Polarization-dependent Beam Splitter Research Articles

Efficient infrared nine-channel reflective polarization-dependent splitter

In order to meet the requirements of a multi-beam splitter in optical communication systems, an efficient infrared nine-channel reflective polarization-dependent beam splitter based on an addition-shaped ridge structure is proposed. All structural parameters of this polarization-dependent beam splitter are derived from the rigorous coupled-wave analysis. Upon the vertical entry of a plane wave with a wavelength of 800 nm into the grating, for transverse magnetic polarization, the diffraction efficiencies are 10.66%, 10.69%, 10.69%, 10.65%, and 10.67% at 0th, ±1st, ±2nd, ±3rd and ±4th orders, respectively. For transverse electric polarization, the diffraction efficiencies of the 0th, ±1st, ±2nd, ±3rd and ±4th orders are 10.79%, 10.86%, 10.88%, 10.84%, and 10.86%, respectively. In addition, the tolerance analysis in this paper reveals the practicality and efficiency of this beam splitter. Therefore, the addition-shaped ridge structure has a good performance of uniformity and broad application prospects in nine-channel reflective applications.

Topological and hyperbolic dielectric materials from chirality-induced charge-parity symmetry

Parity-time $(\mathcal{PT})$ symmetry, originally conceived for non-Hermitian open quantum systems, has opened an exciting avenue towards coherent control of light for significant applications. Here we propose a paradigm towards non-Hermitian photonics based on the charge-parity $(\mathcal{CP})$ symmetry, in which the charge conjugation and parity symmetries are broken individually but preserved jointly. Such a symmetry-breaking scheme induces a transition from dielectric to hyperbolic dispersions in chiral dielectrics, leading to lossless all-dielectric hyperbolic metamaterials. More interestingly, the $\mathcal{CP}$-symmetry transition represents a non-Hermitian topological phase transition that occurs at infinite energy and requires no explicit band gap closing. We further showcase broad applications of $\mathcal{CP}$-symmetric photonics such as an all-angle polarization-dependent beam splitter and enhanced spontaneous emission. The $\mathcal{CP}$ symmetry opens an unexplored pathway for non-Hermitian topological photonics by bringing new physics into strong chiral metamaterials, therefore providing a powerful tool for engineering many promising applications in photonics and other related fields.

Macroscopic wave-optical simulation of dielectric metasurfaces.

We propose a novel method for the wave-optical simulation of diffractive optical elements (DOEs) like metasurfaces or computer-generated holograms (CGHs). Existing techniques mostly rely on the assumption of local periodicity to predict the performance of elements. The utilization of a specially adapted finite-difference beam propagation method (BPM) allows the semi-rigorous simulation of entire DOEs within a reasonable runtime due to linear scaling with the number of grid points. Its applicability is demonstrated by the simulation of a metalens and a polarization-dependent beamsplitter, both based on effective-medium metasurfaces. A comparison shows high conformity to rigorous simulations.

W states fusion via polarization-dependent beam splitter

Based on the polarization-dependent beam splitter (PDBS), we propose an optical scheme to fuse small-size polarization entangled W states into a large-scale W states. With the present scheme, two $$W_{m+n+t-2}$$ states can be created from an n-qubit W state, an m-qubit W state and a t-qubit W state, and two $$W_{m+n+t+q-3}$$ states can be generated from $$W_m$$ , $$W_n$$ , $$W_t$$ and $$W_q$$ states. In the previous fusion schemes, only one particle from each initial W state is allowed to enter the fusion mechanism, but with the progress of experimental technology, two particles can be extracted. In this case, the W states fusion of our scheme will be realized without any ancillary particles and controlled quantum gate. In addition, compared with the one target W state obtained in previous preparation schemes, our scheme can generate two large-scale W states, which effectively improve the success rate of generating target W state. The ability to generate two target W states makes our scheme have a distinct advantage in preparing W states with larger particle numbers. This preparation mechanism also can be generalized to the case of fusing more different or same particles W states.

Preparing large-scale maximally entangled W states in optical system

We propose an optical scheme to prepare large-scale maximally entangled W states by fusing arbitrary-size polarization entangled W states via polarization-dependent beam splitter. Because most of the currently existing fusion schemes are suffering from the qubit loss problem, that is the number of the output entangled qubits is smaller than the sum of numbers of the input entangled qubits, which will inevitably decrease the fusion efficiency and increase the number of fusion steps as well as the requirement of quantum memories, in our scheme, we design a effect fusion mechanism to generate $$W_{m+n}$$ state from a n-qubit W state and a m-qubit W state without any qubit loss. As the nature of this fusion mechanism clearly increases the final size of the obtained W state, it is more efficient and feasible. In addition, our scheme can also generate $$W_{m+n+t-1}$$ state by fusing a $$W_m$$ , a $$W_n$$ and a $$W_t$$ states. This is a great progress compared with the current scheme which has to lose at least two particles in the fusion of three W states. Moreover, it also can be generalized to the case of fusing k different W states, and all the fusion schemes proposed here can start from Bell state as well.

High-efficiency terahertz polarization devices based on the dielectric metasurface

Metasurfaces are composed of the subwavelength structures, which can be used to manipulate the amplitude, phase, and polarization of incident electromagnetic waves efficiently. Here, we propose a novel type of dielectric metasurface based on crystal Si for realizing to manipulate the terahertz wave, in which by varying the geometric sizes of the Si micro-bricks, the transmitting phase of the terahertz wave can almost span over the entire 2π range for both of the x-polarization and y-polarization simultaneously, while keeping the similarly high-transmission amplitudes (over 90%). At the frequency of 1.0 THz, we have successfully designed a series of controllable THz devices, such as the polarization-dependent beam splitter, polarization-independent beam deflector and the focusing lenses based on the designed metasurfaces. Our designs are easy to fabricate and can be promising in developing high-efficiency THz functional devices.

A 14 × 14 μm(2) footprint polarization-encoded quantum controlled-NOT gate based on hybrid waveguide.

Photonic quantum information processing system has been widely used in communication, metrology and lithography. The recent emphasis on the miniaturized photonic platform is thus motivated by the urgent need for realizing large-scale information processing and computing. Although the integrated quantum logic gates and quantum algorithms based on path encoding have been successfully demonstrated, the technology for handling another commonly used polarization-encoded qubits has yet to be fully developed. Here, we show the implementation of a polarization-dependent beam-splitter in the hybrid waveguide system. With precisely design, the polarization-encoded controlled-NOT gate can be implemented using only single such polarization-dependent beam-splitter with the significant size reduction of the overall device footprint to 14 × 14 μm2. The experimental demonstration of the highly integrated controlled-NOT gate sets the stage to develop large-scale quantum information processing system. Our hybrid design also establishes the new capabilities in controlling the polarization modes in integrated photonic circuits.

Fusion of W-like states in optical system

An effective scheme is proposed for preparing large-scale maximally entangled W states by fusing arbitrary-size polarization entangled W or W-like states via polarization-dependent beam splitter (PDBS). In our scheme, Wm+n−1 state can be generated from an n-qubit W state and an m-qubit W state, and Wm+n+t−2 state can be generated from Wm, Wn and Wt states. The fusion process can start with Bell states too. Because PDBS has selective transmission rates for different polarization states, our fusion has a distinct property, i.e. a large-scale maximally entangled W state can be generated by fusing small-size W-like states, and the cost analyses indicate that our fusion scheme is more efficient than the previous one in fusing W-like states. In addition, there is no need for any controlled quantum gate and any ancillary photon in our scheme, so it is simple and feasible.

Optimal cloning of arbitrary mirror-symmetric distributions on the Bloch sphere: a proposal for practical photonic realization

We study state-dependent quantum cloning that can outperform universal cloning (UC). This is possible by using some a priori information on a given quantum state to be cloned. Specifically, we propose a generalization and optical implementation of quantum optimal mirror phase-covariant cloning, which refers to optimal cloning of sets of qubits of known modulus of the expectation value of Pauli's Z operator. Our results can be applied to cloning of an arbitrary mirror-symmetric distribution of qubits on the Bloch sphere including in special cases UC and phase-covariant cloning. We show that the cloning is optimal by adapting our former optimality proof for axisymmetric cloning (Bartkiewicz and Miranowicz 2010 Phys. Rev. A 82 042330). Moreover, we propose an optical realization of the optimal mirror phase-covariant 1→2 cloning of a qubit, for which the mean probability of successful cloning varies from 1/6 to 1/3 depending on prior information on the set of qubits to be cloned. The qubits are represented by polarization states of photons generated by the type-I spontaneous parametric down-conversion. The scheme is based on the interference of two photons on an unbalanced polarization-dependent beam splitter with different splitting ratios for vertical and horizontal polarization components and the additional application of feedforward by means of Pockels cells. The experimental feasibility of the proposed setup is carefully studied including various kinds of imperfections and losses. Moreover, we briefly describe two possible cryptographic applications of the optimal mirror phase-covariant cloning corresponding to state discrimination (or estimation) and secure quantum teleportation.

Optimal local expansion ofWstates using linear optics and Fock states

We derive the maximum success probability of the circuits with passive linear optics for expanding an N-photon W state to an (N + n)-photon W state, by accessing only one photon of the initial W state and adding n photons in a Fock state. We show that the maximum success probability is achieved by a polarization-dependent beamsplitter and n-1 polarization-independent beamsplitters.

Local expansion of photonic W state using a polarization-dependent beamsplitter

We propose a simple probabilistic optical gate to expand polarization entangled W states. The gate uses one polarization-dependent beamsplitter and a horizontally polarized single photon as an ancilla. The gate post-selectively expands N-photon W states to (N+1)-photon W states. A feasibility analysis considering the realistic experimental conditions shows that the scheme is within the reach of the current quantum optical technologies.

A simple scheme for expanding a polarization-entangled W state by adding one photon

We propose a simple scheme for expanding a polarization-entangled W state. By mixing a single photon and one of the photons in an n-photon W state at a polarization-dependent beam splitter (PDBS), we can obtain an (n + 1)-photon W state after post-selection. Our scheme also opens the door to generating n-photon W states using single photons and linear optics.

EXPERIMENTAL ANALYSIS OF A SIMPLE LINEAR OPTICS PHASE GATE

Linear optics two-qubit logic gates are essential tools in photonic quantum information. We describe a recently introduced simple conditional phase gate for photons, which relies on only one second order interference at a polarization dependent beam splitter, thereby making additional stability precautions dispensable. The improved quality of the gate is evaluated by performing full process tomography. The obtained process tomography data is fitted by a model based on experimental parameters of the setup which allows predictions on the performance of the gate in multi-photon experiments. .

Linear Optics Controlled-Phase Gate Made Simple

Linear optics quantum logic gates are the best tool to generate multiphoton entanglement. Simplifying a recent approach, we were able to implement the conditional phase gate with only one second-order interference at a polarization dependent beam splitter, thereby significantly increasing its stability. The improved quality of the gate is evaluated by analyzing its entangling capability and by performing full process tomography. The achieved results ensure that this device is well suited for implementation in various multiphoton quantum information protocols.

Polarization-based balanced heterodyne detection method in a Sagnac interferometer for precision phase measurement

We describe a balanced heterodyne detection method for a Sagnac interferometer that uses a polarization-dependent beam splitter. The signal and the local oscillator are orthogonally polarized components of a single laser beam, permitting the detection of the signal by subtraction of two photocurrents produced in appropriate polarization projections. Using this scheme, we experimentally demonstrate a phase measurement with a sensitivity of 9x10(-10) rad/ radicalHz. The measurement is robust in the presence of laser frequency noise, as a result of preserving the common-path nature of the Sagnac interferometer, and of laser-amplitude noise, as a result of balanced detection.