分类： 光学 >> 量子光学 提交时间： 2023-02-19
摘要： We propose a method for enantio-detection of chiral molecules based on a cavity-molecule system, where the left- and right-handed molecules are coupled with a cavity and two classical light fields to form cyclic three-level models. Via the cavity-assisted three-photon processes based on the cyclic three-level model, photons are generated continuously in the cavity even in the absence of external driving to the cavity. However, the photonic fields generated from the three-photon processes of left- and right-handed molecules differ with the phase difference {\pi} according to the inherent properties of electric-dipole transition moments of enantiomers. This provides a potential way to detect the enantiomeric excess of chiral mixture by monitoring the output field of the cavity.
分类： 光学 >> 量子光学 提交时间： 2023-02-19
摘要： We propose an enantio-detection method of chiral molecules in a cavity with external drive. The chiral molecules are coupled with a quantized cavity field and two classical light fields to form the cyclic three-level systems. The chirality-dependent cavity-assisted three-photon process in the three-level systems leads to the generation of intracavity photons. Simultaneously, the drive field also results in the chirality-independent process of the generation of intracavity photons. Based on the interference between the intracavity photons generated from these two processes, one can detect the enantiomeric excess of chiral mixture via monitoring the transmission rate of the drive field.
分类： 天文学 >> 天文学 提交时间： 2023-02-19
摘要： A series of dynamical anomalies in the orbits of distant trans-Neptunian objects points to a new celestial body (usually named Planet Nine) in the solar system. In this draft, we point out that a mirror planet captured from the outer solar system or formed in the solar system is also a possible candidate. The introduction of the mirror matter model is due to an unbroken parity symmetry and is a potential explanation for dark matter. This mirror planet has null or fainter electromagnetic counterparts with a smaller optical radius and might be explored through gravitational effects.
分类： 天文学 >> 天文学 提交时间： 2023-02-19
摘要： A series of dynamical anomalies in the orbits of distant trans-Neptunian objects points to a new celestial body (usually named Planet Nine) in the solar system. In this draft, we point out that a mirror planet captured from the outer solar system or formed in the solar system is also a possible candidate. The introduction of the mirror matter model is due to an unbroken parity symmetry and is a potential explanation for dark matter. This mirror planet has null or fainter electromagnetic counterparts with a smaller optical radius and might be explored through gravitational effects.
分类： 天文学 >> 天文学 提交时间： 2023-02-19
摘要： High-resolution observations of the Perseus B5 "core" have previously revealed that this subsonic region actually consists of several filaments that are likely in the process of forming a quadruple stellar system. Since subsonic filaments are thought to be produced at the $\sim 0.1$ pc sonic scale by turbulent compression, a detailed kinematic study is crucial to test such a scenario in the context of core and star formation. Here we present a detailed kinematic follow-up study of the B5 filaments at a 0.009 pc resolution using the VLA and GBT combined observations fitted with multi-component spectral models. Using precisely identified filament spines, we find a remarkable resemblance between the averaged width profiles of each filament and Plummer-like functions, with filaments possessing FWHM widths of $\sim 0.03$ pc. The velocity dispersion profiles of the filaments also show decreasing trends towards the filament spines. Moreover, the velocity gradient field in B5 appears to be locally well ordered ($\sim 0.04$ pc) but globally complex, with kinematic behaviors suggestive of inhomogeneous turbulent accretion onto filaments and longitudinal flows towards a local overdensity along one of the filaments.
分类： 核科学技术 >> 粒子加速器 提交时间： 2025-03-10
摘要： As a fourth-generation synchrotron radiation light source working at 1.5 GeV, Wuhan Advanced Light Source (WALS) is being designed, which uses a full-energy linear accelerator (LINAC) as its electron beam injector. The injection beamline adopts a three-stage scheme: firstly, the beam from the LINAC that is 6 m under the storage ring is horizontally deflected below the storage ring, then it gradually climbs from underground to the same altitude as the storage ring, and finally the beam is delivered horizontally into the injection straight section inside the storage ring. Meanwhile, the Twiss parameter matching between the LINAC and storage ring is completed. During the construction of the beamline, magnet manufacturing errors, installation errors and beam injection errors from the LINAC will cause beam deviations from predetermined ideal orbits, and even particle losses. As a result, the electron beam correction is required during beam commissioning. Different from the single-direction beam correction of general transfer lines, the horizontal and vertical directions of the beam are coupled in the WALS injection transfer line, which greatly increases the complexity and difficulty of beam correction. Machine learning technology has been developed extensively in recent years, and its powerful algorithm of invertible neural network model is expected to be able to solve the beam commissioning difficulty of the beam injection transfer line at the WALS. Therefore, an invertible neural network model has been designed and trained to simulate the beam transport and beam correction of the WALS injection beamline. By optimizing the number and location of beam profile diagnostics, the accuracy of bidirectional prediction and beam correction effect can be greatly improved. The method is of great practical significance for the commissioning and operation of similar complex beam transport systems.
分类： 光学 >> 量子光学 提交时间： 2023-02-19
摘要： The transportation of photons and phonons typically obeys the principle of reciprocity. Breaking reciprocity of these bosonic excitations will enable the corresponding non-reciprocal devices, such as isolators and circulators. Here, we use two optical modes and two mechanical modes in a microresonator to form a four-mode plaquette via radiation pressure force. The phase-controlled non-reciprocal routing between any two modes with completely different frequencies is demonstrated, including the routing of phonon to phonon (MHz to MHz), photon to phonon (THz to MHz), and especially photon to photon with frequency difference of around 80 THz for the first time. In addition, one more mechanical mode is introduced to this plaquette to realize a phononic circulator in such single microresonator. The non-reciprocity is derived from interference between multi-mode transfer processes involving optomechanical interactions in an optomechanical resonator. It not only demonstrates the non-reciprocal routing of photons and phonons in a single resonator but also realizes the non-reciprocal frequency conversion for photons and circulation for phonons, laying a foundation for studying directional routing and thermal management in an optomechanical hybrid network.
分类： 光学 >> 量子光学 提交时间： 2023-02-19
摘要： The textbook-accepted formulation of electromagnetic force was proposed by Lorentz in the 19th century, but its validity has been challenged due to incompatibility with the special relativity and momentum conservation. The Einstein-Laub formulation, which can reconcile those conflicts, was suggested as an alternative to the Lorentz formulation. However, intense debates on the exact force are still going on due to lack of experimental evidence. Here, we report the first experimental investigation of angular symmetry of optical force inside a solid dielectric, aiming to distinguish the two formulations. The experiments surprisingly show that the optical force exerted by a Gaussian beam has components with the angular mode number of both 2 and 0, which cannot be explained solely by the Lorentz or the Einstein-Laub formulation. Instead, we found a modified Helmholtz theory by combining the Lorentz force with additional electrostrictive force could explain our experimental results. Our results represent a fundamental leap forward in determining the correct force formulation, and will update the working principles of many applications involving electromagnetic forces.
分类： 物理学 >> 核物理学 分类： 物理学 >> 交叉学科物理及相关领域的科学与技术 提交时间： 2024-08-09
摘要： Scanning magnets are devices responsible for deflecting particles to specific locations in particle therapy utilizing spot scanning techniques. To ensure the distortion of the scanned beams’ shapes remains within an acceptable level, it is necessary to guarantee that the homogeneity of the field integrals is sufficiently high in the two transversal directions within the good field region. Typically, this is accomplished by adding shims on both sides of magnet poles. In this study, we innovatively proposed a method to perform multi-objective optimization of shim parameters and excitation currents by the state-of-the-art evolutionary algorithm Non- dominated Sorting Genetic Algorithm-III (NSGA-III). Furthermore computer vision (CV) was implemented to automatically evaluate both the beam shape distortions and the centroids of the scanned beam spots at the target plane to assist efficient optimization process. With this method, optimal parameters of scanning magnets which have capability of scanning a carbon beam of 400 MeV/u beam energy across a 20 cm × 20 cm field size with a source-to-axis distance of 255 cm were obtained successfully. Meanwhile, we also conducted eddy current and temperature rise analysis, laminated steel plates with 19 slits cut near the pole gaps were used to reduce eddycurrents due to rapid variation of magnetic fields during the scanning process. Based on the optimized magnetsparameters, eddy current and temperature analyses were performed and the temperature rises were found to be near 40°C and 54°C for the Y and X magnets respectively at the designed scanning speeds, which meets the requirements for normal operation. This proposed procedure of optimization is expected to facilitate efficient and sophisticated design of various magnets applied to charged particle accelerators.
分类： 天文学 >> 天文学 提交时间： 2023-02-19
Simon E. T. Smith
Rachel Friesen
Antoine Marchal
Jaime E. Pineda
Paola Caselli
Michael Chun-Yuan Chen
Spandan Choudhury
James Di Francesco
Adam Ginsburg
Helen Kirk
Chris Matzner
Anna Punanova
Samantha Scibelli
Yancy Shirley
摘要： Filamentary structures have been found nearly ubiquitously in molecular clouds and yet their formation and evolution is still poorly understood. We examine a segment of Taurus Molecular Cloud 1 (TMC-1) that appears as a single, narrow filament in continuum emission from dust. We use the Regularized Optimization for Hyper-Spectral Analysis (ROHSA), a Gaussian decomposition algorithm which enforces spatial coherence when fitting multiple velocity components simultaneously over a data cube. We analyze HC$_5$N (9-8) line emission as part of the Green Bank Ammonia Survey (GAS) and identify three velocity-coherent components with ROHSA. The two brightest components extend the length of the filament, while the third component is fainter and clumpier. The brightest component has a prominent transverse velocity gradient of $2.7 \pm 0.1$ km s$^{-1}$ pc$^{-1}$ that we show to be indicative of gravitationally induced inflow. In the second component, we identify regularly spaced emission peaks along its length. We show that the local minima between pairs of adjacent HC$_5$N peaks line up closely with submillimetre continuum emission peaks, which we argue is evidence for fragmentation along the spine of TMC-1. While coherent velocity components have been described as separate physical structures in other star-forming filaments, we argue that the two bright components identified in HC$_5$N emission in TMC-1 are tracing two layers in one filament: a lower density outer layer whose material is flowing under gravity towards the higher density inner layer of the filament.
分类： 天文学 >> 天文学 提交时间： 2023-02-19
Mehrnoosh Tahani
Pierre Bastien
Ray S. Furuya
Kate Pattle
Doug Johnstone
Doris Arzoumanian
Yasuo Doi
Tetsuo Hasegawa
Shu-ichiro Inutsuka
Simon Coudé
Laura Fissel
Michael Chun-Yuan Chen
Frédérick Poidevin
Sarah Sadavoy
Rachel Friesen
Patrick M. Koch
James Di Francesco
Gerald H. Moriarty-Schieven
Zhiwei Chen
Eun Jung Chung
摘要： We study the HII regions associated with the NGC 6334 molecular cloud observed in the sub-millimeter and taken as part of the B-fields In STar-forming Region Observations (BISTRO) Survey. In particular, we investigate the polarization patterns and magnetic field morphologies associated with these HII regions. Through polarization pattern and pressure calculation analyses, several of these bubbles indicate that the gas and magnetic field lines have been pushed away from the bubble, toward an almost tangential (to the bubble) magnetic field morphology. In the densest part of NGC 6334, where the magnetic field morphology is similar to an hourglass, the polarization observations do not exhibit observable impact from HII regions. We detect two nested radial polarization patterns in a bubble to the south of NGC 6334 that correspond to the previously observed bipolar structure in this bubble. Finally, using the results of this study, we present steps (incorporating computer vision; circular Hough Transform) that can be used in future studies to identify bubbles that have physically impacted magnetic field lines.
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