quantum adiabatic algorithm is a method of solving computational problems by evolving the ground state of a slowly varying Hamiltonian. The technique uses evolution of the ground state of a slowly varying Hamiltonian ...
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quantum adiabatic algorithm is a method of solving computational problems by evolving the ground state of a slowly varying Hamiltonian. The technique uses evolution of the ground state of a slowly varying Hamiltonian to reach the required output state. In some cases, such as the adiabatic versions of Grover's search algorithm and Deutsch-Jozsa algorithm, applying the global adiabatic evolution yields a complexity similar to their classical algoritlims. However, Using the local adiabatic evolution, the algorithms given by J. Roland and N.J. Cerf for Grover's search [J. Roland, N.J. Cerf, quantum search by local adiabatic evolution, Phys. Rev. A 65 (2002) 042308] and by Saurya Das, Randy Kobes, and Gabor Kunstatter for the Deutsch-Jozsa algorithm [S. Das, R. Kobes, G. Kunstatter, Adiabatic quantum computation and Deutsch's algorithm, Phys. Rev. A 65 (2002) 062301] yield a complexity of order root N (where N = 2(n) and n is the number of cubits). In this paper, we report the experimental implementation of these local adiabatic evolution algorithms on a 2-qubit quantuminformation processor, by Nuclear Magnetic Resonance. (c) 2005 Elsevier Inc. All rights reserved.
quantum complexity theory is a powerful tool that provides deep insights into quantuminformationprocessing (QIP) and aims to do that also for quantum Mechanics (QM), in general. This paper is a short review of the m...
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quantum complexity theory is a powerful tool that provides deep insights into quantuminformationprocessing (QIP) and aims to do that also for quantum Mechanics (QM), in general. This paper is a short review of the main and new motivations, goals, tools, results and challenges of quantum complexity, oriented mainly for pedestrians.
As problems in computer science become increasingly more computationally intense, researchers have begun to examine other methods of computation. One of the largest new models of computation is the quantum computer. B...
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ISBN:
(纸本)078039187X
As problems in computer science become increasingly more computationally intense, researchers have begun to examine other methods of computation. One of the largest new models of computation is the quantum computer. Based on the concepts of quantum mechanics, quantum computers process bits of quantuminformation, or qubits, using quantum gates. So far some impressive results have been obtained using quantum computers on current problems (e.g. search problems). Many quantumalgorithms make use of the Hadamard Gate, and a few use a more general form of that gate. In this paper we present a generalized quantum gate that can be shown to encapsulate the standard gates used in quantumalgorithms and quantuminformationprocessing: Pauli X, Y, and Z, Hadamard, T Phase Shift, S Phase Shift, and Identity. This generalized gate may also lead to new, interesting, and useful gates for quantum computation.
quantum complexity theory is a powerful tool that provides deep insights into quantuminformationprocessing (QIP) and aims to do that also for quantum Mechanics (QM), in general. This paper is a short review of the m...
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quantum complexity theory is a powerful tool that provides deep insights into quantuminformationprocessing (QIP) and aims to do that also for quantum Mechanics (QM), in general. This paper is a short review of the main and new motivations, goals, tools, results and challenges of quantum complexity, oriented mainly for pedestrians.
In quantuminformation and quantum computing, the carrier of information is some quantum system and information is encoded in its state. After processing the state in the quantum processor, the information has to be r...
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ISBN:
(纸本)0819458376
In quantuminformation and quantum computing, the carrier of information is some quantum system and information is encoded in its state. After processing the state in the quantum processor, the information has to be read out. Clearly, this task is equivalent to determining the final state of the system. We begin by briefly reviewing various possible state discrimination strategies that are optimal with respect to some reasonable criteria and report on recent advances in the unambiguous discrimination of mixed quantum states. This strategy has been successfully applied to devise a class of novel probabilistic quantumalgorithms and has been demonstrated experimentally, using a linear optical implementation via generalized interferometers. In the second part we present a scheme for communication via completely unknown quantum states. In this context we discuss programmable quantum state discriminators that are universal, i.e. perform optimally on average, independently of the actual states used for the communication scheme. We conclude with a discussion of possible experimental implementations of the proposed device.
Research in quantum computation is looking for the consequences of having information encoding, processing and communication exploit the laws of quantum physics, i.e. the laws of the ultimate knowledge that we have, t...
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ISBN:
(纸本)3540278842
Research in quantum computation is looking for the consequences of having information encoding, processing and communication exploit the laws of quantum physics, i.e. the laws of the ultimate knowledge that we have, today, of the foreign world of elementary particles, as described by quantum mechanics. After an introduction to the principles of quantuminformationprocessing and a brief survey of the major breakthroughs brought by the first ten years of research in this domain, this paper concentrates on a typically "computer science" way to reach a deeper understanding of what it means to compute with quantum resources, namely on the design of programming languages for quantumalgorithms and protocols, and on the questions raised by the semantics of such languages. Special attention is devoted to the process algebraic approach to such languages, through a presentation of QPAlg, the quantum Process Algebra which is being designed by the authors.
This paper proposes a novel immune clonal algorithm, called a quantum-inspired immune clonal algorithm (QICA), which is based on the concept and principles of quantum computing, such as a quantum bit and superposition...
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We study the approximation of the smallest eigenvalue of a Sturm-Liouville problem in the classical and quantum settings. We consider a univariate Sturm-Liouville eigenvalue problem with a nonnegative function q from ...
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We study the approximation of the smallest eigenvalue of a Sturm-Liouville problem in the classical and quantum settings. We consider a univariate Sturm-Liouville eigenvalue problem with a nonnegative function q from the class C-2 ([0, 1]) and study the minimal number n(epsilon) of function evaluations or queries that are necessary to compute an E-approximation of the smallest eigenvalue. We prove that n(epsilon) = Theta (epsilon(-1/2)) in the (deterministic) worst case setting, and n (epsilon) = Theta(epsilon(-2/5)) in the randomized setting. The quantum selling offers a polynomial speedup with bit queries and an exponential speedup with power queries. Bit queries are similar to the oracle calls used in Grover's algorithm appropriately extended to real valued functions. Power queries are used for a number of problems including phase estimation. They are obtained by considering the propagator of the discretized system at a number of different time moments. They allow us to use powers of the unitary matrix exp((1/2)iM), where M is an n x n matrix obtained from the standard discretization of the Sturm-Liouville differential operator. The quantum implementation of power queries by a number of elementary quantum gates that is polylog in n is an open issue. In particular we show how to compute an E-approximation with probability (3/4) using n(epsilon) = Theta(epsilon(-1/3)) bit queries. For power queries, we use the phase estimation algorithm as a basic tool and present the algorithm that solves the problem using n(epsilon)= Theta(log epsilon(-1)) power queries, log(2) epsilon(-1) quantum operations, and (3/2) log epsilon(-1) quantum bits. We also drove that the minimal number of qubits needed for this problem (regardless of the kind of queries used) is at least roughly (1/2)log epsilon(-1). The lower bound on the number of quantum queries is proven in Bessen (in preparation). We derive a formula that relates the Sturm-Liouville eigenvalue problem to a weighted integrati
This paper presents algorithms for generating targeted name lists for candidate out-of-vocabulary (OOV) words for applications in language processing, particularly speech recognition. Focusing on names, which are show...
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This paper presents algorithms for generating targeted name lists for candidate out-of-vocabulary (OOV) words for applications in language processing, particularly speech recognition. Focusing on names, which are shown to be the dominant class of OOVs in news broadcasts, the approach involves offline generation of a large name list and online pruning based on a phonetic distance. The resulting list can be used in a rescoring pass in automatic speech recognition. We also show that a simple variation of the approach can be used to generate alternate name spellings, which may be useful for query expansion in information retrieval. By using a wide variety of sources, including automatic name phrase tagging of temporally relevant news text, OOV coverage can be improved by nearly a factor of two with only a 10% increase in the word list size. For one source, coverage increased from 13% to 94%. Phonetic pruning can be used to reduce the list size by an order of magnitude with only a small loss in coverage. (C) 2004 Elsevier Ltd. All rights reserved.
Single Ca+ ions and crystals of Ca+ ions are confined in a linear Paul trap and are investigated for quantuminformationprocessing. We here report on recent experimental advancements towards a quantum computer with s...
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