Constructions of synthetic lattices in modulated ring resonators attract growing attentions for exploring interesting physics beyond the geometric dimensionality, where complicated conn

Constructions of synthetic lattices in modulated ring resonators attract growing attentions for exploring interesting physics beyond the geometric dimensionality, where complicated connectivities between resonant frequency modes are explored in many theoretical proposals. Here, we implement the experimental demonstration of generating the stub lattice along the frequency axis of light, realized in two coupled ring resonators of different lengths while the larger ring undergoing dynamic modulation. Such synthetic photonic structure naturally exhibits the physics of flat band. We show that the time-resolved band structure read out from the drop-port output of the excited ring is the intensity projection of the band structure onto specific resonant mode in the synthetic momentum space, where gapped flat band, mode localization effect, and flat to non-flat band transition are observed in experiments and verified by simulations. Our work gives a direct evidence for the constructing synthetic stub lattice using two different rings, which hence makes a solid step towards experimentally constructing more complicated lattices in multiple rings associated with synthetic frequency dimension.show less

Entanglement serves as a fundamental resource for quantum information protocols, and hyperentanglement has received an explosively increasing amount of attention for its high-capacity c

Entanglement serves as a fundamental resource for quantum information protocols, and hyperentanglement has received an explosively increasing amount of attention for its high-capacity characteristic. Increasing the scale of hyperentanglement, i.e., the number of modes in a hyperentangled system, is crucial for enhancing its capability in quantum information processing. Here we demonstrate the generation of large-scale continuous-variable (CV) hyperentanglement in three degrees of freedom (DOFs), including azimuthal and radial indexes of Laguerre-Gaussian (LG) modes and frequency. In our experiment, 216 pairs of hyperentangled modes are deterministically generated from the four-wave mixing process in an atomic vapor. Besides, we show that the entanglement between coherent LG superposition modes denoted by both azimuthal and radial quantum numbers can also be generated from this system. Such large-scale CV hyperentanglement in three DOFs presents an efficient scheme to significantly increase the information capacity of the CV system. Our results provide a new platform for studying CV quantum information and open the avenue for constructing high-capacity parallel and multiple-DOF CV quantum information protocols.show less

The temporal evolutions of electron density and plasma diameter of 1 kHz filament in air are investigated by utilizing a pump-probe longitudinal diffraction method. A model based on sca

The temporal evolutions of electron density and plasma diameter of 1 kHz filament in air are investigated by utilizing a pump-probe longitudinal diffraction method. A model based on scalar diffraction theory is proposed to extract the phase shift from the diffraction patterns. The hydrodynamic effect on plasma evolution at 1 kHz filament is included and analyzed. The measured initial peak electron density ~10^18 cm^-3 in our experimental conditions decays rapidly by nearly two orders of magnitude within 200 ps. Moreover, the plasma channel size rises from 90μm to 120μm as the delay time increases. The experimental observation is in agreement with numerical simulation results by solving the rate equations.show less

Snapshot spectral ghost imaging, which can acquire the dynamic spectral imaging information in the field of view, has attracted more attention in recent years. Studies have shown that o

Snapshot spectral ghost imaging, which can acquire the dynamic spectral imaging information in the field of view, has attracted more attention in recent years. Studies have shown that optimizing the fluctuation of light fields is essential to improve the sampling efficiency and the reconstruction quality of ghost imaging. However, the optimization of broadband light fields in snapshot spectral ghost imaging is challenging due to the dispersion of the modulation device. In the paper, by judiciously introducing a hybrid refraction/diffraction structure into the light field modulation, a snapshot spectral ghost imaging with broadband super-Rayleigh speckles was demonstrated. Simulation and experimental results verify that the contrast of speckles in a broad range of wavelengths has been significantly improved, and the imaging system has superior noise immunity.show less