We show how the techniques developed for long distance quantum key distribution in optical fibers can be used to demonstrate other quantuminformationprocessing and communication protocols. We present a fiber optics ...
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We show how the techniques developed for long distance quantum key distribution in optical fibers can be used to demonstrate other quantuminformationprocessing and communication protocols. We present a fiber optics realization of the Deutsch-Jozsa and Bernstein-Vazirani algorithms. We describe a method, called "error filtration", for reducing errors in quantum communication channels, and present an experimental implementation thereof. We discuss the cryptographic primitive of string flipping, and present an experimental implementation which has higher security than achievable using any classical protocol.
The paper is intended to be a survey of all the important aspects and results that have shaped the field of quantum computation and quantuminformation. The reader is first familiarized with those features and princip...
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The paper is intended to be a survey of all the important aspects and results that have shaped the field of quantum computation and quantuminformation. The reader is first familiarized with those features and principles of quantum mechanics providing a more efficient and secure informationprocessing. Their applications to the general theory of information, cryptography, algorithms, computational complexity and error-correction are then discussed. Prospects for building a practical quantum computer are also analyzed.
Quite often in database search, we only, need to extract portion of the information about the satisfying item. We consider this problem in the following form the database of N items is separated into K blocks of size ...
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Quite often in database search, we only, need to extract portion of the information about the satisfying item. We consider this problem in the following form the database of N items is separated into K blocks of size b = N/K elements each and an algorithm has just to find the block containing the item (of interest. The queries are exactly the same as in the standard database search problem. We present a quantum algorithm for this problem of partial search that takes about 0.34 root b fewer iterations than the quantum search algorithm.
The standard setting of quantum computation for continuous problems uses deterministic queries and the only source of randomness for quantumalgorithms is through measurement. Without loss of generality we may conside...
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The standard setting of quantum computation for continuous problems uses deterministic queries and the only source of randomness for quantumalgorithms is through measurement. Without loss of generality we may consider quantumalgorithms 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 8 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.
The Grover quantum algorithm can fired a target item in a database faster than any classical algorithm. In partial search, one trades accuracy for speed, and a part of the database (a block) containing the target item...
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The Grover quantum algorithm can fired a target item in a database faster than any classical algorithm. In partial search, one trades accuracy for speed, and a part of the database (a block) containing the target item can be found even faster. We consider different partial search algorithms and argue that the algorithm originally suggested by Grover and Radhakrishnan and modified by Korepin is the optimal one. The efficiency of an algorithm is measured by the number of queries to the oracle.
We use an annotated digital photo collection to demonstrate a two-level auto-layout technique consisting of a central primary region with secondary regions surrounding it. Because the object sizes within regions can o...
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We use an annotated digital photo collection to demonstrate a two-level auto-layout technique consisting of a central primary region with secondary regions surrounding it. Because the object sizes within regions can only be changed in discrete units, we refer to them as quantum content. Our real-time algorithms enable a compelling interactive display as users resize the canvas, or move and resize the primary region.
In number of Internet applications we need to search for objects to down load them. This includes peer-to-peer (P2P) file sharing, grid computing and content distribution networks. Here the single object will be searc...
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ISBN:
(纸本)0387446397
In number of Internet applications we need to search for objects to down load them. This includes peer-to-peer (P2P) file sharing, grid computing and content distribution networks. Here the single object will be searched for in multiple servers. There are many searching algorithms existing today for this purpose and uses the concept of classical physics and classical algorithms. The principles of quantum mechanics call be used to build and analyze a quantum computer and its algorithms. quantum searching is one such algorithm. In this paper we are proposing a search method based on quantum physics and quantumalgorithms.
We study a reduced quantum circuit computation paradigm in which the only allowable gates either permute the computational basis states or else apply a "global Hadamard operation", i.e. apply a Hadamard oper...
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We study a reduced quantum circuit computation paradigm in which the only allowable gates either permute the computational basis states or else apply a "global Hadamard operation", i.e. apply a Hadamard operation to every qubit simultaneously. In this model, we discuss complexity bounds (lower-bounding the number of global Hadamard operations) for common quantumalgorithms: we illustrate upper bounds for Shor's Algorithm, and prove lower bounds for Grover's Algorithm. We also use our formalism to display a gate that is neither quantum-universal nor classically simulable, on the assumption that Integer Factoring is not in BPP.
Optimal link adaption to the scattering function of wide sense stationary uncorrelated scattering (WSSUS) mobile communication channels is still an unsolved problem despite its importance for the next-generation syste...
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Optimal link adaption to the scattering function of wide sense stationary uncorrelated scattering (WSSUS) mobile communication channels is still an unsolved problem despite its importance for the next-generation system design. In a multicarrier transmission, such link adaption is performed by pulse shaping, i.e., by properly adjusting the transmit and receive filters. Pulse-shaped offset–quadratic-amplitude-modulation systems have been recently shown to have superior performance over standard cyclic prefix orthogonal frequency-division multiplexing (while operating at higher spectral efficiency). In this paper, we establish a general mathematical framework for joint transmitter and receiver pulse-shape optimization for so-called Weyl–Heisenberg or Gabor signaling, with respect to the scattering function of the WSSUS channel. In our framework, the pulse shape optimization problem is translated to an optimization problem over trace class operators, which in turn is related to fidelity optimization in quantuminformationprocessing. By convexity relaxation, the problem is shown to be equivalent to a convex constraint quasi-convex maximization problem, thereby revealing the nonconvex nature of the overall WSSUS pulse design problem. We present several iterative algorithms for optimization, providing applicable results even for large-scale problem constellations. We show that with transmitter-side knowledge of the channel statistics, a gain of 3–6 dB in signal-to-interference-plus-noise ratio can be expected.
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