateral opening angle of 45°. Inside the tubular volume defined by the laser beam diameter around the central axis behind the source exit, more than 90% of potentially ionizable atoms are found within the first 2 cm. Geometrical constraints for the construction of devices based on ionization in the effusing atom beam directly downstream of the hot cavity are derived, and causes for cross-mass beam contamination are identified. Counter measures using laser repetition rate synchronized beam gating by fast electrostatic beam deflection to overcome these problems are presented.
关键词： Laser ion source,ISOLDE,Mass separation,Resonance laser ionization,Atom effusion,Ion source development
更新于2025-09-12 10:27:22
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Single-Atomically Anchored Cobalt on Carbon Quantum Dots as Efficient Photocatalysts for Visible Light-promoted Oxidation Reactions
摘要： Generation of efficient light-induced charge separation inside the photocatalyst is an essential factor for a high catalytic efficiency. The usual immobilization of metal or metal oxide particles on semiconductor photocatalysts offers an uncontrolled assembly of active sites during the reaction. The introduction of single metal atoms on photocatalysts can lead to extremely high atomic utilization and precise active sites. However, this approach is limited due to the lack of suitable photosensitizers for single atom immobilization. Here, we have designed photocatalytic carbon quantum dots with anchoring sites for single cobalt atoms in a defined Co-N4 structure via facile pyrolysis of vitamin B12. Carbon dots functioned as both light-harvesting antenna and support for cobalt atom with high atom loadings up to 3.27 wt.%. This new photocatalytic material demonstrated enhanced visible light absorption, efficient charge separation, and reduced electrochemical impedance, while the single Co atoms acted as the active site with strong oxidative ability. As a result, the photocatalysts showed excellent visible light-promoted photocatalytic efficiency with oxygen evolution rates up to 168 μmol h-1 g-1 via water oxidation, imine formation with high conversion (~90%) and selectivity (>99%), and complete photodegradation of organic dyes.
关键词： single-atom catalysts,oxidation reactions,carbon quantum dots,photocatalysis,visible light
更新于2025-09-12 10:27:22