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1.
On the basis of elementary transformation,we propose a new method for constructing a class of pure quantum codes [[n-i,2k-n+i,d-i]]2 and [[n+1,2k-n-1,d+1]]2 from a class of classical linear codes [n,k,d]2 that contain their dual codes.The construction process was based on the elementary algebra;the error-correcting performance of the quantum codes was analyzed according to the relationship between the parity-check matrix and the minimum distance of the classical linear codes;the encoding and decoding networks were constructed based on the stabilizer.The proposed method is simple,straightforward and easy to implement using a computer and other hardware system.The theoretical results showed that the method is practical for the construction of a class of quantum codes.  相似文献   

2.
Quantum information theory is a new interdisciplinary research field related to quantum mechanics, computer science, information theory, and applied mathematics. It provides completely new paradigms to do information processing tasks by employing the principles of quantum mechanics. In this review, we first survey some of the significant advances in quantum information theory in the last twenty years. We then focus mainly on two special subjects: discrimination of quantum objects and transformations between entanglements. More specifically, we first discuss discrimination of quantum states and quantum apparatus in both global and local settings. Secondly, we present systematical characterizations and equivalence relations of several interesting entanglement transformation phenomena, namely entanglement catalysis, multiple-copy entanglement transformation, and partial entanglement recovery.  相似文献   

3.
The quantum router is a key part of a quantum network. How to design a fully quantum router is a dominant theme in the area of quantum communication. Based on the cross-phase modulation technique, we propose a scheme to realize an optical quantum router using the c-path operation for its basic operation. This router is a perfect, fully quantum router, and it is available for arbitrary (separated or entangled) input signals and covers all possible control modes (the general n-control-m mode). Moreover, this router protects target signals and preserves quantum features, such as coherent superposition and entanglement. This is a new and powerful feature when compared with classical routers. With the development of current experimental technology, our scheme is feasible.  相似文献   

4.
Two fundamental problems exist in the use of quantum computation to process an image or signal.The first one is how to represent giant data,such as image data,using quantum state without losing information.The second one is how to load a colossal volume of data into the quantum registers of a quantum CPU from classical electronic memory.Researches on these two questions are rarely reported.Here an entangled state is used to represent an image(or vector)for which two entangled registers are used to store a vector component and its classical address.Using the representation,n1+n2+8 qubits are used to store the whole information of the gray image that has a 2n1×2n2 size at a superposition of states,a feat is not possible with a classic computer.The way of designing a unitary operation to load data,such as a vector(or image),into the quantum registers of a quantum CPU from electronic memory is defined herein as a quantum loading scheme(QLS).In this paper,the QLS with time complexity O(log2N)is presented where N denotes the number of vector components,a solution that would break through the efciency bottleneck of loading data.QLS would enable a quantum CPU to be compatible with electronic memory and make possible quantum image compression and quantum signal processing that has classical input and output.  相似文献   

5.
Lyapunov equation is one of the most basic and important equations in control theory, which has various applications in, e.g., stability analysis and robust analysis of linear control systems. Inspired by the recent progresses of quantum algorithms, we find that solving Lyapunov equation can be exponentially accelerated by quantum algorithms rather than traditional classical algorithms. Our algorithm is more efficient especially when the system matrix is sparse and has a low condition number. The results presented in this paper open up new dimensions of research in controlling classical system by quantum information processors, which has rarely been considered in the existing literature.  相似文献   

6.
Edge extraction is an indispensable task in digital image processing. With the sharp increase in the image data, real-time problem has become a limitation of the state of the art of edge extraction algorithms.In this paper, QSobel, a novel quantum image edge extraction algorithm is designed based on the flexible representation of quantum image(FRQI) and the famous edge extraction algorithm Sobel. Because FRQI utilizes the superposition state of qubit sequence to store all the pixels of an image, QSobel can calculate the Sobel gradients of the image intensity of all the pixels simultaneously. It is the main reason that QSobel can extract edges quite fast. Through designing and analyzing the quantum circuit of QSobel, we demonstrate that QSobel can extract edges in the computational complexity of O(n2) for a FRQI quantum image with a size of2 n × 2n. Compared with all the classical edge extraction algorithms and the existing quantum edge extraction algorithms, QSobel can utilize quantum parallel computation to reach a significant and exponential speedup.Hence, QSobel would resolve the real-time problem of image edge extraction.  相似文献   

7.
The quantum phenomena of electromagneticalty induced transparency (EIT) or plasmonic ana- logue of electromagnetically induced transparency (PIT) can be mimicked in the classical resonators, leading to a unique way to explore the coherent coupling mechanism in metamaterial systems. Various metamaterial structures have been proposed to excite and manipulate the PIT effect with flexibility and performance with geometry-controllable, polarizatiomindependent, broadband-transparency and active-modulated characteristics. These in turn promise the fascinating functionalities and applications of the PIT effects, such as slow-light com- ponents, nonlinear devices and high-sensitivity sensors. Here, we present a review on the progress in developing the PIT effect in terahertz metamaterials over the past few years.  相似文献   

8.
Devices based on the optical microcavities which confine light to small volumes by resonant recircu- lation are already indispensable for a wide range of studies and applications. This article provides an overview of the development and application of optical microcavities. We first give a pedagogical introduction to the in- teraction between a two-level system and a quantized electromagnetic field in the cavity, based on the so-called Jaynes-Cummings model, which is basic and important theory model in the cavity quantum electrodynamics, and various quantum phenomena and applications of it. Then, we overview three basic types of the microcavity structures, and also highlight the progress achieved so far in these systems. Based on these three structures, we give an account of three representative applications of optical microcavities, and explain their microcavity requirements and the state of the art for these devices, before outlining the challenges for the future.  相似文献   

9.
图像拼接技术   总被引:12,自引:0,他引:12  
Image mosaics have been an active area of research in the fields of computer vision,image processing and computer graphics in recent years.The automatic fast construction of unlimited field of view,high-resolution image mosaics is a main research task of this area.According to the procedure of image mosaics,the paper introduces and discusses image acquisition,geometric corrections,image register and image blending in detail.In the last part of the paper,we make a discussion on some problems of research and point out the future research directiions.  相似文献   

10.
Stereo matching is a fundamental and crucial problem in computer vision. In the last decades, many researchers have been working on it and made great progress. Generally stereo algorithms can be classified into local methods and global methods. In this paper, the challenges of stereo matching are first introduced, and then we focus on local approaches which have simpler structures and higher efficiency than global ones. Local algorithms generally perform four steps: cost computation, cost aggregation, disparity computation and disparity refinement. Every step is deeply investigated, and most work focuses on cost aggregation. We studied most of the classical local methods and divide them into several classes. The classification well illustrates the development history of local stereo correspondence and shows the essence of local matching along with its important and difficult points. At the end we give the future development trend of local methods.  相似文献   

11.
量子计算机具有许多与经典计算机不同的量子特性,其性能远远优于经典计算机,但量子力学特有的性质也使得量子计算机的设计方法不同于经典计算机。在量子计算机中应用经典计算机的存储层次将会遇到一些前所未有的困难,文章提出了一种解决方案,以便能够在量子计算机的存储系统中应用与经典计算机类似的层次结构来提高访存性能。最后,文章给出了这种层次结构下访存性能的分析结果,指出了在何种条件下才能最大程度地发挥层次结构的性能。  相似文献   

12.
Although quantum algorithms realizing an exponential time speed-up over the best known classical algorithms exist, no quantum algorithm is known performing computation using less space resources than classical algorithms. In this paper, we study, for the first time explicitly, space-bounded quantum algorithms for computational problems where the input is given not as a whole, but bit by bit. We show that there exist such problems that a quantum computer can solve using exponentially less work space than a classical computer. More precisely, we introduce a very natural and simple model of a space-bounded quantum online machine and prove an exponential separation of classical and quantum online space complexity, in the bounded-error setting and for a total language. The language we consider is inspired by a communication problem (the disjointness function) that Buhrman, Cleve and Wigderson used to show an almost quadratic separation of quantum and classical bounded-error communication complexity. We prove that, in the framework of online space complexity, the separation becomes exponential.  相似文献   

13.
The standard setting of quantum computation for continuous problems uses deterministic queries and the only source of randomness for quantum algorithms is through measurement. Without loss of generality we may consider quantum algorithms which use only one measurement. This setting is related to the worst case setting on a classical computer in the sense that the number of qubits needed to solve a continuous problem must be at least equal to the logarithm of the worst case information complexity of this problem. Since the number of qubits must be finite, we cannot solve continuous problems on a quantum computer with infinite worst case information complexity. This can even happen for continuous problems with small randomized complexity on a classical computer. A simple example is integration of bounded continuous functions. To overcome this bad property that limits the power of quantum computation for continuous problems, we study the quantum setting in which randomized queries are allowed. This type of query is used in Shor’s algorithm. The quantum setting with randomized queries is related to the randomized classical setting in the sense that the number of qubits needed to solve a continuous problem must be at least equal to the logarithm of the randomized information complexity of this problem. Hence, there is also a limit to the power of the quantum setting with randomized queries since we cannot solve continuous problems with infinite randomized information complexity. An example is approximation of bounded continuous functions. We study the quantum setting with randomized queries for a number of problems in terms of the query and qubit complexities defined as the minimal number of queries/qubits needed to solve the problem to within ɛ by a quantum algorithm. We prove that for path integration we have an exponential improvement for the qubit complexity over the quantum setting with deterministic queries.  相似文献   

14.
量子计算机进入实验阶段   总被引:2,自引:1,他引:1  
首先简要介绍分层计算的制约;其次介绍最近量子信息的开发,在理论和实践两方面的通信和计算,诸如量子逻辑门、量子密码学、量子交缠性、超距传输的实验性实现、量子算法的首次实验性实现、量子因子分解、量子纪错码以及基于硅片的原子自旋量子计算机;最后讨论克服非相干性困难的方法。  相似文献   

15.
A long-standing aim of quantum information research is to understand what gives quantum computers their advantage. This requires separating problems that need genuinely quantum resources from those for which classical resources are enough. Two examples of quantum speed-up are the Deutsch–Jozsa and Simon’s problem, both efficiently solvable on a quantum Turing machine, and both believed to lack efficient classical solutions. Here we present a framework that can simulate both quantum algorithms efficiently, solving the Deutsch–Jozsa problem with probability 1 using only one oracle query, and Simon’s problem using linearly many oracle queries, just as expected of an ideal quantum computer. The presented simulation framework is in turn efficiently simulatable in a classical probabilistic Turing machine. This shows that the Deutsch–Jozsa and Simon’s problem do not require any genuinely quantum resources, and that the quantum algorithms show no speed-up when compared with their corresponding classical simulation. Finally, this gives insight into what properties are needed in the two algorithms and calls for further study of oracle separation between quantum and classical computation.  相似文献   

16.
该文以求解一些NP问题(如TSP问题和背包问题)为例,分析了运行在量子计算机上的量子搜索算法和运行在经典计算机上的进化搜索算法的本质区别,同时也论述了它们之间相互结合的方法,特别是运行在经典计算机上的量子驱动的进化算法。  相似文献   

17.
We discuss the simulation of complex dynamical systems on a quantum computer. We show that a quantum computer can be used to efficiently extract relevant physical information. It is possible to simulate the dynamical localization of classical chaos and extract the localization length with quadratic speed up with respect to any known classical computation. We can also compute with algebraic speed up the diffusion coefficient and the diffusion exponent, both in the regimes of Brownian and anomalous diffusion. Finally, we show that it is possible to extract the fidelity of the quantum motion, which measures the stability of the system under perturbations, with exponential speed up. The so-called quantum sawtooth map model is used as a test bench to illustrate these results. PACS: 03.67.Lx, 05.45.Mt  相似文献   

18.
在处理某些大规模并行问题时,量子计算因量子位独特的叠加态和纠缠态特性,相比经典计算机在并行处理方面具有更明显的优势。现阶段,物理量子比特计算机受限于可扩展性、相干时间和量子门操作精度,在经典计算机上开展量子计算模拟成为研究量子优越性和量子算法的有效途径。然而,随着量子比特数的增加,模拟所需的计算机资源呈指数增长。因此,研究大规模量子计算模拟在保证计算准确度、精度及效率的情况下减少模拟所需资源具有重要意义。从量子比特、量子门、量子线路、量子操作系统等方面展开,阐述量子计算的基本原理和背景知识。同时总结基于经典计算机的量子计算模拟基本方法,分析不同方法的设计思路和优缺点,列举目前常见的量子计算模拟器。在此基础上,针对量子计算模拟的通信开销问题,从节点拆分和通信优化2个方面出发,讨论基于超级计算机集群的量子计算模拟优化方法。  相似文献   

19.
Toward quantum computation: a five-qubit quantum processor   总被引:1,自引:0,他引:1  
Quantum physics presents intriguing possibilities for achieving computational gains after conventional miniaturization reaches its limits. Accordingly, we describe a nuclear magnetic-resonance quantum computer demonstrating a quantum algorithm that exponentially outperforms classical algorithms  相似文献   

20.
量子计算与量子计算机   总被引:4,自引:0,他引:4       下载免费PDF全文
量子计算是一种依照量子力学理论进行的新型计算,量子计算的基础和原理以及重要量子算法为在计算速度上超越图灵机模型提供了可能。在发展与完善量子计算理论的同时,量子计算机的物理实现方案也被不断提出。光子量子计算机,基于核磁共振、离子阱或谐振子等技术的量子计算机物理模型已被逐一实现。近年来亦出现了几个典型的基于量子计算机的量子算法。2001年在一台基于核磁共振技术的量子计算设备上成功演示的Shor量子算法,显示出量子计算机处理复杂问题的巨大潜能。文章对当前量子计算机物理实现的研究进展进行了综述。  相似文献   

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