Xi-Feng Ren

Experimental Teleportation of a Quantum Controlled-NOT Gate

Teleportation of quantum gates is a critical step for the implementation of quantum networking and teleportation-based models of quantum computation. We report an experimental demonstration of teleportation of the prototypical quantum controlled-NOT (CNOT) gate. Assisted with linear optical manipulations, photon entanglement produced from parametric down-conversion, and postselection from the coincidence measurements, we teleport the quantum CNOT gate from acting on local qubits to acting on remote qubits. The quality of the quantum gate teleportation is characterized through the method of quantum process tomography, with an average fidelity of 0.84 demonstrated for the teleported gate.

Ordering Ag nanowire arrays by a glass capillary: A portable, reusable and durable SERS substrate

Assembly of nanowires into ordered macroscopic structures with new functionalities has been a recent focus. In this Letter, we report a new route for ordering hydrophilic Ag nanowires with high aspect ratio by flowing through a glass capillary. The present glass capillary with well-defined silver nanowire films inside can serve as a portable and reusable substrate for surface-enhanced Raman spectroscopy (SERS), which may provide a versatile and promising platform for detecting mixture pollutions. By controlling the flow parameters of nanowire suspensions, initially random Ag nanowires can be aligned to form nanowire arrays with tunable density, forming cambered nanowire films adhered onto the inner wall of the capillary. Compared with the planar ordered Ag nanowire films by the Langmuir-Blodgett (LB) technique, the cambered nanowire films show better SERS performance.

Broadband integrated polarization beam splitter with surface plasmon

A broadband integrated waveguide polarization beam splitter consisting of a metal nanoribbon and two dielectric waveguides is proposed and numerically investigated. This surface plasmon based device provides a unique approach for polarization sensitive manipulation of light in an integrated circuit and will be essential for future classical and quantum information processes.

Macroscopic‐Scale Alignment of Ultralong Ag Nanowires in Polymer Nanofiber Mat and Their Hierarchical Structures by Magnetic‐Field‐Assisted Electrospinning

1D nanomaterials have attracted explosive attention in the context of the physical and chemical fi elds, owing to their potential for novel applications in electronic and optical devices. [ 1 ] With the development of synthetic methodologies, 1D nanomaterials have achieved great success and a wide variety of different materials from organic polymers to inorganic compounds have been prepared. [ 2 , 3 ] Recently, research activities in the fi eld of nanoscience are shifting from the preparation of individual nanoparticles (NPs) to the preparation of NP assemblies and the realization of their applications. [ 4 ] From the viewpoint of application, assembly of these 1D nanomaterials into functional nanomaterials and devices is required, especially for alignment in large scale, which is still one of the most diffi cult problems hindering their applications. Various methods based on self-assembly or directed self-assembly techniques have been used to assemble nanomaterials into functional devices. Several reviews focused on assembly have also appeared. [ 4–6 ] However, most of these methods have been applied to assemble 1D nanostructures with low aspect ratios, such as NPs and nanorods (NRs); few techniques have been successfully applied to assemble nanowires (NWs) with high aspect ratios because the magnitude and range of the repulsive forces of wires, rods, and

Coupling of light from an optical fiber taper into silver nanowires

We report the coupling of photons from an optical fiber taper to surface plasmon modes of silver nanowires. The coupling efficiency can be modulated by adjusting the cross angle and the polarization of the input light. The launch of propagating plasmons can be realized not only at ends of the nanowires but also at the midsection. In addition, we present the coupling of light into multiple nanowires from a single optical fiber taper simultaneously. Our demonstration offers an efficient method for optimizing plasmon coupling into nanoscale metallic waveguides and promotes the realization of highly integrated plasmonic devices.

Plasmon-assisted transmission of high-dimensional orbital angular-momentum entangled state

We present an experimental evidence that high-dimensional orbital angular-momentum entanglement of a pair of photons can be survived after a photon-plasmon-photon conversion. The information of spatial modes can be coherently transmitted by surface plasmons. This experiment primarily studies the high-dimensional entangled systems based on surface plasmon with subwavelength structures. It maybe useful in the investigation of spatial-mode properties of surface plasmon-assisted transmission through subwavelength hole arrays.

One-pot colloidal chemistry route to homogeneous and doped colloidosomes.

Colloidosomes are usually produced from a series of building blocks with different sizes ranging from several nanometers to micrometers or various shapes, such as particles, microrods, and quantum dots. Colloidosomes can possess a variety of characteristics in terms of photics, electrology, mechanical strength, and selective permeability, derived from their building blocks. However, poor mechanical stability and complicated synthesis processes have limited the applications of colloidosomes. Here, we report a new one-pot colloidal chemistry route to synthesize phenol formaldehyde resin (PFR), Ag@PFR, and Au@PFR colloidosomes with high yields. The method can be modified to synthesize different kinds of doped colloidosomes with different components, which will provide a new approach to design colloidosomes with different functions.

Detecting orbital angular momentum through division-of-amplitude interference with a circular plasmonic lens.

We demonstrate a novel detection scheme for the orbital angular momentum (OAM) of light using circular plasmonic lens. Owing to a division-of-amplitude interference phenomenon between the surface plasmon waves and directly transmitted light, specific intensity distributions are formed near the plasmonic lens surface under different OAM excitations. Due to different phase behaviors of the evanescent surface plasmon wave and the direct transmission, interference patterns rotate as the observation plane moves away from the lens surface. The rotation direction is a direct measure of the sign of OAM, while the amount of rotation is linked to the absolute value of the OAM. This OAM detection scheme is validated experimentally and numerically. Analytical expressions are derived to provide insights and explanations of this detection scheme. This work forms the basis for the realization of a compact and integrated OAM detection architect that may significantly benefit optical information processing with OAM states.

High-Visibility On-Chip Quantum Interference of Single Surface Plasmons

Quantum photonic integrated circuits (QPICs) based on dielectric waveguides have been widely used in linear optical quantum computation. Recently, surface plasmons have been introduced to this application because they can confine and manipulate light beyond the diffraction limit. In this study, the on-chip quantum interference of two single surface plasmons was achieved using dielectric-loaded surface-plasmon-polariton waveguides. The high visibility (greater than 90%) proves the bosonic nature of single plasmons and emphasizes the feasibility of achieving basic quantum logic gates for linear optical quantum computation. The effect of intrinsic losses in plasmonic waveguides with regard to quantum information processing is also discussed. Although the influence of this effect was negligible in the current experiment, our studies reveal that such losses can dramatically reduce quantum interference visibility in certain cases; thus, quantum coherence must be carefully considered when designing QPIC devices.

In-line high efficient fiber polarizer based on surface plasmon

An in-line high efficient polarizer, composed of tapered fiber on the Au thin film, is theoretically proposed and experimentally demonstrated. The protocol is based on the high efficient adiabatic conversion of transverse magnetic mode from tapered fiber into surface plasmon (SP) and attenuates quickly in metal film. On the contrary, the transverse electric polarized light is influenced hardly in the whole process. The polarization extinction ratio higher than 500:1 (≈27 dB) is obtained in our experiment. Our demonstration offers a potential way to manipulate the polarization of light in integrated circuit and may inspirit more attention to surface plasmon based devices for polarization controlling.