Probing chirality with inelastic electron-light scattering

Probing molecular chirality via laser-induced electronic fluxes

Chirality is ubiquitous in nature and of fundamental importance in science. The present work focuses on understanding the conditions required to modify the chirality during ultrafast electronic motion by bringing enantiomers out-of-equilibrium. Different kinds of ultrashort linearly-polarised laser pulses are used to drive an ultrafast charge migration process by the excitation of a small number of low-lying excited states from the ground electronic state of S- and R-epoxypropane. Control over chiral electron dynamics is achieved by choosing the different orientations of the linearly polarised…

探测声子手性和环形晶格运动的对称性选择性非线性光学光谱

Probing phonon chirality and circular lattice motion with symmetry-selective nonlinear optical spectroscopy

研究通过对称性选择性太赫兹差频光谱探测声子手性和环形晶格运动，验证了手性声子的识别方法，揭示了环形离子运动与角动量的关系。

Probing Anomalous Inelastic Scattering in Spin-ice Ho$_2$Ti$_2$O$_7$ through Resonant Raman Spectroscopy

We report on a study of the inelastic scattering properties of (001) and (111) Ho$_2$Ti$_2$O$_7$ single crystals at room temperature. Structural and compositional analysis along with absorption measurement confirms single crystalline phase of all samples. Room temperature polarized Raman measurements were performed on crystals in non-resonant and two different resonant conditions by using six different laser excitation lines. Lorentzian model fitting analysis is performed on all measured spectra in order to identify the difference in the Raman scattering cross-section in resonant and non-reson…

Unscrambling Structured Chirality with Structured Light at Nanoscale Using Photo-induced Force

We introduce a microscopy technique that facilitates the prediction of spatial features of chirality of nanoscale samples by exploiting photo-induced optical force exerted on an achiral tip in the vicinity of the test specimen. The tip-sample interactive system is illuminated by structured light to probe both the transverse and longitudinal (with respect to the beam propagation direction) components of the sample magnetoelectric polarizability as the manifestation of its sense of handedness, i.e., chirality. We specifically prove that although circularly polarized waves are adequate to detect …

拓扑光学手性双折射

Topological Optical Chirality Dichroism

研究手性三维系统对光手性的拓扑双折射，揭示手性拓扑不变量导致整数量化的双折射激发率差异，并提出利用超手性光探测三维材料手性能带拓扑的实验方案。

莫尔材料中环流手性的光学涡旋探针

Optical vortex probe of loop-current chirality in moiré materials

提出利用光学涡旋束的轨道角动量差探测莫尔材料中本征环流手性的方法，以扭曲双层石墨烯为例，通过C3对称性选择的贝里曲率角谐波在非线性光电流中识别手性信号。

Weak Measurements of Light Chirality with a Plasmonic Slit

We examine, both experimentally and theoretically, an interaction of tightly focused polarized light with a slit on a metal surface supporting plasmon-polariton modes. Remarkably, this simple system can be highly sensitive to the polarization of the incident light and offers a perfect quantum-weak-measurement tool with a built-in post-selection in the plasmon-polariton mode. We observe the plasmonic spin Hall effect in both coordinate and momentum spaces which is interpreted as weak measurements of the helicity of light with real and imaginary weak values determined by the input polarization. …

通过多极手性光物质相互作用揭示轨道光学手性

Unveiling orbital optical chirality through multipolar chiral light-matter interaction

本研究证明光学手性可源于光的轨道角动量，通过金纳米二聚体和光学涡旋光束测量到由OAM驱动的四极矩手性响应，确立了超越偶极范式的轨道光学手性新形式。

Magnetoelectric Effects in Local Light-Matter Interactions

We study the generic interaction of a monochromatic electromagnetic field with bi-isotropic nanoparticles. Such an interaction is described by dipole-coupling terms associated with the breaking of dual, P- and T-symmetries, including the chirality and the nonreciprocal magnetoelectric effect. We calculate absorption rates, radiation forces, and radiation torques for the nanoparticles and introduce novel characteristics of the field quantifying the transfer of energy, momentum, and angular-momentum in these interactions. In particular, we put forward the concept of 'magnetoelectric energy densi…

方位角-径向偏振光束：螺旋度与动量密度、产生方式及最优手性光

The Azimuthally-Radially Polarized Beam: Helicity and Momentum Densities, Generation and Optimal Chiral Light

本研究探究方位角-径向偏振光束（ARPB）的光学特性，定义其最优手性光状态，推导场量与动量密度分布，提出可控生成方案，有望用于手性粒子的一维精准探测与对映体分离。

Probing vectorial near field of light: imaging theory and design principles of nanoprobes

Near-field microscopy is widely used for characterizing electromagnetic fields at nanoscale, where nanoprobes afford the opportunity to extract subwavelength optical quantities, including the amplitude, phase, polarization and chirality. However, owing to the complexity of various nanoprobes, a general and intuitive theory is highly needed to assess the vectorial field response of the nanoprobes and interpret the mechanism of the probe-field interaction. Here, we develop a general imaging theory based on the reciprocity of electromagnetism and multipole expansion analysis. The proposed theory …

Strong chiral dichroism in above threshold ionization and ionization rates from locally-chiral light

We derive here a new highly selective photoelectron-based chirality-sensing technique that utilizes 'locally-chiral' laser pulses. We show that this approach results in strong chiral discrimination, where the standard forwards/backwards asymmetry of photoelectron circular dichroism (PECD) is lifted. The resulting dichroism is much larger and more robust than conventional PECD, is found in all hemispheres, and is not symmetric or antisymmetric with respect to any symmetry operator. Remarkably, a CD of up to 10% survives in the angularly-integrated above-threshold ionization (ATI) spectra, and o…