Manipulating the Spatial Structure of Second-Order Quantum Coherence Using Entangled Photons

High-order quantum coherence reveals the statistical correlation of quantum particles. Manipulation of quantum coherence of light in the temporal domain enables the production of the single-photon source, which has become one of the most important quantum resources. High-order quantum coherence in the spatial domain plays a crucial role in a variety of applications, such as quantum imaging, holography, and microscopy. However, the active control of second-order spatial quantum coherence remains a challenging task. Here we predict theoretically and demonstrate experimentally the first active manipulation of second-order spatial quantum coherence,which exhibits the capability of switching between bunching and anti-bunching, by mapping the entanglement of spatially structured photons. We also show that signal processing based on quantum coherence exhibits robust resistance to intensity disturbance. Our findings not only enhance existing applications but also pave the way for broader utilization of higher-order spatial quantum coherence.

Manipulating propagation and evolution of polarization singularities in composite Bessel-like fields

Structured optical fields embedded with polarization singularities(PSs)have attracted extensive attention due to their capability to retain topological invariance during propagation.Many advances in PS research have been made over the past 20 years in the areas of mathematical description,generation and detection technologies,propagation dynamics,and applications.However,one of the most crucial and difficult tasks continues to be manipulating PSs with multiple degrees of freedom,especially in three-dimensional(3D)tailored optical fields.We propose and demonstrate the longitudinal PS lines obtained by superimposing Bessel-like modes with orthogonal polarization states on composite vector optical fields(VOFs).The embedded PSs in the fields can be manipulated to propagate robustly along arbitrary trajectories,or to annihilate,revive,and transform each other at on-demand positions in 3D space,allowing complex PS’topological morphology and intensity patterns to be flexibly customized.Our findings could spur further research into singular optics and help with applications such as micromanipulation,microstructure fabrication,and optical encryption.

Emergence of classical objectivity of quantum Darwinism in a photonic quantum simulator

Quantum-to-classical transition is a fundamental open question in physics frontier. Quantum decoherence theory points out that the inevitable interaction with environment is a sink carrying away quantum coherence, which is responsible for the suppression of quantum superposition in open quantum system.Recently, quantum Darwinism theory further extends the role of environment, serving as communication channel, to explain the classical objectivity emerging in quantum measurement process. Here, we used a six-photon quantum simulator to investigate classical and quantum information proliferation in quantum Darwinism process. In the simulation, many environmental photons are scattered from an observed quantum system and they are collected and used to infer the system's state. We observed redundancy of system's classical information and suppression of quantum correlation in the fragments of environmental photons. Our results experimentally show that the classical objectivity of quantum system can be established through quantum Darwinism mechanism.

Experimental test of generalized Hardy's paradox

Since the pillars of quantum theory were established, it was already noted that quantum physics may allow certain correlations defying any local realistic picture of nature, as first recognized by Einstein,Podolsky and Rosen. These quantum correlations, now termed quantum nonlocality and tested by violation of Bell's inequality that consists of statistical correlations fulfilling local realism, have found loophole-free experimental confirmation. A more striking way to demonstrate the conflict exists, and can be extended to the multipartite scenario. Here we report experimental confirmation of such a striking way, the multipartite generalized Hardy's paradoxes, in which no inequality is used and the conflict is stronger than that within just two parties. The paradoxes we consider here belong to a general framework [S.-H. Jiang et al., Phys. Rev. Lett. 120(2018) 050403], including previously known multipartite extensions of Hardy's original paradox as special cases. The conflict shown here is stronger than in previous multipartite Hardy's paradox. Thus, the demonstration of Hardy-typed quantum nonlocality becomes sharper than ever.

Curvilinear Poincaré vector beams

We develop a method for completely shaping optical vector beams with controllable amplitude, phase, and polarization gradients along three-dimensional freestyle trajectories. We design theoretically and demonstrate experimentally curvilinear Poincaré vector beams that exhibit high intensity gradients and accurate state of polarization prescribed along the beam trajectory.

Dual-curvilinear beam enabled tunable manipulation of high-and low-refractive-index particles

We present an innovative approach for the simultaneous agile manipulation of high-refractive-index(HRI) and low-refractive-index(LRI) particles. Our method involves introducing a dual-curvilinear optical vortex beam(DC-OVB) generated by superimposing a pair of curved beams: HRI and LRI particles are controlled by the bright curve and the dark channel between the two curves, respectively. The proposed DC-OVB provides customizable motion paths and velocities for both LRI and HRI particles. Each curve of the DC-OVB can support a distinct orbital flow density(OFD), enabling the application of torques to HRI and LRI particles, guiding them to orbit along specified trajectories and prompting them to execute various curvilinear motions simultaneously,including curvilinear movement, revolution, and rotation.