Parallel Image Processing Algorithms Based on Mathematical Morphology Using a Multiple-Imaging System

Morphological techniques are applied to binary image processors in a multiple-imaging optical system and the following algorithms are proposed: performing morphological basic operations, extraction of boundary lines, detection of characteristic points in small-scale patterns, elimination of salt noises with few pixels, and smoothing of boundaries. Techniques for processing a complicated binary image are demonstrated using the algorithms and a hybrid parallel computing system with a simple optical multiple-imaging system and a personal computer.     

Quantum Network Coding on Networks with Arbitrarily Distributed Hidden Channels

Although perfect quantum network coding has been proved to be achievable,it is still puzzling whether it is feasible whenever one or more of the channels are replaced by the hidden ones emerging from quantum entanglement.The question is answered in this paper.First,we propose a quantum network coding protocol over a butterfly network with two hidden channels.Second,we investigate a more general situation,where d-level quantum letters are transmitted through the network containing arbitrarily distributed hidden channels,and prove that quantum network coding on such networks is still achievable.     

Quantum Network Coding on Networks with Arbitrarily Distributed Hidden Channels

Although perfect quantum network coding has been proved to be achievable, it is still puzzling whether it is feasible whenever one or more of the channels are replaced by the hidden ones emerging from quantum entanglement. The question is answered in this paper. First, we propose a quantum network coding protocol over a butterfly network with two hidden channels. Second, we investigate a more general situation, where d-level quantum letters are transmitted through the network containing arbitrarily distributed hidden channels, and prove that quantum network coding on such networks is still achievable.     

Implementtion of a Computation Algorithm for Deutsch-Jozsa Problem Utilizing Spatial Distribution of Photons

Several implementations of quantum computation making effective use of the quantum behavior of single-photons have been explored. These implementing methods were found unsuitble for large-scale computation, because they require 2^N-1 optical paths to represent N qubits. In this paper, a new computing scheme is described which utilizes spatial distribution of photons. The occupation of several optical paths by single-photons is adopted as qubits. This adoption gives several extension of processing capacity and computational functionality with a simple setup. An optical implementation of a solution algorithm on four-bit Deutsch-Jozsa problem is demonstrated with utilization of the spatial distribution of photons.     

Revisiting Controlled Quantum Secure Direct Communication Using a Non-symmetric Quantum Channel with Quantum Superdense Coding

Recently Xia and Song [Phys. Lett. A 364 （2007） 117] have proposed a controlled quantum secure direct communication （CQSDC） protocol. They claimed that in their protocol only with the help of the controller Charlie, the receiver Alice can successfully extract the secret message from the sender Bob. In this letter, first we will show that within their protocol the controller Charlie＇s role could have been excluded if it were not for their unreasonable design. We then revise the Xia-Song CQSDC protocol such that its original advantages are reta/ned and the CQSDC can be really realized.     

Quantum Dense Coding Without Joint Measurement

We propose two schemes for quantum dense coding without Bell states measurement. One is deterministic, the other is probabilistic. In the deterministic scheme, the initial entangled state will be not destructed. In the proba-bilistic scheme, the initial unknown nonmaximal entangled state will be transformed into a maximal entangled one. Our schemes require two auxiliary particles and perform single-qubit measurements on them. Thus our schemes are simple and economic.     

Photonic quantum information processing

Information processing with light is ubiquitous, from communication, metrology and imaging to computing. When we consider light as a quantum mechanical object, new ways of information processing become possible. In this review I give an overview of how quantum information processing can be implemented with single photons, and what hurdles still need to be overcome to implement the various applications in practice. I will place special emphasis on the quantum mechanical properties of light that make it different from classical light, and how these properties relate to quantum information processing tasks.     

Quantum Dense Coding Without Joint Measurement

We propose two schemes for quantum dense coding without Bell states measurement. One is deterministic, the other is probabilistic. In the deterministic scheme, the initial entangled state will be not destructed. In the probabilistic scheme, the initial unknown nonmaximal entangled state will be transformed into a maximalentangled one. Our schemes require two auxiliary particles and perform single-qubit measurements on them. Thus our schemes are simple and economic.     

Quantum Teleportation and Dense Coding in Multiple Bosonic Reservoirs

The effect of a reservoir on quantum communication depends on its spectral density. The efficiency of quantum teleportation and dense coding is explored when each one of the channel qubits is coupled simultaneously to multiple bosonic reservoirs. It is shown that the non-Markovianity triggered by increasing the reservoir number can induce revivals of quantum advantages of the two protocols after their disappearance. However, the backflow of information to the system that signifies non-Markovianity does not always induce immediate revivals of the quantum advantages. There may be a delayed effect for some initial states, and only as the backflow of information accumulates to a certain extent can the revivals of quantum advantages be triggered.     

基于改进量子粒子群的分布式并行计算框架设计

为了实现用户任务在大规模计算机集群上进行高效地处理,并克服现有并行计算框架通用性不强的缺点,提出了一种基于改进量子群算法和Map-Reduce模型的通用并行计算框架;首先,对经典的Map-Reduce分布式并行计算框架以及并行计算流程进行了具体描述;然后,基于改进的量子粒子群算法设计了改进的Map-Reduce模型,在Map阶段通过多种群并行搜索并计算所有粒子适应度,在Shuffle和Sort 阶段实现粒子的排序和种群的重新划分,然后在Reduce阶段更新控制系数和粒子位置,当最优解不变时,通过混沌扰动对其进行扰动;仿真实验表明同,文中设计的基于改进量子粒子群算法和Map-Reduce模型能高效地执行任务,较传统的Map-Reduce模型具有较少的执行时间,具有很强的可行性,是一种有效的通用并行计算模型。     

Scheme for Quantum Dense Coding with Secret Sharing in Cavity QED

Quantum dense coding （QDC） is a process originally proposed to send two classical bits information from a sender to a receiver by sending only one qubit. Our scheme of QDC is proposed following some ideas on secret sharing with entanglement in cavity QED. Based on the theory of secret sharing the QDC process can be more secure.     

Quantum Density Peak Clustering Algorithm

A widely used clustering algorithm, density peak clustering (DPC), assigns different attribute values to data points through the distance between data points, and then determines the number and range of clustering by attribute values. However, DPC is inefficient when dealing with scenes with a large amount of data, and the range of parameters is not easy to determine. To fix these problems, we propose a quantum DPC (QDPC) algorithm based on a quantum DistCalc circuit and a Grover circuit. The time complexity is reduced to O(log(N2)+6N+N), whereas that of the traditional algorithm is O(N2). The space complexity is also decreased from O(N·⌈logN⌉) to O(⌈logN⌉).     

A Spatial Domain Quantum Watermarking Scheme

This paper presents a spatial domain quantum watermarking scheme. For a quantum watermarking scheme, a feasible quantum circuit is a key to achieve it. This paper gives a feasible quantum circuit for the presented scheme. In order to give the quantum circuit, a new quantum multi-control rotation gate, which can be achieved with quantum basic gates, is designed. With this quantum circuit, our scheme can arbitrarily control the embedding position of watermark images on carrier images with the aid of auxiliary qubits. Besides reversely acting the given quantum circuit, the paper gives another watermark extracting algorithm based on quantum measurements. Moreover, this paper also gives a new quantum image scrambling method and its quantum circuit. Differ from other quantum watermarking schemes, all given quantum circuits can be implemented with basic quantum gates. Moreover, the scheme is a spatial domain watermarking scheme, and is not based on any transform algorithm on quantum images. Meanwhile, it can make sure the watermark be secure even though the watermark has been found. With the given quantum circuit, this paper implements simulation experiments for the presented scheme. The experimental result shows that the scheme does well in the visual quality and the embedding capacity.     

Simplification of Space-Variant Parallel Logic Operations Using the Temporal Method

A time-domain encoding method (temporal method) for space-variant parallel logic operations, which can execute different operations in parallel, is proposed. The temporal method is based on temporal encoding of two input patterns, temporal gating of the coded pattern, and decoding by temporal addition of the gated patterns. The first feature of the proposed method is that parallel logic operations can be performed without complex pattern transformations. The second feature is that the logical output can be directly fed to succeeding systems without specific decoding. Therefore, the logic operation system can be constructed using conventional optics and existing spatial light modulators. In order to confirm these features, an optoelectronic experimental system is constructed and space-variant parallel logic operations are performed.     

Performance Comparison and Evaluation of Options for Arranging Data in Digital Optical Parallel Computing

Performances of options for arranging data in the input images of digital optical computing are analyzed and evaluated on the basis of the characteristic functions that the authors formularized. The methods for arranging the data are classified into two options: the spatially expanded bit-pattern arrangement (SEPA) and the bit-slice arrangement (BSA). To analyze and evaluate the performance, the options are applied to the parallel operations based on the optical array logic that is a paradigm of digital parallel computing. Processing steps, storage capacity, and scale of the operation kernel required for performing various parallel operations are analyzed as the characteristic functions. The performances of the SEPA and the BSA are evaluated by comparing these functions. The features of each option are clarified and a guideline for choosing the optimal option is proposed to efficiently perform digital parallel optical operations.     

High-Fidelity and Low-Cost Hyperparallel Quantum Gates for Photon Systems via Λ-Type Systems

Quantum gates designed with minimized resources overhead have a crucial role in quantum information processing. Here, based on the degrees of freedom (DoFs) of photons and Λ-type atom systems, two high-fidelity and low-cost protocols are presented for realizing polarization-spatial hyperparallel controlled-not (CNOT) and Toffoli gates on photon systems with only two and four two-qubit polarization–polarization swap (P-P-SWAP) gates in each DoF, respectively. Moreover, the quantum gates can be extended feasibly to construct 2m-target-qubit hyperparallel CNOT and 2n-control-qubit Toffoli gates required only 4m and 4n P-P-SWAP gates on $(m+1)$- and $(n+1)$-photon systems, respectively, which dramatically lower the costs and bridge the divide between the theoretical lower bounds and the current optimal syntheses for the photonic quantum computing. Further, the unique auxiliary atom of these quantum gates can be regarded as a temporary quantum memory that requires no initialization and measurement, and is reused within the coherence time, as the state of the atom remains unchanged after the hyperparallel quantum computing.     

基于六光子量子避错码的量子密钥分发方案

量子信道中不可避免存在的噪声将扭曲被传输的信息,对通信造成危害。目前克服量子信道噪声的较好方案是量子避错码（QEAC）。将量子避错码思想用于量子密钥分发,能有效克服信道中的噪声,且无需复杂的系统。用六光子构造了量子避错码,提出了一种丛于六光子避错码的量子密钥分发（QDK）方案。以提高量子密钥分发的量子比特效率和安全性为前提,对六光子避错码的所有可能态进行组合,得到一种六光子避错码的最优组合方法,可将两比特信息编码在一个态中,根据测肇结果和分组信息进行解码,得到正确信息的平均概率为7／16。与最近的基于四光子避错码的克服量子信道噪声的量子密钥分发方案相比,该方案的量子比特效率提高了16．67％,密钥分发安全性足它的3．5倍。     

Quantum computing by optical control of electron spins

We review the progress and main challenges in implementing large-scale quantum computing by optical control of electron spins in quantum dots (QDs). Relevant systems include self-assembled QDs of III–V or II–VI compound semiconductors (such as InGaAs and CdSe), monolayer fluctuation QDs in compound semiconductor quantum wells, and impurity centres in solids, such as P-donors in silicon and nitrogen-vacancy centres in diamond. The decoherence of the electron spin qubits is discussed and various schemes for countering the decoherence problem are reviewed. We put forward designs of local nodes consisting of a few qubits which can be individually addressed and controlled. Remotely separated local nodes are connected by photonic structures (microcavities and waveguides) to form a large-scale distributed quantum system or a quantum network. The operation of the quantum network consists of optical control of a single electron spin, coupling of two spins in a local nodes, optically controlled quantum interfacing between stationary spin qubits in QDs and flying photon qubits in waveguides, rapid initialization of spin qubits and qubit-specific single-shot non-demolition quantum measurement. The rapid qubit initialization may be realized by selectively enhancing certain entropy dumping channels via phonon or photon baths. The single-shot quantum measurement may be in situ implemented through the integrated photonic network. The relevance of quantum non-demolition measurement to large-scale quantum computation is discussed. To illustrate the feasibility and demand, the resources are estimated for the benchmark problem of factorizing 15 with Shor's algorithm.     

应用费希尔信息量评价函数的波前编码系统设计

在兼顾图像恢复能力的基础上,将不同物距下点扩展函数相似性的评价函数费希尔信息量(Fisher Information,FI)应用到波前编码实际光学系统相位板的优化设计中。在焦距和孔径之比为3、有效焦距为100 mm的无穷远成像的双胶合系统的基础上,设计得到了双胶合-波前编码系统。通过解码前后的点扩展函数模拟和实验结果表明,该系统在5 m到无穷远的物距范围内很好地调制了系统的点扩展函数,使得它对物距不敏感。最后通过对位于5 m,10 m和15 m的三人分别进行传统双胶合成像和双胶合-波前编码系统的成像实验对比,有力地证明了双胶合系统的清晰成像的物距范围从10 m到无穷远扩展到5 m到无穷远,这使得光学系统景深得到很大的延拓。